Storage Stability of Conventional and High Internal Phase Emulsions Stabilized Solely by Chickpea Aquafaba

Graziele Grossi Bovi Karatay; Andrêssa Maria Medeiros Theóphilo Galvão; Miriam Dupas Hubinger

doi:10.3390/foods11111588

Storage Stability of Conventional and High Internal Phase Emulsions Stabilized Solely by Chickpea Aquafaba

Grossi Bovi Karatay, Graziele;Medeiros Theóphilo Galvão, Andrêssa Maria;Dupas Hubinger, Miriam 2022-05-28 00:00:00 foods Article Storage Stability of Conventional and High Internal Phase Emulsions Stabilized Solely by Chickpea Aquafaba Graziele Grossi Bovi Karatay * , Andrêssa Maria Medeiros Theóphilo Galvão and Miriam Dupas Hubinger Department of Food Engineering and Technology, School of Food Engineering, University of Campinas (UNICAMP), Monteiro Lobato Street, 80, Campinas 13083-862, Brazil; [email protected] (A.M.M.T.G.); [email protected] (M.D.H.) * Correspondence: [email protected] Abstract: Aquafaba is a liquid residue of cooked pulses, which is generally discarded as waste. However, it is rich in proteins and, thus, can be used as a plant-based emulsiﬁer to structure vegetable oil. This study investigates chickpea aquafaba (CA) as an agent to structure different oil phase volumes (F) of canola oil (CO). CO was structured in the form of conventional emulsions (EF65% and EF70%) and high internal phase emulsion (HIPE) (EF75%) by the one-pot homogenization method. Emulsions were evaluated for a period of 60 days at 25 C in terms of average droplet size (11.0–15.9 m), microscopy, rheological properties, and oil loss (<1.5%). All systems presented predominantly elastic behavior and high resistance to coalescence. EF75% was the most stable system throughout the 60 days of storage. This study developed an inexpensive and easy to prepare potential substitute for saturated and trans-fat in food products. Moreover, it showed a valuable utilization of an often-wasted by-product and its conversion into a food ingredient. Citation: Grossi Bovi Karatay, G.; Medeiros Theóphilo Galvão, A.M.; Keywords: pulses; emulsiﬁer; stabilizers; oil structuring; HIPE; aquafaba Dupas Hubinger, M. Storage Stability of Conventional and High Internal Phase Emulsions Stabilized Solely by Chickpea Aquafaba. Foods 2022, 11, 1. Introduction 1588. https://doi.org/10.3390/ Cooking pulse seeds in water, canning, as well as hummus production, yields an foods11111588 inexpensive, viscous, rich liquid called aquafaba [1,2]. Aquafaba is an eco-friendly by- Academic Editors: Arun K. Bhunia, product, rich in nutrients, with vast potential to be used as a food ingredient due to its Joana S. Amaral, Derek V. Byrne, emulsibility, foamability, gelation, and thickening properties [2]. Aquafaba’s properties are Theodoros Varzakas, Esther Sendra attributed to its composition consisting of protein, polysaccharide, polysaccharide-protein and Benu P. Adhikari complexes, coacervates, saponins, and phenolic compounds [1,3–5]. This composition comes from the components transferred from seed to water during cooking, as well as from Received: 5 May 2022 Accepted: 27 May 2022 the interactions between these components under high pressure and temperature [6–8]. Published: 28 May 2022 Moreover, this composition is greatly inﬂuenced by pulse cultivar and cooking and soaking conditions [6]. Publisher’s Note: MDPI stays neutral Using aquafaba as a food ingredient is a “win–win–win–win” situation as (i) it is with regard to jurisdictional claims in environmentally sustainable since it enables the utilization of a by-product that is generally published maps and institutional afﬁl- discarded by end consumers; (ii) it is nutrient rich; (iii) it is a cheaper source of protein when iations. compared to animal-based- and plant-based-protein concentrates, isolates, and hydrolysate; and (iv) it is suitable for vegan products, for which the market is expected to rapidly expand in the upcoming years. Additionally, the use of aquafaba is in line with the trend of green Copyright: © 2022 by the authors. and clean labeling, and it is promising for a broad acceptance from a consumer awareness Licensee MDPI, Basel, Switzerland. point of view. This article is an open access article The emulsifying activity, capacity, and stability of chickpea aquafaba (CA) has been distributed under the terms and reported in various studies [5,9,10]. He et al. [6] evaluated different chickpea cultivars to conditions of the Creative Commons assess its inﬂuence on the emulsiﬁcation properties of CA-based emulsions with an oil phase Attribution (CC BY) license (https:// volume (F) of 70%. The authors reported that the emulsion capacity and stability among creativecommons.org/licenses/by/ the ﬁve chickpea cultivars ranged from 1.10 to 1.30 m /g and 71.9 to 77.1%, respectively. 4.0/). Foods 2022, 11, 1588. https://doi.org/10.3390/foods11111588 https://www.mdpi.com/journal/foods Foods 2022, 11, 1588 2 of 15 Lagarfa et al. [11] evaluated the inﬂuence of pH (3.5, 5, and 6.5) and chickpea-to-water ratio (1:1.5 to 1:5.0) during cooking on the emulsifying capacity of CA-based emulsions (F = 60%). The authors reported values within the range of 3.9–72.3% for emulsion capacity and 0.0–76.3% for emulsion stability, whereas Huang et al. [12] reported a 46% emulsifying activity of CA-based emulsions (F = 50%). The results from these different studies show the important role pH, chickpea/water ratio, F, and cultivars play on the emulsifying properties of CA-based emulsions. Even though there have been reports on CA emulsifying properties, emulsion proper- ties have only been partly elucidated and there is no in-depth study evaluating the stability of CA-based structured oils produced with different oil phase volumes over longer periods of storage. It is well known that one of the most difﬁcult problems to solve in emulsiﬁ- cation technology is the creation of stable emulsion structures that can resist prolonged storage without breakdown through physical instability mechanisms, such as gravitational separation and droplet aggregation [13]. Therefore, it is necessary to study such systems for longer storage periods in terms of its physicochemical and rheological behaviors to adequately evaluate its potential as a fat replacer. Among the different emulsion types, high internal phase emulsions (HIPEs) have at- tracted considerable interest to be used in food applications due to their elevated fat/water content (minimal F of 74%) and adjustable viscoelasticity [13,14]. One important appli- cation of HIPEs is as an alternative to partially hydrogenated oils (PHOs), and, in turn, trans-fatty acids (TFAs) as hydrogenation leads to the production of TFAs [13]. Recently, protein-stabilized HIPEs have been developed using a simple one-pot homogenization method, in which mixtures of oil and aqueous protein solution are sheared for short times [14–16]. In this context, this study aims to evaluate the use of chickpea aquafaba (CA) from a Brazilian cultivar (BRS Aleppo) as a structuring agent to structure canola oil (CO) in the form of conventional emulsions and HIPE through the one-pot homogenization method and its storage stability for a period of 60 days at 25 C. 2. Materials and Methods 2.1. Materials A kabuli type chickpea cultivar (Cicer arietinum (L.), var. BRS Aleppo) was kindly donated by Embrapa Vegetables (Brasilia, Brazil). All the seeds were frozen until the analyses. Canola oil (CO) (purity 100%; Seara Alimentos S.A, Sao Paulo, Brazil) was bought in a local supermarket (Dalben, Campinas, Brazil). Nile red, ﬂuorescein isothiocyanate (FITC) and sodium azide were obtained from Sigma-Aldrich (St. Louis, MO, USA) and all other chemical reagents were of analytical grade. 2.2. Chickpea Aquafaba (CA) Production First, the chickpea seed was manually cleaned to remove broken seed, dust, and other foreign materials. Then, 400 g of seed was presoaked in distilled water at a chickpea:water ratio of 1:3 (w/w) for 16 h at 5 C. Subsequently, 400 g of presoaked seed was rinsed with distilled water and mixed with distilled water at a chickpea:water ratio of 1:2 and cooked in a pressure cooker (Instant Pot 7 in 1 multi-use programmable pressure cooker, IPDUO60 V2, 6 quart/liters) at 115–118 C (an autogenic pressure range of 70–80 kPa) for 30 min. These conditions were chosen based on a previously reported study that evaluated the optimum conditions for producing CA with the best emulsion quality [1]. Following cooking, the cooked chickpeas were kept in the cooking pot for 6 h. The CA was then drained using a strainer and separated from the cooked chickpeas, weighed, and stored frozen until use. 2.3. CA Proximate Composition The moisture content of the CA was measured in an infrared moisture analyzer (model MOC63u, Shimadzu, Japan) at 105 C, until constant weight was reached [17]. For the determination of protein, ash, ﬁber, and fat, lyophilized CA was used, and the results were Foods 2022, 11, 1588 3 of 15 then converted to a wet basis. The total protein content of freeze-dried CA was quantiﬁed according to the Kjeldahl method using 6.25 factor for the conversion of nitrogen to protein. For ash determination, the samples were placed in previously weighed porcelain crucibles. The samples were then carbonized over a Bunsen burner and placed in a mufﬂe furnace heated to 550 C and left at this temperature for 6 h, and then transferred to a desiccator containing silica gel. After reaching room temperature, the crucibles containing the samples were weighed to determine the ash content by mass difference according to AOAC Ofﬁcial Method 923.03. For crude ﬁber determination, a modiﬁed Weende procedure was used. In short, the samples were ﬁrst boiled in sulfuric acid (1.25%) for the extraction of sugar and starch (acid digestion). The samples were then ﬁltered and washed with water to remove acid residues and neutralize the pH. Subsequently, the samples were boiled with 1.25% sodium hydroxide to remove proteins, hemicellulose, and lignin (alkali digestion). The samples were again ﬁltered and washed with water to remove alkali residues and neutralize the pH. The samples and ﬁlter were then dried at 100 C and then at 550 C in a mufﬂe furnace. Crude ﬁber was then determined by mass difference (AOAC Ofﬁcial method 930.10). The extraction of the lipid fraction was performed in accordance with the methodology described by Bligh and Dyer [18]. The total carbohydrate content was calculated as the difference between 100 and the sum of the percentage of moisture, ash, lipid, and protein. All chemical analyses were performed in three replications. 2.4. Conventional Emulsions and HIPE Production Conventional emulsions and HIPE formulated with CO and CA containing a con- centration of 0.05% (w/w) of sodium azide (for the inhibition of growth of microorgan- isms) were prepared by a one-pot homogenization method using a rotor-stator device ® ® (Ultraturrax T18 basic, IKA -Werke GmbH & Co., KG, Staufen, Germany) operating at 15.500 rpm for 1 min. CO was structured in the form of simple emulsions, namely, EF65% (35%CA and 65%CO) and EF70% (30%CA and 70%CO), and high internal phase emulsion (HIPE), EF75% (25%CA and 75%CO). The emulsions and HIPE were produced in triplicate, stored at 25 C, and characterized on selected days until 60 days of storage were reached. 2.5. Conventional Emulsions and HIPE Characterization 2.5.1. Droplet Size The dimensions of the droplets were determined by static light scattering using Mastersizer 2000 (Malvern Instruments Limited, Worcestershire, UK). The samples were dispersed in water with a refraction index of 1.33 and a rotation velocity of 2100 rpm at room temperature (25 C). The equipment possesses a stand-alone computer that runs the Malvern software. The Malvern software controls the optical bench and dispersion units and analyzes the raw data from the optical bench to determine the size of the particles, which are presented in many different formats. In this study, the droplet size was reported in terms of size distribution, volume-weighted (D ) and surface-weighted (D ) diameters, [4,3] [3,2] and span, according to Equations (1)–(3), respectively: n d D = (1) [4,3] n d n d D = (2) [4,3] n d d d (90) (10) Span = (3) (50) where d is the droplet diameter, n the number of drops, and d , d , and d are the i (10) (50) (90) diameters at 10%, 50%, and 90% of cumulative volume. Foods 2022, 11, 1588 4 of 15 2.5.2. Optical and Confocal Laser Scanning Microscopy All the samples were imaged via optical and confocal laser scanning microscopy (CLSM) using an optical microscope (Carl Zeiss, Axio Scopo A1, Aalen, Germany) at room temperature (25 C). The images were examined in the software AxioVision Rel. 4.8 (Carl Zeis, Aalen, Germany). For ﬂuorescence analysis, the samples were stained with 10 L of Nile red (0.1 g/L in polyethylene glycol) and 10 L of FITC (0.02 g/mL in ethanol). The protein was dyed with FITC (green) and CO with Nile red. 2.5.3. Rheological Measurements The rheological measurements of the samples were determined on an AR 1500 ex (TA Instruments, New Castle, PA, USA) using a 2 stainless-steel cone and plate (40 mm diameter and 47 m gap). Apparent viscosity data as a function of shear rate were acquired by performing ﬂow curves with shear rate values ranging from 0 to 300 s , with three sequential ramps: up– down–up cycles, respectively, aiming at the elimination of thixotropy. Data from the third ﬂow curve were adjusted according to the power law model, according to Equation (4): = k g (4) where is the shear stress (Pa); k is the ﬂow consistency index (Pas ); g is the shear rate (1/s), and n is the ﬂow behavior index (dimensionless). All the measurements were performed in triplicate at 25 C on day 0 (fresh) and after 3, 7, 14, 30, 45, and 60 days of storage. The viscoelastic behavior of the emulsions and HIPE was investigated by small am- plitude oscillatory measurements. First, a stress sweep was performed by logarithmically increasing the stress from 0.01 to 100 Pa at a frequency of 1 Hz to identify the linear vis- coelastic region (LVR) of the samples. Further rheological parameters at the LVR, such as the storage (G ) and loss (G” ) modulus, the limiting value of oscillatory stress (OSL), LVR LVR the loss-tangent (tan ), and the ﬂow-point oscillatory stress (FPOS) and ﬂow-point G LVR (FPG) for all samples, were determined from the amplitude sweep measurements. Frequency sweeps of 0.01–10 Hz were subsequently performed at 25 C and a ﬁxed strain value of 0.1 Pa (within the LVR). Data from the frequency sweep were adjusted according to a power law model according to Equation (5): 0 0 n0 G = k w (5) 0 0 n where G (Pa) is the storage modulus, k (Pas ) is a constant, w (rad/s) is the oscillation 0 0 frequency, and n (dimensionless) is the slope in a log–log plot of G versus w. Both frequency and amplitude measurements were performed in triplicate at 25 C on day 0 (fresh) and after 3, 7, 14, 30, 45, and 60 days of storage. Temperature sweep tests were performed in the range of 10 to 80 C with a ﬁxed strain value within the LVR and frequency of 1 Hz. All the measurements were performed in duplicate on day 0 (fresh) and after 3, 7, 14, 30, 45, and 60 days of storage. 2.5.4. Conventional Emulsions and HIPE Stability The stability of the conventional emulsions and HIPE was quantiﬁed in terms of centrifugal oil loss. Approximately 1 g of sample was put into Eppendorfs, centrifuged at 8600 g for 30 min at 5 C. Following centrifugation, free oil was removed and the sample mass without free oil was recorded and determined according to Equation (6): m m Centrifugal oil loss (%) = 100 (6) where m is the initial mass of the sample and m is the ﬁnal mass of the sample without i f free oil. Foods 2022, 11, 1588 5 of 15 2.6. Statistical Analyses The experimental data were depicted as the means standard deviation and analyzed applying one factor analysis of variance (ANOVA) using Statistica 8.0 software (Stat Soft. Inc., Tulsa, OK, USA). Signiﬁcant differences (p < 0.05) between means were detected using the Tukey test. Graphs were obtained with Microsoft Excel Ofﬁce 2016. 3. Results and Discussion 3.1. CA Proximate Composition Chickpea hulls work as a membrane that control mass transfer during the soaking and cooking processes. When these hulls are damaged, the release of chickpea seed components (e.g., protein and carbohydrate) into the water is facilitated [6,19]. In turn, the components released from the chickpea seed into the cooking water affects the CA composition and, consequently, the functional properties of the resulting CA. Therefore, determining the proximate composition of CA is of high importance. The moisture composition of CA in this study was 94.38% 0.19 and is in accordance with other studies. Shim et al. [20] reported on the moisture content of 10 commercial canned chickpea products; the values were between 92.98% and 95.12%. He et al. [6] produced CA from 5 different cultivars under similar conditions to the present study, and the reported values were in the range of 92.4% to 94.2%. As for Raikos et al. [21], who reported on canned CA, the reported value was 94.97%. The protein content of CA in this study was 1.21% 0.04. Stantiall et al. [4] produced CA by soaking chickpea seed (CS) in a 1:3.3 weight ratio (CS:water) for 16 h and cooking in a 1:1.75 weight ratio (CS:water) for 90 min; they reported a protein content of 0.95%. In the studies of Mustafa et al. [22] and Raikos et al. [21], the protein content value reported was 1.5% and 1.3%, respectively. Bulh et al. [10], who reported on the CA composition declared by the producer (Salling Group, Brabrand, Denmark), reported a relatively high protein composition of 6.3%. As for the ash content, the determined value in this study was 0.49% 0.01, which agrees with the previously reported values in the literature, which were 0.4%, 0.5%, and 0.6% in [4,21,22], respectively. The ﬁber content of CA was reported in very few studies and was 0.69 0.03 and 4.04 0.09 in [21,23], respectively. In this study, the determined value was 0.51 0.16. The carbohydrate content in this study was 3.39 %. Mustafa et al. [22] reported a 4% CA composition for simple and complex carbohydrates; whereas, in [10], the composition of carbohydrates was considerably high (i.e., 15%). As for the fat content, in some studies, it was not detected or was below the detection limit [4,22]. However, in our study, fat content was detected and was 0.14 0.01, which is in accordance with [23], who reported a value of 0.13 0.03 and with [21], who reported a value of <0.1%. A study on boiled chickpeas [24] reported a signiﬁcant loss of small fractions of fats upon boiling. This fat loss could have undergone two processes: (i) leaching out into the cooking water, such as the case in the present study; or, (ii) the fat was degraded during processing [4]. On the other hand, in the study of [10], a high fat content of 2.2 % was reported. In summary, these differences in the proximate composition of CA are due to many factors, such as the chickpea cultivar and especially the processing conditions used to produce the aquafaba. These different compounds can be tailored to have unique functional properties according to the desired use of the AQ. In this study, this speciﬁc composition was evaluated for its ability to structure liquid oil. 3.2. Droplet Size and Confocal Laser Scanning Microscopy The droplet-size distribution for all formulations remained with a bimodal proﬁle during the 60 days of storage (Figure 1). As can be observed, there were many overlapping curves throughout storage, indicating that the emulsions resisted prolonged storage without breakdown through physical instability mechanisms. Foods 2022, 11, x FOR PEER REVIEW 6 of 15 properties according to the desired use of the AQ. In this study, this specific composition was evaluated for its ability to structure liquid oil. 3.2. Droplet Size and Confocal Laser Scanning Microscopy The droplet-size distribution for all formulations remained with a bimodal profile during the 60 days of storage (Figure 1). As can be observed, there were many overlapping Foods 2022, 11, 1588 6 of 15 curves throughout storage, indicating that the emulsions resisted prolonged storage with- out breakdown through physical instability mechanisms. Figure 1. Droplet-size distribution of (a) EΦ65%, (b) EΦ70%, and (c) EΦ75% during 60 days of stor- Figure 1. Droplet-size distribution of (a) EF65%, (b) EF70%, and (c) EF75% during 60 days of age at 25 °C. storage at 25 C. Table 1 shows the droplet size, expressed in terms of D [4,3] (based on the volume of a Table 1 shows the droplet size, expressed in terms of D (based on the volume of [4,3] asp spher heree) ) an and d DD [3,2] (b(based ased on on ththe e didiameter ameter of of a sa pspher here).e). ThThe e resru esults lts of t of hethe dro dr pl oplet et size size in tin he [3,2] the prepr seesent nt stustudy dy wewer re wi e twithin hin thethe ran ranges ges of 11. of 11.0–12.8 0–12.8 µm , m, 12.12.3–13.0 3–13.0 µm,m, and and 14.14.1–15.9 1–15.9 µm m (D (D [4,3]) an ) and d 6.5 6.5–7.0 –7.0 µm m; ; 5.5.7–6.0 7–6.0 µ m m, , an and d 5. 5.4–5.7 4–5.7 µm m ((D D [3,2])) fo for r E EΦ F75% 75%, , E EF Φ70% 70%,, and and E EF Φ65%, 65%, [4,3] [3,2] rr espectively espectively . .Although Althoughthe theaverage averagedr dr oplet opletsizes sizesshowed showeda a signiﬁcant significantdif diffe ferr ence ence( p (p< < 0.05) 0.05) as as per per the the T T ukey’s ukey’stest, test,the thevariation variation in in sizes sizes between between days days 0 0 and and 60 60 did did not not exceed exceed 1.8, 1.8, 0.7, and 1.8 m (D ) and 0.7, 0.3, and 0.3 m (D ) for EF75%, EF70%, and EF65%, 0.7, and 1.8 µm (D [4,3]) and 0.7, 0.3, and 0.3 µm (D [3,2]) for EΦ75%, EΦ70%, and EΦ65%, [4,3] [3,2] respectively, which can be considered quite low. respectively, which can be considered quite low. Table 1. Droplet mean diameter (D and D ) of the emulsions and HIPE during 60 days of Table 1. Droplet mean diameter (D [4,3] and D [3,2]) of the emulsions and HIPE during 60 days of [4,3] [3,2] storage at 25 °C. storage at 25 C. D [4,3] (µm) D [3,2] (µm) D (m) D (m) [4,3] [3,2] Day EΦ65% EΦ70% EΦ75% EΦ65% EΦ70% EΦ75% Day EF65% EF70% EF75% EF65% EF70% EF75% aA aB aC aA abB bC 0 14.1 ± 0.1 12.3 ± 0.3 11.0 ± 0.2 6.5 ± 0.1 5.9 ± 0.1 5.5 ± 0.0 aA aB aC aA abB bC 0 14.1 0.1 12.3 0.3 11.0 0.2 6.5 0.1 5.9 0.1 5.5 0.0 bcA abB abC bA bcB abC 3 15.3 ± 0.5 12.5 ± 0.2 11.4 ± 0.1 7.0 ± 0.2 6.0 ± 0.1 5.4 ± 0.0 bcA abB abC bA bcB abC 3 15.3 0.5 12.5 0.2 11.4 0.1 7.0 0.2 6.0 0.1 5.4 0.0 abA abB abC aA abB abC 7 14.4 ± 0.8 12.8 ± 0.6 11.4 ± 0.2 6.3 ± 0.4 5.9 ± 0.4 5.4 ± 0.1 abA abB abC aA abB abC 14.4 0.8 12.8 0.6 11.4 0.2 6.3 0.4 5.9 0.4 5.4 0.1 cA bB bC bA cB bC cA bB bC bA cB bC 30 15.9 ± 1.3 12.9 ± 0.6 11.5 ± 0.2 7.0 ± 0.2 6.2 ± 0.2 5.7 ± 0.1 30 15.9 1.3 12.9 0.6 11.5 0.2 7.0 0.2 6.2 0.2 5.7 0.1 acA aB aC abA abB abA ab abC B abC acA aB aC 45 45 14.6 ± 0.4 12.5 ± 0.4 11.5 ± 0.3 6.6 ± 0.2 5.7 ± 0.1 5.4 ± 0.0 14.6 0.4 12.5 0.4 11.5 0.3 6.6 0.2 5.7 0.1 5.4 0.0 abA bB cB bcA abB cC abA bB cB bcA abB cC 60 14.8 0.6 13.0 0.3 12.8 0.8 6.9 0.1 5.9 0.1 5.7 0.1 60 14.8 ± 0.6 13.0 ± 0.3 12.8 ± 0.8 6.9 ± 0.1 5.9 ± 0.1 5.7 ± 0.1 Mean Mean values value(mean s (mean value valu e standar ± stand dar derivat d deriion, vatio nn = , n 9) =for 9) the for same the saparameter me param and eter column and col with umndif wfer ith ent lower-case superscript are signiﬁcantly different based on Tukey’s test at p < 0.05. Mean values for the same different lower-case superscript are significantly different based on Tukey’s test at p < 0.05. Mean parameter and row with different upper-case superscript are signiﬁcantly different by the Tukey’s test at p < 0.05. values for the same parameter and row with different upper-case superscript are significantly dif- ferent by the Tukey’s test at p < 0.05. As compared to other studies that produced protein and protein-polysaccharide- based HIPEs using the one-pot homogenization method (under slightly different time and As compared to other studies that produced protein and protein-polysaccharide- speed operating conditions), the results of this study produced emulsions and HIPEs with based HIPEs using the one-pot homogenization method (under slightly different time and relatively smaller or comparable droplet sizes. For instance, Zuo et al. [16] produced HIPEs speed operating conditions), the results of this study produced emulsions and HIPEs with using sonicated quinoa protein isolate (QPI) and peanut oil (F = 80%) and reported D relatively smaller or comparable droplet sizes. For instance, Zuo et al. [16] produced [4,3] values within the range of 30–52 m for HIPEs fabricated by sonicated QPI at low pH HIPEs using sonicated quinoa protein isolate (QPI) and peanut oil (Φ = 80%) and reported (3 and 5) and of 14–24 m for those fabricated in neutral and alkaline conditions, which D [4,3] values within the range of 30–52 µm for HIPEs fabricated by sonicated QPI at low was the case for the present study in which the pH of aquafaba was quantiﬁed close to pH (3 and 5) and of 14–24 µm for those fabricated in neutral and alkaline conditions, neutral (6.38 0.01). In the study of Vélez-Erazo et al. [15], who produced sunﬂower oil (F = 74–96%) HIPEs with pea protein isolate and different polysaccharides (i.e., xanthan gum, carrageenan, gum Arabic, alginate, gellan gum, tara gum, locust bean gum, and pectin), D was in the range of 16.24–25.79 m (depending on the polysaccharide used). [4,3] These results show that, apart from being stable in terms of droplet size and distribution for 60 days of storage, emulsions and HIPEs produced in this study had considerably lower droplet sizes compared to other studies, which, in turn, can indicate higher stability during prolonged storage times. As for the Span values (measures of absolute width), all Foods 2022, 11, x FOR PEER REVIEW 7 of 15 which was the case for the present study in which the pH of aquafaba was quantified close to neutral (6.38 ± 0.01). In the study of Vélez-Erazo et al. [15], who produced sunflower oil (Φ = 74–96%) HIPEs with pea protein isolate and different polysaccharides (i.e., xanthan gum, carrageenan, gum Arabic, alginate, gellan gum, tara gum, locust bean gum, and pec- tin), D [4,3] was in the range of 16.24–25.79 µm (depending on the polysaccharide used). These results show that, apart from being stable in terms of droplet size and distribution for 60 days of storage, emulsions and HIPEs produced in this study had considerably lower droplet sizes compared to other studies, which, in turn, can indicate higher stability during prolonged storage times. As for the Span values (measures of absolute width), all formulations presented a value of 1.6 throughout all the storage days, except for EΦ65% at day 30 and EΦ75% at day 60, for which the span value was of 1.7. A main difference between conventional emulsions and HIPEs is that the latter is a concentrated version of conventional emulsions, and typically has an internal phase (oil Foods 2022, 11, 1588 7 of 15 or water) volume fraction exceeding 74%, which is the case for the EΦ75% formulation in this study. At such a high concentration of oil, the oil droplets are tightly packed together and may adopt non-spherical shapes [13]. Nonetheless, in this study, the oil droplets in EΦ75% were mainly spherically shaped and did not present considerable differences from formulations presented a value of 1.6 throughout all the storage days, except for EF65% at the conventional emulsions, EΦ65% and EΦ70%, which can be confirmed by confocal laser day 30 and EF75% at day 60, for which the span value was of 1.7. scanning microscopy (Figure 2). It can be observed that the oil droplets of EΦ65% in- A main difference between conventional emulsions and HIPEs is that the latter is a creased considerably throughout the 60 days of storage. This was not evident in the drop- concentrated version of conventional emulsions, and typically has an internal phase (oil let-size results (Table 1), but could be noted in the size distribution graph (Figure 1), in or water) volume fraction exceeding 74%, which is the case for the EF75% formulation in this whic study h the . fi At rssuch t peak a high (lowe concentration r droplet sizes of ) d oil, ecrthe ease oil d i dr n oplets terms ar of ere tightly lative packed volume together (%) and and the smay econadopt d peaknon-spherical (higher drople shapes t sizes) [13 inc ].re Nonetheless, ased at longein r sthis torag study e day , s the (i.e oil ., ddr ay oplets s 45 an in d EF75% were mainly spherically shaped and did not present considerable differences from 60). the conventional Moreover, it emulsions, is possible E F to65% obse and rve E frF o70%, m the which sampcan les s be tai conﬁrmed ned with F by ITconfocal C that thlaser e oil scanning microscopy (Figure 2). It can be observed that the oil droplets of EF65% increased droplets were surrounded and coated with protein contained in the chickpea aquafaba considerably throughout the 60 days of storage. This was not evident in the droplet-size (CA). It is likely that both the protein and the starch, as well as all other bioactive mole- results (Table 1), but could be noted in the size distribution graph (Figure 1), in which the cules, leached out from the chickpea seed into the cooking water during the cooking pro- ﬁrst peak (lower droplet sizes) decreased in terms of relative volume (%) and the second cess that were responsible for enabling emulsification and providing stability to the sys- peak (higher droplet sizes) increased at longer storage days (i.e., days 45 and 60). tem, thereby preventing coalescence. Figure 2. Optical and fluorescence microscopic images of EΦ65%, EΦ70%, and EΦ75% at days 0 and 60; of Figure 2. Optical and ﬂuorescence microscopic images of E , E , and E at days 0 and 60; F65% F70% F75% storage at 25 °C (bar scale: 20 µm). Protein was dyed with FITC (green) and CO with Nile red. of storage at 25 C (bar scale: 20 m). Protein was dyed with FITC (green) and CO with Nile red. It has been frequently reported that HIPEs with small particle sizes possess relatively Moreover, it is possible to observe from the samples stained with FITC that the oil high stability; therefore this parameter is suitable and has been used as an index to evalu- droplets were surrounded and coated with protein contained in the chickpea aquafaba ate HIPE stability [25]. By taking this into account, it can be assumed that, as EΦ75% (CA). It is likely that both the protein and the starch, as well as all other bioactive molecules, leached out from the chickpea seed into the cooking water during the cooking process were responsible for enabling emulsiﬁcation and providing stability to the system, thereby preventing coalescence. It has been frequently reported that HIPEs with small particle sizes possess relatively high stability; therefore this parameter is suitable and has been used as an index to evaluate HIPE stability [25]. By taking this into account, it can be assumed that, as EF75% presented the smallest droplet size (conﬁrmed by D , D and the optical micrographs), it can [4,3] [3,2] be considered as the most stable system, followed by EF70% and EF65% in terms of size parameters. However, to further investigate the stability of these emulsions and HIPE, a combination of other parameters should be investigated. 3.3. Rheological Properties 3.3.1. Steady-Shear Behavior The ﬂow curve parameters (shear stress and shear rate) were ﬁtted to the power law model, and these are presented in Table 2. Foods 2022, 11, x FOR PEER REVIEW 8 of 15 Foods 2022, 11, x FOR PEER REVIEW 8 of 15 presented the smallest droplet size (confirmed by D [4,3], D [3,2] and the optical micro- presented the smallest droplet size (confirmed by D [4,3], D [3,2] and the optical micro- graphs), it can be considered as the most stable system, followed by EΦ70% and EΦ65% graphs), it can be considered as the most stable system, followed by EΦ70% and EΦ65% in terms of size parameters. However, to further investigate the stability of these emul- in terms of size parameters. However, to further investigate the stability of these emul- sions and HIPE, a combination of other parameters should be investigated. sions and HIPE, a combination of other parameters should be investigated. 3.3. Rheological Properties 3.3. Rheological Properties 3.3.1. Steady-Shear Behavior 3.3.1. Steady-Shear Behavior The flow curve parameters (shear stress and shear rate) were fitted to the power law The flow curve parameters (shear stress and shear rate) were fitted to the power law model, and these are presented in Table 2. model, and these are presented in Table 2. With respect to the variation in the modeled parameters (i.e., k and n) within the 60 With respect to the variation in the modeled parameters (i.e., k and n) within the 60 days of storage, there were significant differences (p < 0.05) among all the samples. The days of storage, there were significant differences (p < 0.05) among all the samples. The flow behavior index (n) values, which indicate the degree of non-Newtonian characteris- flow behavior index (n) values, which indicate the degree of non-Newtonian characteris- tics of the fluid, were between 0.31 and 0.50 (n < 1) for all the samples throughout storage, tics of the fluid, were between 0.31 and 0.50 (n < 1) for all the samples throughout storage, corresponding to a pseudoplastic behavior. At a higher oil concentration, the n values corresponding to a pseudoplastic behavior. At a higher oil concentration, the n values were lower, suggesting that the HIPE (EΦ75%) formed a more structured gel. The flow were lower, suggesting that the HIPE (EΦ75%) formed a more structured gel. The flow consistency index (k) is related to the apparent viscosity of the samples; the more viscous consistency index (k) is related to the apparent viscosity of the samples; the more viscous the sample, the higher the k. From our results, the k values were higher in the samples the sample, the higher the k. From our results, the k values were higher in the samples that contained more oil, which means that the HIPE (EΦ75%) was more structured and that contained more oil, which means that the HIPE (EΦ75%) was more structured and Foods 2022, 11, 1588 8 of 15 firmer than the emulsions (EΦ70% and EΦ65%), which can be confirmed by the apparent firmer than the emulsions (EΦ70% and EΦ65%), which can be confirmed by the apparent viscosity results at the shear rates of 5 and 300 per second (Table 2). These results can be viscosity results at the shear rates of 5 and 300 per second (Table 2). These results can be related to the droplet size of the samples, as the bigger the droplet size, the lower the related to the droplet size of the samples, as the bigger the droplet size, the lower the surface area available for droplets to interact, which, in turn, leads to lower shear thinning su Tr able face a 2. reFlow a avaiconsistency lable for drop index lets to(k) intand eractﬂow , whic behavior h, in turnindex , leads (tn o) lof owthe er sh power ear thilaw nninmodel g (R > 0.99), behavior and, consequently, lower viscosity [26,27]. behavior and, consequently, lower viscosity [26,27]. and apparent viscosity () at a shear rate of 5 ( ) and 300 s ( ) and the initial shear stress ( ) 5 300 0 Tab thr leoughout 2. Flow cothe nsist 60 enc days y inde of x (storage k) and float w 25 behaC. vior index (n) of the power law model (R >0.99), Table 2. Flow consistency index (k) and flow behavior index (n) of the power law model (R >0.99), −1 and apparent viscosity (η) at a shear rate of 5 (η5) and 300 s (η300) and the initial shear stress (σ0) −1 and apparent viscosity (η) at a shear rate of 5 (η5) and 300 s (η300) and the initial shear stress (σ0) throughout the 60 days of storage at 25 °C. Model Parameters (=kg ) Experimental Parameters throughout the 60 days of storage at 25 °C. Model Parame nters (σ = k * ) Experimental Parameters Storage (d) k (Pas ) n (Pas) (Pas) (Pa) 5 300 0 Model Parameters (σ = k * ) Experimental Parameters Storage (d) k (Pa.s ) n η5 (Pa.s) η300 (Pa.s) σ0 (Pa) Storage (d) k (Pa.s ) n η5 (Pa.s) η300 (Pa.s) σ0 (Pa) EF65% EΦ65% EΦ65% ab abc ab a a ab abc ab a a 0 0 4.75 4.75 ± 0.15 0.15 0.48 ± 0. 0.48 01 0.011.83 ± 0.03 1.83 0. 0.03 25 ± 0.00 0.256. 540.00 ± 0.26 6.54 0.26 ab abc ab a a 0 4.75 ± 0.15 0.48 ± 0.01 1.83 ± 0.03 0.25 ± 0.00 6.54 ± 0.26 a c ab ab a a c ab ab a 3 5.81 0.21 0.47 0.00 8.47 0.68 3 5.81 ± 0.21 0.47 ± 0.00 2.27 ± 0.15 2.27 0. 0.15 28 ± 0.01 0.288. 47 0.01 ± 0.68 a c ab ab a 3 5.81 ± 0.21 0.47 ± 0.00 2.27 ± 0.15 0.28 ± 0.01 8.47 ± 0.68 a ac b b a a ac b b a 7 5.84 0.52 0.47 0.01 2.34 0.27 0.29 0.02 8.50 0.96 7 5.84 ± 0.52 0.47 ± 0.01 2.34 ± 0.27 0.29 ± 0.02 8.50 ± 0.96 a ac b b a 7 5.84 ± 0.52 0.47 ± 0.01 2.34 ± 0.27 0.29 ± 0.02 8.50 ± 0.96 a ab abc ab a b ab abc ab a b a 14 5.19 0.62 0.48 0.01 2.14 0.25 0.27 0.01 7.86 0.92 14 5.19 ± 0.62 0.48 ± 0.01 2.14 ± 0.25 0.27 ± 0.01 7.86 ± 0.92 ab abc ab a b a 14 5.19 ± 0.62 ab 0.48 ± 0.01 2. ab 14 ± 0.25 0.27 ± b 0.01 7.86 ± 0. ab 92 a ab ab b ab a 30 4.75 0.60 0.49 0.01 1.94 0.22 0.26 0.01 7.03 1.15 30 4.75 ± 0.60 0.49 ± 0.01 1.94 ± 0.22 0.26 ± 0.01 7.03 ± 1.15 ab ab b ab a 30 4.75 ± 0.60 0.49 ± 0.01 1.94 ± 0.22 0.26 ± 0.01 7.03 ± 1.15 a ab ab ab ab ab ab ab ab a 45 4.80 0.24 0.49 0.00 1.95 0.15 0.27 0.01 7.17 0.73 45 4.80 ± 0.24 0.49 ± 0.00 1.95 ± 0.15 0.27 ± 0.01 7.17 ± 0.73 ab ab ab ab a 45 4.80 ± 0.24 b 0.49 ± 0.00 1. b95 ± 0.15 0.27 ± a 0.01 7.17 ± 0. ab 73 a 60 b b 1.80 a 0.06 ab a 6.41 0.28 4.40 0.04 0.50 0.00 0.26 0.00 60 4.40 ± 0.04 0.50 ± 0.00 1.80 ± 0.06 0.26 ± 0.00 6.41 ± 0.28 b b a ab a 60 4.40 ± 0.04 0.50 ± 0.00 1.80 ± 0.06 0.26 ± 0.00 6.41 ± 0.28 EΦ70% EF70% EΦ70% a ab a a a 0 10.86 ± 0.65 0.41 ± 0.00 4.02 ± 0.24 0.37 ± 0.02 16.47 ± 1.17 a ab a a a a ab a a a 0 10.86 0.65 4.02 0.24 0.37 0.02 16.47 1.17 0 10.86 ± 0.65 0.41 ± 0.41 0.00 0.00 4.02 ± 0.24 0.37 ± 0.02 16.47 ± 1.17 cd ac a b bc 3 13.12 ± 0.26 0.40 ± 0.00 4.82 ± 0.36 0.43 ± 0.02 20.25 ± 1.04 cd ac a b bc cd ac a b bc 3 13.12 0.26 0.40 0.00 4.82 0.36 0.43 0.02 20.25 1.04 3 13.12 ± 0.26 0.40 ± 0.00 4.82 ± 0.36 0.43 ± 0.02 20.25 ± 1.04 d c a b c 7 13.49 ± 0.44 0.39 ± 0.00 4.83 ± 0.43 0.43 ± 0.02 20.44 ± 1.00 c a c d b d c a b c 7 13.49 0.44 0.39 0.00 4.83 0.43 0.43 0.02 20.44 1.00 7 13.49 ± 0.44 0.39 ± 0.00 4.83 ± 0.43 0.43 ± 0.02 20.44 ± 1.00 abcd abc a ab abc 14 11.95 ± 0.66 0.40 ± 0.00 4.47 ± 0.39 0.40 ± 0.01 18.55 ± 1.58 abcd abc a ab abc 14 abcd abc 4.47 a 0.39 ab abc 11.95 0.66 0.40 0.00 0.40 0.01 18.55 1.58 14 11.95 ± 0.66 0.40 ± 0.00 4.47 ± 0.39 0.40 ± 0.01 18.55 ± 1.58 ab b a ab ab 30 10.94 ± 0.71 0.41 ± 0.00 4.13 ± 0.31 0.39 ± 0.02 16.65 ± 1.47 ab b a ab ab 30 10.94 a0.71 b 0.41 b 0.00 4.13 a 0.31 ab0.39 0.02 ab 16.65 1.47 30 10.94 ± 0.71 0.41 ± 0.00 4.13 ± 0.31 0.39 ± 0.02 16.65 ± 1.47 bcd abc a b abc 45 12.63 ± 1.00 0.41 ± 0.00 4.62 ± 0.49 0.43 ± 0.02 18.59 ± 2.06 bcd abc a b abc 45 4.62 0.49 12.63 b1.00 cd 0.41 abc0.00 a b 0.43 0.02 abc 18.59 2.06 Foods 2022, 11, x FOR 45 PE ER REVIEW 12. 63 ± 1.00 0.41 ± 0.00 4.62 ± 0.49 0.43 ± 0.02 18.59 ± 2.06 9 of 15 abc ab a ab ab 60 11.74 ± 0.24 0.41 ± 0.01 4.16 ± 0.21 0.41 ± 0.01 16.67 ± 0.48 abc ab a ab ab 60 11.74 a0.24 bc 0.41 ab 0.01 4.16 a 0.21 ab0.41 0.01 ab 16.67 0.48 60 11.74 ± 0.24 0.41 ± 0.01 4.16 ± 0.21 0.41 ± 0.01 16.67 ± 0.48 EΦ75% EΦ75% a abc a a a EF75% 0 26.69 ± 2.93 0.32 ± 0.01 8.96 ± 0.86 0.55 ± 0.06 40.67 ± 4.33 a abc a a a 0 26.69 ± 2.93 0.32 ± 0.01 8.96 ± 0.86 0.55 ± 0.06 40.67 ± 4.33 ab a a ab ab 3 33.93 ± 3.09 a 0.31 ± 0.00 11. abc 31 ± 1.30 0.65 ± a0.07 50.55 ± 5.73 a a 0 26.69 2.93 ab 0.32 0.01 bc 8.96 0.86 a 0.55 0.06 ab 40.67 4.33 ab 45 31.02 ± 1.92 0.32 ± 0.00 10.37 ± 0.61 0.66 ± 0.02 44.55 ± 2.67 ab a a ab ab 3 33.93 ± 3.09 0.31 ± 0.00 11.31 ± 1.30 0.65 ± 0.07 50.55 ± 5.73 ab abc a ab ab a a 7 31.28 ± 3.19 ab 0.31 ± 0.01 10.07 ± 1.20 0.63 ± 0.03 46.28 ± 4.ab 77 ab 3 33.93 3.09 0.31 0.00 11.31 1.30 0.65 0.07 50.55 5.73 ab abc a ab ab 7 31.28 ± 3.19 0.31 ± 0.01 10.07 ± 1.20 0.63 ± 0.03 46.28 ± 4.77 b ab a b b ab abc a ab ab 14 35.74 ± 3.98 0.31 ± 0.01 11.27 ± 1.22 0.69 ± 0.04 53.37 ± 5.72 7 10.07 1.20 31.28 3.19 0.31 0.01 0.63 0.03 46.28 4.77 b ab a b b 14 35.74 ± 3.98 0.31 ± 0.01 11.27 ± 1.22 0.69 ± 0.04 53.37 ± 5.72 ab abc a ab ab b ab a b b 30 28.54 ± 1.10 0.32 ± 0.01 9.42 ± 0.23 0.61 ± 0.04 42.90 ± 1.20 14 35.74 3.98 0.31 0.01 11.27 1.22 0.69 0.04 53.37 5.72 ab abc a ab ab 30 28.54 ± 1.10 ab0.32 ± 0.01 9.42 c ± 0.23 0.61 ± 0.0 a4 42.90 ± 1.20 ab ab 60 30.45 ± 1.41 ab 0.33 ± 0. abc 01 9.88 ± 0.51 0.66 ± 0.0 ab 1 42.45 ± 2.22 ab 30 9.42 0.23 28.54 1.10 0.32 0.01 0.61 0.04 42.90 1.20 ab bc a ab ab 45 31.02 1.92 0.32 0.00 10.37 0.61 0.66 0.02 44.55 2.67 c a ab ab ab 60 30.45 1.41 0.33 0.01 9.88 0.51 0.66 0.01 42.45 2.22 n n is σ shear is she str ar ess stre (Pa); ss (P kais ); k ﬂow is fl consistency ow consistindex ency i(Pa ndes) x (;P a·is s)shear ; γ is rate shear (1/s); rateand (1/sn ); is an ﬂow d n ibehavior s flow be inde havxior (dimensionless). Mean values (mean value standard derivation, n = 3) for the same parameter, sample, and index (dimensionless). Mean values (mean value ± standard derivation, n = 3) for the same param- column with different lower-case superscripts are signiﬁcantly different based on Tukey’s test at p < 0.05. eter, sample, and column with different lower-case superscripts are significantly different based on Tukey’s test at p < 0.05. With respect to the variation in the modeled parameters (i.e., k and n) within the 60 days of storage, there were signiﬁcant differences (p < 0.05) among all the samples. The Viscosity is an important parameter to evaluate, as it describes the flow properties of ﬂow behavior index (n) values, which indicate the degree of non-Newtonian characteristics a system and can directly affect the appearance and the consistency of a product. It is of the ﬂuid, were between 0.31 and 0.50 (n < 1) for all the samples throughout storage, directly dependent on strain rate; therefore, it is determined in terms of apparent viscosity corresponding to a pseudoplastic behavior. At a higher oil −1 concentration, −1 the n values and was expressed in this study at the shear rates of 300 s and 5 s (Table 2). Both emul- were lower, suggesting that the HIPE (EF75%) formed a more structured gel. The ﬂow sions and the HIPE showed shear-thinning behavior, which is characteristic of non-New- consistency index (k) is related to the apparent viscosity of the samples; the more viscous tonian fluids whose viscosity decreases under increasing shear rates. Moreover, at higher the sample, the higher the k. From our results, the k values were higher in the samples that oil concentrations (EΦ75% > EΦ70% > EΦ65%) the shear stress was higher, resulting in contained more oil, which means that the HIPE (EF75%) was more structured and ﬁrmer increased viscosity, a parameter that can be a valuable feature depending on the desired than the emulsions (EF70% and EF65%), which can be conﬁrmed by the apparent viscosity application. With respect to the variation in the apparent viscosity both at the shear rates results at − the 1 shear −1rates of 5 and 300 per second (Table 2). These results can be related to of 300 s and 5 s within the 60 days of storage, there was a significant difference (p < 0.05) the droplet size of the samples, as the bigger the droplet size, the lower the surface area −1 for all samples except for EΦ75% (at a shear rate of 5 s ). available for droplets to interact, which, in turn, leads to lower shear thinning behavior All the samples presented an initial shear stress (σ0) throughout storage (Table 2). and, consequently, lower viscosity [26,27]. With respect to the variation in the initial shear stress within 60 days of storage, there was Viscosity is an important parameter to evaluate, as it describes the ﬂow properties a significant difference (p < 0.05) for all samples except for EΦ65%. The presence of σ0 of a system and can directly affect the appearance and the consistency of a product. It is indicates that the system needs an initial force to be applied for the sample to begin flow- directly dependent on strain rate; therefore, it is determined in terms of apparent viscosity ing. In turn, σ0 values are directly related to sample fluidity. Fluidity is defined as the 1 1 and was expressed in this study at the shear rates of 300 s and 5 s (Table 2). Both ability of the sample to retain its appearance and structural integrity when inverted. In emulsions and the HIPE showed shear-thinning behavior, which is characteristic of non- that sense, the higher the σ0, the higher the ability of the system to retain its appearance, Newtonian ﬂuids whose viscosity decreases under increasing shear rates. Moreover, at which was confirmed by photographs taken directly after the samples were inverted (Ta- ble 2). As can be observed, both EΦ70% and EΦ75% presented higher σ0 and consequently lower mobility, when compared to EΦ65% at day 0 (Figure 3a) as well as throughout all the storage days. Higher fluidity indicates that molecules are less viscous and packed to- gether to a lesser extent, which can be confirmed by the apparent viscosity results (Table 2) and the optical and fluorescence microscopic images (Figure 2). In summary, as EΦ75% is more viscous, and presented higher k values and lower n values, it can be considered as the most stable system, followed by EΦ70% and EΦ65%. Figure 3. Flow curves plotted as shear stress versus shear rate (a), stress sweeps (b), and frequency (c) tests of EΦ65%, EΦ70%, and EΦ75% at day 0 of storage at 25 °C. 3.3.2. Oscillatory Shear Behavior Amplitude Sweep Foods 2022, 11, x FOR PEER REVIEW 9 of 15 ab bc a ab ab 45 31.02 ± 1.92 0.32 ± 0.00 10.37 ± 0.61 0.66 ± 0.02 44.55 ± 2.67 ab c a ab ab 60 30.45 ± 1.41 0.33 ± 0.01 9.88 ± 0.51 0.66 ± 0.01 42.45 ± 2.22 σ is shear stress (Pa); k is flow consistency index (Pa·s) ; γ is shear rate (1/s); and n is flow behavior index (dimensionless). Mean values (mean value ± standard derivation, n = 3) for the same param- eter, sample, and column with different lower-case superscripts are significantly different based on Tukey’s test at p < 0.05. Viscosity is an important parameter to evaluate, as it describes the flow properties of a system and can directly affect the appearance and the consistency of a product. It is directly dependent on strain rate; therefore, it is determined in terms of apparent viscosity −1 −1 and was expressed in this study at the shear rates of 300 s and 5 s (Table 2). Both emul- Foods 2022, 11, 1588 9 of 15 sions and the HIPE showed shear-thinning behavior, which is characteristic of non-New- tonian fluids whose viscosity decreases under increasing shear rates. Moreover, at higher oil concentrations (EΦ75% > EΦ70% > EΦ65%) the shear stress was higher, resulting in higher oil concentrations (EF75% > EF70% > EF65%) the shear stress was higher, resulting increased viscosity, a parameter that can be a valuable feature depending on the desired in increased viscosity, a parameter that can be a valuable feature depending on the desired application. With respect to the variation in the apparent viscosity both at the shear rates application. With respect to the variation in the apparent viscosity both at the shear rates of −1 −1 1 1 of 300 s and 5 s within the 60 days of storage, there was a significant difference (p < 0.05) 300 s and 5 s within the 60 days of storage, there was a signiﬁcant difference (p < 0.05) −1 for all samples except for EΦ75% (at a shear rate of 5 s ). for all samples except for EF75% (at a shear rate of 5 s ). All the samples presented an initial shear stress (σ0) throughout storage (Table 2). All the samples presented an initial shear stress ( ) throughout storage (Table 2). With respect to the variation in the initial shear stress within 60 days of storage, there was With respect to the variation in the initial shear stress within 60 days of storage, there was a significant difference (p < 0.05) for all samples except for EΦ65%. The presence of σ0 a signiﬁcant difference (p < 0.05) for all samples except for EF65%. The presence of indicates that the system needs an initial force to be applied for the sample to begin flow- indicates that the system needs an initial force to be applied for the sample to begin ﬂowing. ing. In turn, σ0 values are directly related to sample fluidity. Fluidity is defined as the In turn, values are directly related to sample ﬂuidity. Fluidity is deﬁned as the ability of ability of the sample to retain its appearance and structural integrity when inverted. In the sample to retain its appearance and structural integrity when inverted. In that sense, that sense, the higher the σ0, the higher the ability of the system to retain its appearance, the higher the , the higher the ability of the system to retain its appearance, which was wh conﬁrmed ich was c by onphotographs firmed by pho taken tograp dir hsectly taken after direthe ctly samples after the wer samepinverted les were i(T nv able erted 2). (TAs a- ble 2). As can be observed, both EΦ70% and EΦ75% presented higher σ0 and consequently can be observed, both EF70% and EF75% presented higher and consequently lower lmobility ower mo , b when ility, wh compar en coed mpto are E dF t65% o EΦat 65% day at 0 day (Figur 0 (Fe ig3 u a) re as 3a) well as we asllthr asoughout througho all ut the all tstorage he storag days. e day Higher s. High ﬂu eridity fluid indicates ity indica that tes tmolecules hat molecu ar le esless are viscous less viscand ous packed and pac tk ogether ed to- to a lesser extent, which can be conﬁrmed by the apparent viscosity results (Table 2) and gether to a lesser extent, which can be confirmed by the apparent viscosity results (Table the optical and ﬂuorescence microscopic images (Figure 2). In summary, as EF75% is more 2) and the optical and fluorescence microscopic images (Figure 2). In summary, as EΦ75% viscous, and presented higher k values and lower n values, it can be considered as the most is more viscous, and presented higher k values and lower n values, it can be considered stable system, followed by EF70% and EF65%. as the most stable system, followed by EΦ70% and EΦ65%. Figure 3. Flow curves plotted as shear stress versus shear rate (a), stress sweeps (b), and frequency Figure 3. Flow curves plotted as shear stress versus shear rate (a), stress sweeps (b), and frequency ((c c)) ttests ests o of f E EΦF6 65%, 5%, E EΦF 70 70%, %, an and d E E ΦF 775% 5% atat day day 0 0 ofof ststorage orage atat 25 25 °CC. . 3.3.2. Oscillatory Shear Behavior 3.3.2. Oscillatory Shear Behavior Amplitude Sweep Amplitude Sweep An amplitude sweep test was conducted by varying the oscillatory stress (0.01–100 Pa) at a ﬁxed frequency (1 Hz). This determined the linear viscoelastic region (LVR), in which G (storage modulus) and G” (viscous modulus) were almost constant, and the nonlinear region, in which G and G” started to decrease [28]. The oscillatory stress value, at which G sharply decreased, is deﬁned as the critical oscillatory stress, also known as the limiting value of oscillatory stress (OS ). On day 0 (Figure 3b), at low-stress values (0.01–1 Pa), the G value of EF75% was the highest (~1250 Pa), showing higher elastic behavior when compared to EF70% and EF65%, which presented G of ~700 Pa and 380 Pa, respectively. When the stress was increased (>1 Pa), it was possible to identify the OS values, which were 1, 5, and 20 for EF65%, EF70%, and EF75%, respectively. Determining the OS value is important as it determines the maximum deformation that a system can withstand without structural breakdown [28]. Results of this study show that EF65% (lower OS ) is the ﬁrst to lose structure, followed by EF70% and EF75%. This outcome indicates that an increase in the oil concentration improves the strength and rigidity of the system. To evaluate if the samples maintained their initial structure throughout the 60 days of storage, further rheological parameters at the LVR were determined from the amplitude sweep measurements (Table 3). Foods 2022, 11, 1588 10 of 15 Table 3. Rheological parameters of storage (G ) and loss (G” ) moduli at the linear viscoelastic LVR LVR region (LVR), limiting value of oscillatory stress (OS ), the loss-tangent (tan ) at the LVR, ﬂow- L LVR point oscillatory stress (FP ), and ﬂow-point G (FP ) as determined by stress sweep tests (at a 1 Hz OS G frequency) for samples stored at 25 C. Sample Storage (d) G” (Pa) OS (Pa) tan FP (Pa) FP (Pa) G (Pa) LVR LVR L LVR OS G ac a a a ab cd 0 380.94 37.04 1.26 0.00 0.15 0.00 105.27 34.63 58.70 5.42 2.64 0.34 a a a e a bc 3 426.55 43.31 1.26 0.00 0.17 0.02 4.03 0.65 74.56 21.71 72.01 7.90 a bc a a d a 452.70 8.89 72.63 1.66 1.26 0.00 0.16 0.00 2.84 0.00 107.11 28.33 ac c e a ab bcd EF65% 14 415.05 50.79 81.13 7.37 1.00 0.00 115.47 26.41 0.20 0.02 2.45 0.34 bc ab d ab ab 30 79.37 35.80 318.57 47.74 59.10 10.2 0.74 0.09 0.19 0.02 1.61 0.26 b a c b a a 45 53.62 1.02 0.63 0.00 1.32 0.17 81.25 8.28 243.02 34.13 0.22 0.03 a a b b b abc 60 47.46 5.58 58.21 5.13 215.58 30.05 0.50 0.00 0.22 0.01 1.79 0.00 a b e a bc ab 0 695.53 39.37 5.01 0.00 0.11 0.00 76.11 3.66 10.52 1.34 181.60 17.44 a e c a ab ab 3 742.63 27.58 5.01 0.00 12.27 1.69 147.08 7.24 84.90 2.52 0.11 0.00 a a d bc abc ab 7 753.74 50.41 97.10 12.31 3.98 0.00 0.13 0.01 8.36 1.07 203.23 12.49 a a cd cd ab b EF70% 14 764.28 42.70 99.46 4.70 3.71 0.47 0.13 0.00 6.56 2.74 227.96 34.67 ab bc abc ab b 30 749.47 26.23 91.81 3.21 3.16 0.00 0.12 0.00 7.13 0.00 241.78 43.84 a a ab d a ab 45 661.30 38.73 95.45 5.11 5.49 0.92 2.73 0.38 0.14 0.00 205.81 29.12 a e a a b ab 60 2.03 0.46 0.17 0.01 5.27 0.67 144.58 13.76 532.30 38.38 89.48 4.75 c a d a b a 0 1377.74 69.46 120.09 25.22 0.10 0.01 318.96 39.47 19.95 0.00 65.56 27.44 a a c a ab ab 3 1142.70 21.02 114.06 2.20 15.85 0.00 0.10 0.00 41.88 5.34 241.61 44.11 a a a a b ab 7 1087.21 27.81 103.38 6.76 12.59 0.00 0.09 0.01 34.35 2.36 257.43 17.40 a a a b ab ab EF75% 14 1190.30 71.31 117.95 10.63 0.10 0.00 12.59 0.00 35.72 0.00 279.65 54.68 a a a a ab b 30 1073.52 37.48 101.29 4.07 7.94 0.00 0.09 0.00 41.88 5.34 170.20 13.41 a a a a a a 45 1157.35 68.12 114.39 1.69 7.94 0.00 0.10 0.00 25.45 2.92 293.23 61.55 a a a a b ab 60 928.37 41.38 105.39 6.47 7.40 0.94 0.11 0.01 20.99 2.68 247.10 44.41 Flow point (G = G”). Mean values (mean value standard derivation, n = 3) for the same parameter, sample, and column with different lower-case superscripts are signiﬁcantly different based on Tukey’s test at p < 0.05. The results show that, for all three formulations, the OS decreases considerably, indicating that samples lose their structure at lower oscillatory stress levels. The values of G and G” at the LVR also decreased with increased storage. The magnitude of the viscoelastic moduli for G was in accordance with the previously reported values for LVR some other food hydrocolloids [27]. As for the loss-tangent values (tan ), which is LVR the ratio between G and G” , all values were in the range of 0.09–0.22, indicating a LVR LVR predominantly elastic behavior. Moreover, the ﬂow point (G = G”) indicates the stress at which the ﬁrst non-linear structural change occurs. In this study, the HIPE (EF75%) had higher oscillatory stress values at the ﬂow point (21–66 Pa) compared to emulsions EF70% (5–11 Pa) and EF65% (1–4 Pa), indicating that it undergoes structural changes at higher stress values. In summary, the results of the amplitude sweep test determined the structural strength and allowed us to distinguish between weaker and stronger gels. EF75% was the strongest gel throughout storage as it remained in the LVE region (higher OS ) for a longer period of time, and it presented higher G (Pa), G” (Pa), FP (Pa), and FP (Pa). The results LVR LVR OS G also demonstrate that, with the increase in storage days, the strength of the entire system decreased. Nonetheless, it can be assumed that EF75% is the most stable system, as it is the strongest gel, followed by EF70% and EF65%. Frequency Sweep To further investigate the viscous and elastic behavior changes under increased fre- quency applications, a frequency sweep analysis at 0.1 Pa (within the LVR for all samples and days) was conducted (Figure 3c). Throughout the 60 days of storage for all samples, no 0 0 crossover point (G = G”) was detected and G was always higher than G” (data not shown). These results indicate that, within the tested experimental range (0.01–10 Hz), all samples displayed gel-like behavior—more similar to a solid rather than a liquid. Therefore, the deformations can be considered as essentially elastic and recoverable [28]. Moreover, the results suggest that, even at higher frequencies, the rheological responses of both emulsion Foods 2022, 11, 1588 11 of 15 and the HIPE have no obvious effect by the applied deformation rate. This behavior was also observed in other studies in the literature [25,28]. At a ﬁxed frequency of 1 Hz, the tan values of EF75%, EF70%, and EF65% were within the ranges of 0.08–0.14, 0.12–0.18, and 0.16–0.22, respectively, indicating that all the samples were more elastic than viscous throughout the 60 days of storage (Table 4). In addition, it can be noted that the EF75% had the lowest values of tan, indicating that it has a stronger gel structure, which is in accordance with the apparent viscosity and amplitude sweep tests. 0 0 0 Table 4. Power law parameters (k and n ) for the storage modulus G throughout the 60 days of storage at 25 C and the storage (G ) and loss (G” ) moduli; the loss-tangent (tan) at a frequency LVR of 1 Hz for samples stored at 25 C. ’ ’ n Model Parameters (G =k w ) Experimental Parameters 0 n 0 2 0 Samples Storage (d) k (Pas ) n R G (Pa) G” (Pa) tan a a a ab abc 0 0.18 0.02 0.96 599 54 0.18 0.01 394 32 109 12 abc a a c a 3 461 4 0.22 0.05 0.97 718 11 134 8 0.19 0.01 c a a a bc 7 489 27 0.18 0.03 0.96 723 53 119 6 0.16 0.00 bc a a c a EF65% 14 0.19 0.02 0.97 654 89 130 13 0.20 0.04 487 30 a a ab ab a 30 367 46 0.17 0.01 0.96 546 55 96 11 0.18 0.02 d a b ab a 45 0.19 0.02 0.96 0.22 0.05 273 36 425 36 92 14 d a b a a 60 266 31 0.19 0.02 0.96 408 49 79 13 0.19 0.03 ab ab a a ab 0 0.98 1097 42 172 12 846 58 0.14 0.02 0.16 0.01 b b c b b 3 914 20 0.17 0.01 0.99 1396 163 250 40 0.18 0.03 ab ab ab ab 7 810 56 0.13 0.02 0.95 1069 37 145 27 0.14 0.02 ab ab a a ab EF70% 14 828 53 0.14 0.02 0.97 1105 109 174 36 0.16 0.02 ac a a a ab 30 731 40 0.12 0.00 0.96 972 43 115 6 0.12 0.01 a ac ab ab a ab 45 709 71 0.97 151 18 0.14 0.01 968 79 0.16 0.01 c ab b a ab 60 617 22 0.15 0.01 0.97 845 38 130 8 0.15 0.00 a a a a ab 0 1252 97 0.07 0.01 0.97 1357 51 120 29 0.09 0.02 a a ab a a 3 1244 18 0.08 0.00 0.91 1447 17 122 5 0.08 0.00 ab ab ab abc 7 1207 98 0.96 0.09 0.02 1419 80 165 36 0.12 0.03 a ab ab ab abc EF75% 14 1326 43 0.09 0.00 0.96 1502 162 182 46 0.12 0.02 a a a a abc 30 1128 82 0.08 0.01 0.97 1342 87 124 19 0.09 0.01 a b b b bc 45 1183 26 0.98 0.11 0.01 1698 224 226 19 0.13 0.01 a b ab ab c 60 1122 76 0.11 0.01 0.96 1375 89 187 28 0.14 0.01 Mean values (mean value standard derivation, n = 3) for the same parameter, sample, and column with different lower-case superscripts are signiﬁcantly different based on Tukey’s test at p < 0.05. To further investigate the frequency dependency of G values, a power law relation was applied [28,29] and the degree of frequency dependence was determined by power law parameters (Table 4). 0 0 Low n values are characteristic of elastic gels, n values near to 1 indicate that the 0 0 system behaves as a viscous gel, and at n values close to zero, the G value does not change with the frequency [28]. As can be observed in Table 4, EF75% had the lowest values of n , presenting values very close to 0. These results conﬁrm that EF75% has the least dependency on frequency changes, which can be visualized in Figure 3c, where at any given frequency G plot for EF75% barely has a slope, indicating there are minimal changes 0 0 in the G value. The highest k values were also found to be from the EF75% sample, which means that these samples had stronger elastic structures than the others. This value also decreased with the increase in storage days for all samples (except for EF75%), which can be attributed to the formation of a weaker network. Foods 2022, 11, 1588 12 of 15 Temperature Sweep To determine the sensitivity of the sample structure to thermal changes, a temperature sweep was conducted. All samples had predominance of elastic behavior over the viscous (G > G”) and formed structured gels with different strengths. No melting was detected as G did not equal G” in the entire temperature range evaluated, indicating that all samples remained in a solid-like state. From 10 C to around 40 C, all samples showed a slight G and G” decrease. However, at temperatures above 40 C, an increase in G and G” values was observed for both emulsions (EF65% and EF70%), behavior which was observed only slightly in the HIPE (EF75%) (Figure 4). This increase in G can be related to the development and transformation of the liquid state into a gel state (sol–gel transition) and/or due to the thickening effect of the starches leached out from the chickpea seed, which restricts the mobility of ﬂuids. [28]. Similar results were obtained in other studies Foods 2022, 11, x FOR PEER REVIEW 13 of 15 using protein, such as with whey protein emulsions [30] and emulsion gels stabilized by pea ﬂour [31]. Figure 4. Temperature sweeps (heating) for EΦ65%, EΦ70%, and EΦ75% throughout 60 days storage Figure 4. Temperature sweeps (heating) for EF65%, EF70%, and EF75% throughout 60 days storage at 25 °C. at 25 C. 3.4. Conventional Emulsions and HIPE Stability Within the days of storage, it was possible to observe that, for EF65%, already after day 0, G started to considerably increase, followed by a sharp decrease (Figure 4). Following Following centrifugation, all the samples were separated into three layers as was re- day 14, G even became higher than EF70%. This behavior was not observed in EF70% ported in previous studies with protein HIPEs [16,33,34]. The top layer consisted of the oil and EF75%, which remained with similar behaviors in every temperature scan throughout fraction and was quantified in terms of oil loss upon centrifugation (Figure 5a). The mid- the 60 days of storage. dle layer consisted of a cream layer and the bottom layer was an aqueous phase. Up to The structure of the studied emulsions and HIPE was evaluated through a correlation storage day 14, the oil loss was higher at the higher oil concentration (EΦ75% > EΦ70% > 0 0 0 between G and G” (G /G). At a G /G” ratio lower than 10, the gel is considered a weak EΦ65%). These results may be related to structuring agent concentration, as there was gel; whereas, if this value is above 10, the gel is considered a strong gel [32]. At the probably not enough structurant available to be adsorbed on the surface of oil droplets at maximum temperature of analysis (80 C), the calculation for the gel strength of these higher oil concentrations. Interestingly, after 14 d of storage, the oil loss was considerably systems was performed. The ratios were 7.5, 5.8, and 4.6, for EF75%, EF70%, and EF65%, reduced, indicating that a rearrangement might have occurred. Although the oil loss upon respectively, on day 0, indicating that the gel strength of the samples increased at higher centrifugation showed a significant difference (p < 0.05) by the Tukey’s test, the variation concentrations of oil. In summary, a higher F concentration increased the apparent viscosity between days 0 and 30 did not exceed 1.5, 0.3, and 0.2% for EΦ75%, EΦ70%, and EΦ65%, and viscoelasticity of both emulsions and the HIPE. respectively, which can be considered quite low. Figure 5. Oil loss upon centrifugation throughout 60 days of storage at 25 °C (a) and appearance of samples after centrifugation (b). Mean values (mean value ± standard derivation, n = 3) for the same parameter, sample, and column with different lower-case superscripts are significantly different based on Tukey’s test at p < 0.05. 4. Conclusions Foods 2022, 11, x FOR PEER REVIEW 13 of 15 Foods 2022, 11, 1588 13 of 15 Figure 4. Temperature sweeps (heating) for EΦ65%, EΦ70%, and EΦ75% throughout 60 days storage at 25 °C. 3.4. Conventional Emulsions and HIPE Stability 3.4. Conventional Emulsions and HIPE Stability Following centrifugation, all the samples were separated into three layers as was re- Following centrifugation, all the samples were separated into three layers as was re- ported in previous studies with protein HIPEs [16,33,34]. The top layer consisted of the oil ported in previous studies with protein HIPEs [16,33,34]. The top layer consisted of the oil fraction and was quantified in terms of oil loss upon centrifugation (Figure 5a). The mid- fraction and was quantiﬁed in terms of oil loss upon centrifugation (Figure 5a). The middle dle layer consisted of a cream layer and the bottom layer was an aqueous phase. Up to layer consisted of a cream layer and the bottom layer was an aqueous phase. Up to storage day storag 14,ethe day oil 14 loss , the was oil l higher oss waat s h the ighhigher er at th oil e h concentration igher oil conc(E enF tr75% ation> (E EΦF75% 70% > > E EΦF7 65%) 0% > . These EΦ65% results ). Thesmay e resbe ults r elated may bto e rstr ela ucturing ted to str agent ucturiconcentration, ng agent conce as ntr ther atioe n,was as tpr heobably re was not enough structurant available to be adsorbed on the surface of oil droplets at higher probably not enough structurant available to be adsorbed on the surface of oil droplets at oil concentrations. Interestingly, after 14 d of storage, the oil loss was considerably re- higher oil concentrations. Interestingly, after 14 d of storage, the oil loss was considerably duced, indicating that a rearrangement might have occurred. Although the oil loss upon reduced, indicating that a rearrangement might have occurred. Although the oil loss upon centrifugation showed a signiﬁcant difference (p < 0.05) by the Tukey’s test, the variation centrifugation showed a significant difference (p < 0.05) by the Tukey’s test, the variation between days 0 and 30 did not exceed 1.5, 0.3, and 0.2% for EF75%, EF70%, and EF65%, between days 0 and 30 did not exceed 1.5, 0.3, and 0.2% for EΦ75%, EΦ70%, and EΦ65%, respectively, which can be considered quite low. respectively, which can be considered quite low. Figure 5. Oil loss upon centrifugation throughout 60 days of storage at 25 °C (a) and appearance of Figure 5. Oil loss upon centrifugation throughout 60 days of storage at 25 C (a) and appearance samples after centrifugation (b). Mean values (mean value ± standard derivation, n = 3) for the same of samples after centrifugation (b). Mean values (mean value standard derivation, n = 3) for the parameter, sample, and column with different lower-case superscripts are significantly different same parameter, sample, and column with different lower-case superscripts are signiﬁcantly different based on Tukey’s test at p < 0.05. based on Tukey’s test at p < 0.05. 4. Conclusions 4. Conclusions In this study, solely chickpea aquafaba at different oil phase volumes (F) of canola oil were used to produce stable emulsions and HIPE. The results indicate that the emulsions resist prolonged storage without breakdown through physical instability mechanisms. In terms of the rheological properties, all samples showed gel-like behavior throughout 60 days of storage at 25 C. Moreover, the rheological tests showed a weakening of the gel’s strength throughout storage. Among the three studied formulations, EF75% showed to be the most stable system in terms of droplet size and rheological properties. In addition, samples had less than 1.5% of oil loss after centrifugation, which indicated that all samples had very good centrifugation stability. The outcome of this study produced an inexpensive potential substitute for saturated and trans-fat for food products, in addition to the valuable utilization of biowaste from the food industry and its conversion into a high value food ingredient. Moreover, the CA-based emulsions and HIPE did not require any modiﬁcation method prior to production (i.e., sonication) nor further cumbersome processes (i.e., gelling, complexing, and heating) or the use of expensive equipment, and thus no high additional operational costs. Nonetheless, to study the feasibility and acceptability of using these systems as a fat replacer, there is a need for application in a food system, as well as consumer sensory analysis. Author Contributions: Conceptualization, G.G.B.K.; methodology, G.G.B.K.; formal analysis, G.G.B.K. and A.M.M.T.G.; investigation, G.G.B.K.; resources, G.G.B.K. and M.D.H.; writing—original draft preparation, G.G.B.K.; writing—review and editing, G.G.B.K. and M.D.H.; visualization, G.G.B.K.; project administration, G.G.B.K.; funding acquisition, G.G.B.K. and M.D.H. All authors have read and agreed to the published version of the manuscript. Foods 2022, 11, 1588 14 of 15 Funding: The authors are grateful to São Paulo Research Foundation (FAPESP, grant #2020/05074-6, #2021/06863-7 and #2019/27354-3) and to the National Council for Scientiﬁc and Technological Development (CNPq, grant #428644/2018-0 and #309022/2021-5) for project ﬁnancial support. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: The data used in this study are available in this article. Acknowledgments: The authors acknowledge the kind donation of chickpea BRS Aleppo by EM- BRAPA Vegetables. Conﬂicts of Interest: The authors declare no conﬂict of interest. References 1. He, Y.; Purdy, S.K.; Tse, T.J.; Taran, B.; Meda, V.; Reaney, M.J.T.; Mustafa, R. Standardization of Aquafaba Production and Application in Vegan Mayonnaise Analogs. Foods 2021, 10, 1978. [CrossRef] [PubMed] 2. He, Y.; Shim, Y.Y.; Shen, J.; Kim, J.H.; Cho, J.Y.; Hong, W.S.; Meda, V.; Reaney, M.J.T. Aquafaba from Korean Soybean II: Physicochemical Properties and Composition Characterized by NMR Analysis. Foods 2021, 10, 2589. [CrossRef] [PubMed] 3. Damian, J.J.; Huo, S.; Serventi, L. Phytochemical Content and Emulsifying Ability of Pulses Cooking Water. Eur. Food Res. Technol. 2018, 244, 1647–1655. [CrossRef] 4. Stantiall, S.E.; Dale, K.J.; Calizo, F.S.; Serventi, L. Application of Pulses Cooking Water as Functional Ingredients: The Foaming and Gelling Abilities. Eur. Food Res. Technol. 2018, 244, 97–104. [CrossRef] 5. Shim, Y.Y.; He, Y.; Kim, J.H.; Cho, J.Y.; Meda, V.; Hong, W.S.; Shin, W.-S.; Kang, S.J.; Reaney, M.J.T. Aquafaba from Korean Soybean I: A Functional Vegan Food Additive. Foods 2021, 10, 2433. [CrossRef] 6. He, Y.; Shim, Y.Y.; Mustafa, R.; Meda, V.; Reaney, M.J.T. Chickpea Cultivar Selection to Produce Aquafaba with Superior Emulsion Properties. Foods 2019, 8, 685. [CrossRef] 7. He, Y.; Meda, V.; Reaney, M.J.T.; Mustafa, R. Aquafaba, a New Plant-Based Rheological Additive for Food Applications. Trends Food Sci. Technol. 2021, 111, 27–42. [CrossRef] 8. Alsalman, F.B.; Ramaswamy, H.S. Evaluation of Changes in Protein Quality of High-Pressure Treated Aqueous Aquafaba. Molecules 2021, 26, 234. [CrossRef] 9. Alsalman, F.B.; Tulbek, M.; Nickerson, M.; Ramaswamy, H.S. Evaluation and Optimization of Functional and Antinutritional Properties of Aquafaba. Legume Sci. 2020, 2, e30. [CrossRef] 10. Buhl, T.F.; Christensen, C.H.; Hammershøj, M. Aquafaba as an Egg White Substitute in Food Foams and Emulsions: Protein Composition and Functional Behavior. Food Hydrocoll. 2019, 96, 354–364. [CrossRef] 11. Lafarga, T.; Villaró, S.; Bobo, G.; Aguiló-Aguayo, I. Optimisation of the PH and Boiling Conditions Needed to Obtain Improved Foaming and Emulsifying Properties of Chickpea Aquafaba Using a Response Surface Methodology. Int. J. Gastron. Food Sci. 2019, 18, 100177. [CrossRef] 12. Huang, S.; Liu, Y.; Zhang, W.; Dale, K.J.; Liu, S.; Zhu, J.; Serventi, L. Composition of Legume Soaking Water and Emulsifying Properties in Gluten-Free Bread. Food Sci. Technol. Int. 2017, 24, 232–241. [CrossRef] [PubMed] 13. Tan, C.; McClements, D.J. Application of Advanced Emulsion Technology in the Food Industry: A Review and Critical Evaluation. Foods 2021, 10, 812. [CrossRef] [PubMed] 14. Xu, Y.-T.; Tang, C.-H.; Binks, B.P. High Internal Phase Emulsions Stabilized Solely by a Globular Protein Glycated to Form Soft Particles. Food Hydrocoll. 2020, 98, 105254. [CrossRef] 15. Vélez-Erazo, E.M.; Bosqui, K.; Rabelo, R.S.; Kurozawa, L.E.; Hubinger, M.D. High Internal Phase Emulsions (HIPE) Using Pea Protein and Different Polysaccharides as Stabilizers. Food Hydrocoll. 2020, 105, 105775. [CrossRef] 16. Zuo, Z.; Zhang, X.; Li, T.; Zhou, J.; Yang, Y.; Bian, X.; Wang, L. High Internal Phase Emulsions Stabilized Solely by Sonicated Quinoa Protein Isolate at Various PH Values and Concentrations. Food Chem. 2022, 378, 132011. [CrossRef] 17. Horwitz, W. Ofﬁcial Method of Analysis, 13th ed.; Association of Analytical Chemists: Washington, DC, USA, 1980. 18. Bligh, E.G.; Dyer, W.J. A Rapid Method of Total Lipid Extraction and Puriﬁcation. Can. J. Biochem. Physiol. 1959, 37, 911–917. [CrossRef] 19. Meurer, M.C.; de Souza, D.; Marczak, L.D.F. Effects of Ultrasound on Technological Properties of Chickpea Cooking Water (Aquafaba). J. Food Eng. 2020, 265, 109688. [CrossRef] 20. Shim, Y.Y.; Mustafa, R.; Shen, J.; Ratanapariyanuch, K.; Reaney, M.J.T. Composition and Properties of Aquafaba: Water Recovered from Commercially Canned Chickpeas. J. Vis. Exp. 2018, 132, e56305. [CrossRef] 21. Raikos, V.; Hayes, H.; Ni, H. Aquafaba from Commercially Canned Chickpeas as Potential Egg Replacer for the Development of Vegan Mayonnaise: Recipe Optimisation and Storage Stability. Int. J. Food Sci. Technol. 2020, 55, 1935–1942. [CrossRef] 22. Mustafa, R.; He, Y.; Shim, Y.Y.; Reaney, M.J.T. Aquafaba, Wastewater from Chickpea Canning, Functions as an Egg Replacer in Sponge Cake. Int. J. Food Sci. Technol. 2018, 53, 2247–2255. [CrossRef] Foods 2022, 11, 1588 15 of 15 23. Raikos, V.; Juskaite, L.; Vas, F.; Hayes, H.E. Physicochemical Properties, Texture, and Probiotic Survivability of Oat-Based Yogurt Using Aquafaba as a Gelling Agent. Food Sci. Nutr. 2020, 8, 6426–6432. [CrossRef] [PubMed] 24. Alajaji, S.A.; El-Adawy, T.A. Nutritional Composition of Chickpea (Cicer arietinum L.) as Affected by Microwave Cooking and Other Traditional Cooking Methods. J. Food Compos. Anal. 2006, 19, 806–812. [CrossRef] 25. Guo, B.; Hu, X.; Wu, J.; Chen, R.; Dai, T.; Liu, Y.; Luo, S.; Liu, C. Soluble Starch/Whey Protein Isolate Complex-Stabilized High Internal Phase Emulsion: Interaction and Stability. Food Hydrocoll. 2021, 111, 106377. [CrossRef] 26. Gomes, A.; Costa, A.L.R.; de Assis Perrechil, F.; da Cunha, R.L. Role of the Phases Composition on the Incorporation of Gallic Acid in O/W and W/O Emulsions. J. Food Eng. 2016, 168, 205–214. [CrossRef] 27. Vélez-Erazo, E.M.; Bosqui, K.; Rabelo, R.S.; Hubinger, M.D. Effect of PH and Pea Protein: Xanthan Gum Ratio on Emulsions with High Oil Content and High Internal Phase Emulsion Formation. Molecules 2021, 26, 5646. [CrossRef] 28. Hesarinejad, M.A.; Koocheki, A.; Razavi, S.M.A. Dynamic Rheological Properties of Lepidium Perfoliatum Seed Gum: Effect of Concentration, Temperature and Heating/Cooling Rate. Food Hydrocoll. 2014, 35, 583–589. [CrossRef] 29. Youseﬁ, A.R.; Razavi, S.M.A. Dynamic Rheological Properties of Wheat Starch Gels as Affected by Chemical Modiﬁcation and Concentration. Starch—Stärke 2015, 67, 567–576. [CrossRef] 30. Domian, E.; Manko-Jurkowska, ´ D. The Effect of Homogenization and Heat Treatment on Gelation of Whey Proteins in Emulsions. J. Food Eng. 2022, 319, 110915. [CrossRef] 31. Sridharan, S.; Meinders, M.B.J.; Sagis, L.M.C.; Bitter, J.H.; Nikiforidis, C. v Starch Controls Brittleness in Emulsion-Gels Stabilized by Pea Flour. Food Hydrocoll. 2022, 131, 107708. [CrossRef] 32. Dos Santos Carvalho, J.D.; Rabelo, R.S.; Hubinger, M.D. Thermo-Rheological Properties of Chitosan Hydrogels with Hydrox- ypropyl Methylcellulose and Methylcellulose. Int. J. Biol. Macromol. 2022, 209, 367–375. [CrossRef] [PubMed] 33. Wijaya, W.; van der Meeren, P.; Wijaya, C.H.; Patel, A.R. High Internal Phase Emulsions Stabilized Solely by Whey Protein Isolate-Low Methoxyl Pectin Complexes: Effect of PH and Polymer Concentration. Food Funct. 2017, 8, 584–594. [CrossRef] [PubMed] 34. Zhou, F.-Z.; Huang, X.-N.; Wu, Z.; Yin, S.-W.; Zhu, J.; Tang, C.-H.; Yang, X.-Q. Fabrication of Zein/Pectin Hybrid Particle- Stabilized Pickering High Internal Phase Emulsions with Robust and Ordered Interface Architecture. J. Agric. Food Chem. 2018, 66, 11113–11123. [CrossRef] [PubMed] http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Foods Multidisciplinary Digital Publishing Institute http://www.deepdyve.com/lp/multidisciplinary-digital-publishing-institute/storage-stability-of-conventional-and-high-internal-phase-emulsions-WJVS8C0x6G

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References (35)

E. Vélez-Erazo, Karina Bosqui, Renata Rabelo, M. Hubinger (2021)
Effect of pH and Pea Protein: Xanthan Gum Ratio on Emulsions with High Oil Content and High Internal Phase Emulsion Formation
Molecules, 26
Yue He, Y. Shim, R. Mustafa, V. Meda, M. Reaney (2019)
Chickpea Cultivar Selection to Produce Aquafaba with Superior Emulsion Properties
Foods, 8
Mariana Meurer, Daiana Souza, L. Marczak (2020)
Effects of ultrasound on technological properties of chickpea cooking water (aquafaba)
Journal of Food Engineering, 265
(1980)
Official Method of Analysis
Vassilios Raikos, Lina Juškaitė, F. Vas, H. Hayes (2020)
Physicochemical properties, texture, and probiotic survivability of oat‐based yogurt using aquafaba as a gelling agent
Food Science & Nutrition, 8
(1980)
Official Method of Analysis, 13th ed.; Association of Analytical Chemists
Y. Shim, Yue He, J. Kim, J. Cho, V. Meda, W. Hong, W. Shin, Sang Kang, M. Reaney (2021)
Aquafaba from Korean Soybean I: A Functional Vegan Food Additive
Foods, 10
Simha Sridharan, M. Meinders, L. Sagis, J. Bitter, C. Nikiforidis (2022)
Brittle emulsion-gels via heating emulsions stabilized with native pea flour
Food Hydrocolloids
Zhongyu Zuo, Xinxia Zhang, Ting Li, Jian-qiang Zhou, Yang Yang, Xiaobo Bian, Li Wang (2022)
High internal phase emulsions stabilized solely by sonicated quinoa protein isolate at various pH values and concentrations.
Food chemistry, 378
Sophie Stantiall, Kylie Dale, Faith Calizo, L. Serventi (2017)
Application of pulses cooking water as functional ingredients: the foaming and gelling abilities
European Food Research and Technology, 244
Juliana Carvalho, Renata Rabelo, M. Hubinger (2022)
Thermo-rheological properties of chitosan hydrogels with hydroxypropyl methylcellulose and methylcellulose.
International journal of biological macromolecules
T. Lafarga, Silvia Villaró, Gloria Bobo, I. Aguiló‐Aguayo (2019)
Optimisation of the pH and boiling conditions needed to obtain improved foaming and emulsifying properties of chickpea aquafaba using a response surface methodology
International Journal of Gastronomy and Food Science, 18
M. Hesarinejad, A. Koocheki, S. Razavi (2014)
Dynamic rheological properties of Lepidium perfoliatum seed gum: Effect of concentration, temperature and heating/cooling rate
Food Hydrocolloids, 35
Yue He, Sarah Purdy, T. Tse, B. Tar’an, V. Meda, M. Reaney, R. Mustafa (2021)
Standardization of Aquafaba Production and Application in Vegan Mayonnaise Analogs
Foods, 10
E. Vélez-Erazo, Karina Bosqui, Renata Rabelo, L. Kurozawa, M. Hubinger (2020)
High internal phase emulsions (HIPE) using pea protein and different polysaccharides as stabilizers
Food Hydrocolloids, 105
E. Domian, Diana Mańko-Jurkowska (2021)
The effect of homogenization and heat treatment on gelation of whey proteins in emulsions
Journal of Food Engineering
S. Huang, Yuling Liu, Weihan Zhang, Kylie Dale, Silu Liu, Jingnan Zhu, L. Serventi (2018)
Composition of legume soaking water and emulsifying properties in gluten-free bread
Food Science and Technology International, 24
E. Bligh, Dyer W.J.A. (1959)
A rapid method of total lipid extraction and purification.
Canadian journal of biochemistry and physiology, 37 8
Y. Shim, R. Mustafa, Jianheng Shen, Kornsulee Ratanapariyanuch, M. Reaney (2018)
Composition and Properties of Aquafaba: Water Recovered from Commercially Canned Chickpeas.
Journal of visualized experiments : JoVE, 132
R. Mustafa, Yue He, Y. Shim, M. Reaney (2018)
Aquafaba, wastewater from chickpea canning, functions as an egg replacer in sponge cake
International Journal of Food Science & Technology, 53
Fu-Zhen Zhou, Xiao-Nan Huang, Zi-Ling Wu, S. Yin, Jian-hua Zhu, Chuan-he Tang, Xiaoquan Yang (2018)
Fabrication of Zein/Pectin Hybrid Particle-Stabilized Pickering High Internal Phase Emulsions with Robust and Ordered Interface Architecture.
Journal of agricultural and food chemistry, 66 42
Yan-Teng Xu, Chuan-he Tang, B. Binks (2020)
High internal phase emulsions stabilized solely by a globular protein glycated to form soft particles
Food Hydrocolloids, 98
Yue He, Y. Shim, Jianheng Shen, J. Kim, J. Cho, W. Hong, V. Meda, M. Reaney (2021)
Aquafaba from Korean Soybean II: Physicochemical Properties and Composition Characterized by NMR Analysis
Foods, 10
Saleh Alajaji, T. El-Adawy (2006)
Nutritional composition of chickpea (Cicer arietinum L.) as affected by microwave cooking and other traditional cooking methods
Journal of Food Composition and Analysis, 19
Chen Tan, D. Mcclements (2021)
Application of Advanced Emulsion Technology in the Food Industry: A Review and Critical Evaluation
Foods, 10
Fatemah Alsalman, H. Ramaswamy (2021)
Evaluation of Changes in Protein Quality of High-Pressure Treated Aqueous Aquafaba
Molecules, 26
Tina Buhl, C. Christensen, M. Hammershøj (2019)
Aquafaba as an egg white substitute in food foams and emulsions: Protein composition and functional behavior
Food Hydrocolloids
Yue He, V. Meda, M. Reaney, R. Mustafa (2021)
Aquafaba, a new plant-based rheological additive for food applications
Trends in Food Science and Technology, 111
Vassilios Raikos, H. Hayes, He Ni (2020)
Aquafaba from commercially canned chickpeas as potential egg replacer for the development of vegan mayonnaise: recipe optimisation and storage stability
International Journal of Food Science & Technology
Andresa Gomes, A. Costa, F. Perrechil, R. Cunha (2016)
Role of the phases composition on the incorporation of gallic acid in O/W and W/O emulsions
Journal of Food Engineering, 168
Fatemah Alsalman, M. Tulbek, M. Nickerson, H. Ramaswamy (2020)
Evaluation and optimization of functional and antinutritional properties of aquafaba
Legume Science, 2
Jane Damian, Siyu Huo, L. Serventi (2018)
Phytochemical content and emulsifying ability of pulses cooking water
European Food Research and Technology, 244
Wahyu Wijaya, P. Meeren, C. Wijaya, Ashok Patel (2017)
High internal phase emulsions stabilized solely by whey protein isolate-low methoxyl pectin complexes: effect of pH and polymer concentration.
Food & function, 8 2
A. Yousefi, S. Razavi (2015)
Dynamic rheological properties of wheat starch gels as affected by chemical modification and concentration
Starch-starke, 67
Baozhong Guo, Xiuting Hu, Jianyong Wu, Rui-yun Chen, Taotao Dai, Yunfei Liu, S. Luo, Cheng-mei Liu (2021)
Soluble starch/whey protein isolate complex-stabilized high internal phase emulsion: Interaction and stability
Food Hydrocolloids, 111

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Abstract

foods Article Storage Stability of Conventional and High Internal Phase Emulsions Stabilized Solely by Chickpea Aquafaba Graziele Grossi Bovi Karatay * , Andrêssa Maria Medeiros Theóphilo Galvão and Miriam Dupas Hubinger Department of Food Engineering and Technology, School of Food Engineering, University of Campinas (UNICAMP), Monteiro Lobato Street, 80, Campinas 13083-862, Brazil; [email protected] (A.M.M.T.G.); [email protected] (M.D.H.) * Correspondence: [email protected] Abstract: Aquafaba is a liquid residue of cooked pulses, which is generally discarded as waste. However, it is rich in proteins and, thus, can be used as a plant-based emulsiﬁer to structure vegetable oil. This study investigates chickpea aquafaba (CA) as an agent to structure different oil phase volumes (F) of canola oil (CO). CO was structured in the form of conventional emulsions (EF65% and EF70%) and high internal phase emulsion (HIPE) (EF75%) by the one-pot homogenization method. Emulsions were evaluated for a period of 60 days at 25 C in terms of average droplet size (11.0–15.9 m), microscopy, rheological properties, and oil loss (<1.5%). All systems presented predominantly elastic behavior and high resistance to coalescence. EF75% was the most stable system throughout the 60 days of storage. This study developed an inexpensive and easy to prepare potential substitute for saturated and trans-fat in food products. Moreover, it showed a valuable utilization of an often-wasted by-product and its conversion into a food ingredient. Citation: Grossi Bovi Karatay, G.; Medeiros Theóphilo Galvão, A.M.; Keywords: pulses; emulsiﬁer; stabilizers; oil structuring; HIPE; aquafaba Dupas Hubinger, M. Storage Stability of Conventional and High Internal Phase Emulsions Stabilized Solely by Chickpea Aquafaba. Foods 2022, 11, 1. Introduction 1588. https://doi.org/10.3390/ Cooking pulse seeds in water, canning, as well as hummus production, yields an foods11111588 inexpensive, viscous, rich liquid called aquafaba [1,2]. Aquafaba is an eco-friendly by- Academic Editors: Arun K. Bhunia, product, rich in nutrients, with vast potential to be used as a food ingredient due to its Joana S. Amaral, Derek V. Byrne, emulsibility, foamability, gelation, and thickening properties [2]. Aquafaba’s properties are Theodoros Varzakas, Esther Sendra attributed to its composition consisting of protein, polysaccharide, polysaccharide-protein and Benu P. Adhikari complexes, coacervates, saponins, and phenolic compounds [1,3–5]. This composition comes from the components transferred from seed to water during cooking, as well as from Received: 5 May 2022 Accepted: 27 May 2022 the interactions between these components under high pressure and temperature [6–8]. Published: 28 May 2022 Moreover, this composition is greatly inﬂuenced by pulse cultivar and cooking and soaking conditions [6]. Publisher’s Note: MDPI stays neutral Using aquafaba as a food ingredient is a “win–win–win–win” situation as (i) it is with regard to jurisdictional claims in environmentally sustainable since it enables the utilization of a by-product that is generally published maps and institutional afﬁl- discarded by end consumers; (ii) it is nutrient rich; (iii) it is a cheaper source of protein when iations. compared to animal-based- and plant-based-protein concentrates, isolates, and hydrolysate; and (iv) it is suitable for vegan products, for which the market is expected to rapidly expand in the upcoming years. Additionally, the use of aquafaba is in line with the trend of green Copyright: © 2022 by the authors. and clean labeling, and it is promising for a broad acceptance from a consumer awareness Licensee MDPI, Basel, Switzerland. point of view. This article is an open access article The emulsifying activity, capacity, and stability of chickpea aquafaba (CA) has been distributed under the terms and reported in various studies [5,9,10]. He et al. [6] evaluated different chickpea cultivars to conditions of the Creative Commons assess its inﬂuence on the emulsiﬁcation properties of CA-based emulsions with an oil phase Attribution (CC BY) license (https:// volume (F) of 70%. The authors reported that the emulsion capacity and stability among creativecommons.org/licenses/by/ the ﬁve chickpea cultivars ranged from 1.10 to 1.30 m /g and 71.9 to 77.1%, respectively. 4.0/). Foods 2022, 11, 1588. https://doi.org/10.3390/foods11111588 https://www.mdpi.com/journal/foods Foods 2022, 11, 1588 2 of 15 Lagarfa et al. [11] evaluated the inﬂuence of pH (3.5, 5, and 6.5) and chickpea-to-water ratio (1:1.5 to 1:5.0) during cooking on the emulsifying capacity of CA-based emulsions (F = 60%). The authors reported values within the range of 3.9–72.3% for emulsion capacity and 0.0–76.3% for emulsion stability, whereas Huang et al. [12] reported a 46% emulsifying activity of CA-based emulsions (F = 50%). The results from these different studies show the important role pH, chickpea/water ratio, F, and cultivars play on the emulsifying properties of CA-based emulsions. Even though there have been reports on CA emulsifying properties, emulsion proper- ties have only been partly elucidated and there is no in-depth study evaluating the stability of CA-based structured oils produced with different oil phase volumes over longer periods of storage. It is well known that one of the most difﬁcult problems to solve in emulsiﬁ- cation technology is the creation of stable emulsion structures that can resist prolonged storage without breakdown through physical instability mechanisms, such as gravitational separation and droplet aggregation [13]. Therefore, it is necessary to study such systems for longer storage periods in terms of its physicochemical and rheological behaviors to adequately evaluate its potential as a fat replacer. Among the different emulsion types, high internal phase emulsions (HIPEs) have at- tracted considerable interest to be used in food applications due to their elevated fat/water content (minimal F of 74%) and adjustable viscoelasticity [13,14]. One important appli- cation of HIPEs is as an alternative to partially hydrogenated oils (PHOs), and, in turn, trans-fatty acids (TFAs) as hydrogenation leads to the production of TFAs [13]. Recently, protein-stabilized HIPEs have been developed using a simple one-pot homogenization method, in which mixtures of oil and aqueous protein solution are sheared for short times [14–16]. In this context, this study aims to evaluate the use of chickpea aquafaba (CA) from a Brazilian cultivar (BRS Aleppo) as a structuring agent to structure canola oil (CO) in the form of conventional emulsions and HIPE through the one-pot homogenization method and its storage stability for a period of 60 days at 25 C. 2. Materials and Methods 2.1. Materials A kabuli type chickpea cultivar (Cicer arietinum (L.), var. BRS Aleppo) was kindly donated by Embrapa Vegetables (Brasilia, Brazil). All the seeds were frozen until the analyses. Canola oil (CO) (purity 100%; Seara Alimentos S.A, Sao Paulo, Brazil) was bought in a local supermarket (Dalben, Campinas, Brazil). Nile red, ﬂuorescein isothiocyanate (FITC) and sodium azide were obtained from Sigma-Aldrich (St. Louis, MO, USA) and all other chemical reagents were of analytical grade. 2.2. Chickpea Aquafaba (CA) Production First, the chickpea seed was manually cleaned to remove broken seed, dust, and other foreign materials. Then, 400 g of seed was presoaked in distilled water at a chickpea:water ratio of 1:3 (w/w) for 16 h at 5 C. Subsequently, 400 g of presoaked seed was rinsed with distilled water and mixed with distilled water at a chickpea:water ratio of 1:2 and cooked in a pressure cooker (Instant Pot 7 in 1 multi-use programmable pressure cooker, IPDUO60 V2, 6 quart/liters) at 115–118 C (an autogenic pressure range of 70–80 kPa) for 30 min. These conditions were chosen based on a previously reported study that evaluated the optimum conditions for producing CA with the best emulsion quality [1]. Following cooking, the cooked chickpeas were kept in the cooking pot for 6 h. The CA was then drained using a strainer and separated from the cooked chickpeas, weighed, and stored frozen until use. 2.3. CA Proximate Composition The moisture content of the CA was measured in an infrared moisture analyzer (model MOC63u, Shimadzu, Japan) at 105 C, until constant weight was reached [17]. For the determination of protein, ash, ﬁber, and fat, lyophilized CA was used, and the results were Foods 2022, 11, 1588 3 of 15 then converted to a wet basis. The total protein content of freeze-dried CA was quantiﬁed according to the Kjeldahl method using 6.25 factor for the conversion of nitrogen to protein. For ash determination, the samples were placed in previously weighed porcelain crucibles. The samples were then carbonized over a Bunsen burner and placed in a mufﬂe furnace heated to 550 C and left at this temperature for 6 h, and then transferred to a desiccator containing silica gel. After reaching room temperature, the crucibles containing the samples were weighed to determine the ash content by mass difference according to AOAC Ofﬁcial Method 923.03. For crude ﬁber determination, a modiﬁed Weende procedure was used. In short, the samples were ﬁrst boiled in sulfuric acid (1.25%) for the extraction of sugar and starch (acid digestion). The samples were then ﬁltered and washed with water to remove acid residues and neutralize the pH. Subsequently, the samples were boiled with 1.25% sodium hydroxide to remove proteins, hemicellulose, and lignin (alkali digestion). The samples were again ﬁltered and washed with water to remove alkali residues and neutralize the pH. The samples and ﬁlter were then dried at 100 C and then at 550 C in a mufﬂe furnace. Crude ﬁber was then determined by mass difference (AOAC Ofﬁcial method 930.10). The extraction of the lipid fraction was performed in accordance with the methodology described by Bligh and Dyer [18]. The total carbohydrate content was calculated as the difference between 100 and the sum of the percentage of moisture, ash, lipid, and protein. All chemical analyses were performed in three replications. 2.4. Conventional Emulsions and HIPE Production Conventional emulsions and HIPE formulated with CO and CA containing a con- centration of 0.05% (w/w) of sodium azide (for the inhibition of growth of microorgan- isms) were prepared by a one-pot homogenization method using a rotor-stator device ® ® (Ultraturrax T18 basic, IKA -Werke GmbH & Co., KG, Staufen, Germany) operating at 15.500 rpm for 1 min. CO was structured in the form of simple emulsions, namely, EF65% (35%CA and 65%CO) and EF70% (30%CA and 70%CO), and high internal phase emulsion (HIPE), EF75% (25%CA and 75%CO). The emulsions and HIPE were produced in triplicate, stored at 25 C, and characterized on selected days until 60 days of storage were reached. 2.5. Conventional Emulsions and HIPE Characterization 2.5.1. Droplet Size The dimensions of the droplets were determined by static light scattering using Mastersizer 2000 (Malvern Instruments Limited, Worcestershire, UK). The samples were dispersed in water with a refraction index of 1.33 and a rotation velocity of 2100 rpm at room temperature (25 C). The equipment possesses a stand-alone computer that runs the Malvern software. The Malvern software controls the optical bench and dispersion units and analyzes the raw data from the optical bench to determine the size of the particles, which are presented in many different formats. In this study, the droplet size was reported in terms of size distribution, volume-weighted (D ) and surface-weighted (D ) diameters, [4,3] [3,2] and span, according to Equations (1)–(3), respectively: n d D = (1) [4,3] n d n d D = (2) [4,3] n d d d (90) (10) Span = (3) (50) where d is the droplet diameter, n the number of drops, and d , d , and d are the i (10) (50) (90) diameters at 10%, 50%, and 90% of cumulative volume. Foods 2022, 11, 1588 4 of 15 2.5.2. Optical and Confocal Laser Scanning Microscopy All the samples were imaged via optical and confocal laser scanning microscopy (CLSM) using an optical microscope (Carl Zeiss, Axio Scopo A1, Aalen, Germany) at room temperature (25 C). The images were examined in the software AxioVision Rel. 4.8 (Carl Zeis, Aalen, Germany). For ﬂuorescence analysis, the samples were stained with 10 L of Nile red (0.1 g/L in polyethylene glycol) and 10 L of FITC (0.02 g/mL in ethanol). The protein was dyed with FITC (green) and CO with Nile red. 2.5.3. Rheological Measurements The rheological measurements of the samples were determined on an AR 1500 ex (TA Instruments, New Castle, PA, USA) using a 2 stainless-steel cone and plate (40 mm diameter and 47 m gap). Apparent viscosity data as a function of shear rate were acquired by performing ﬂow curves with shear rate values ranging from 0 to 300 s , with three sequential ramps: up– down–up cycles, respectively, aiming at the elimination of thixotropy. Data from the third ﬂow curve were adjusted according to the power law model, according to Equation (4): = k g (4) where is the shear stress (Pa); k is the ﬂow consistency index (Pas ); g is the shear rate (1/s), and n is the ﬂow behavior index (dimensionless). All the measurements were performed in triplicate at 25 C on day 0 (fresh) and after 3, 7, 14, 30, 45, and 60 days of storage. The viscoelastic behavior of the emulsions and HIPE was investigated by small am- plitude oscillatory measurements. First, a stress sweep was performed by logarithmically increasing the stress from 0.01 to 100 Pa at a frequency of 1 Hz to identify the linear vis- coelastic region (LVR) of the samples. Further rheological parameters at the LVR, such as the storage (G ) and loss (G” ) modulus, the limiting value of oscillatory stress (OSL), LVR LVR the loss-tangent (tan ), and the ﬂow-point oscillatory stress (FPOS) and ﬂow-point G LVR (FPG) for all samples, were determined from the amplitude sweep measurements. Frequency sweeps of 0.01–10 Hz were subsequently performed at 25 C and a ﬁxed strain value of 0.1 Pa (within the LVR). Data from the frequency sweep were adjusted according to a power law model according to Equation (5): 0 0 n0 G = k w (5) 0 0 n where G (Pa) is the storage modulus, k (Pas ) is a constant, w (rad/s) is the oscillation 0 0 frequency, and n (dimensionless) is the slope in a log–log plot of G versus w. Both frequency and amplitude measurements were performed in triplicate at 25 C on day 0 (fresh) and after 3, 7, 14, 30, 45, and 60 days of storage. Temperature sweep tests were performed in the range of 10 to 80 C with a ﬁxed strain value within the LVR and frequency of 1 Hz. All the measurements were performed in duplicate on day 0 (fresh) and after 3, 7, 14, 30, 45, and 60 days of storage. 2.5.4. Conventional Emulsions and HIPE Stability The stability of the conventional emulsions and HIPE was quantiﬁed in terms of centrifugal oil loss. Approximately 1 g of sample was put into Eppendorfs, centrifuged at 8600 g for 30 min at 5 C. Following centrifugation, free oil was removed and the sample mass without free oil was recorded and determined according to Equation (6): m m Centrifugal oil loss (%) = 100 (6) where m is the initial mass of the sample and m is the ﬁnal mass of the sample without i f free oil. Foods 2022, 11, 1588 5 of 15 2.6. Statistical Analyses The experimental data were depicted as the means standard deviation and analyzed applying one factor analysis of variance (ANOVA) using Statistica 8.0 software (Stat Soft. Inc., Tulsa, OK, USA). Signiﬁcant differences (p < 0.05) between means were detected using the Tukey test. Graphs were obtained with Microsoft Excel Ofﬁce 2016. 3. Results and Discussion 3.1. CA Proximate Composition Chickpea hulls work as a membrane that control mass transfer during the soaking and cooking processes. When these hulls are damaged, the release of chickpea seed components (e.g., protein and carbohydrate) into the water is facilitated [6,19]. In turn, the components released from the chickpea seed into the cooking water affects the CA composition and, consequently, the functional properties of the resulting CA. Therefore, determining the proximate composition of CA is of high importance. The moisture composition of CA in this study was 94.38% 0.19 and is in accordance with other studies. Shim et al. [20] reported on the moisture content of 10 commercial canned chickpea products; the values were between 92.98% and 95.12%. He et al. [6] produced CA from 5 different cultivars under similar conditions to the present study, and the reported values were in the range of 92.4% to 94.2%. As for Raikos et al. [21], who reported on canned CA, the reported value was 94.97%. The protein content of CA in this study was 1.21% 0.04. Stantiall et al. [4] produced CA by soaking chickpea seed (CS) in a 1:3.3 weight ratio (CS:water) for 16 h and cooking in a 1:1.75 weight ratio (CS:water) for 90 min; they reported a protein content of 0.95%. In the studies of Mustafa et al. [22] and Raikos et al. [21], the protein content value reported was 1.5% and 1.3%, respectively. Bulh et al. [10], who reported on the CA composition declared by the producer (Salling Group, Brabrand, Denmark), reported a relatively high protein composition of 6.3%. As for the ash content, the determined value in this study was 0.49% 0.01, which agrees with the previously reported values in the literature, which were 0.4%, 0.5%, and 0.6% in [4,21,22], respectively. The ﬁber content of CA was reported in very few studies and was 0.69 0.03 and 4.04 0.09 in [21,23], respectively. In this study, the determined value was 0.51 0.16. The carbohydrate content in this study was 3.39 %. Mustafa et al. [22] reported a 4% CA composition for simple and complex carbohydrates; whereas, in [10], the composition of carbohydrates was considerably high (i.e., 15%). As for the fat content, in some studies, it was not detected or was below the detection limit [4,22]. However, in our study, fat content was detected and was 0.14 0.01, which is in accordance with [23], who reported a value of 0.13 0.03 and with [21], who reported a value of <0.1%. A study on boiled chickpeas [24] reported a signiﬁcant loss of small fractions of fats upon boiling. This fat loss could have undergone two processes: (i) leaching out into the cooking water, such as the case in the present study; or, (ii) the fat was degraded during processing [4]. On the other hand, in the study of [10], a high fat content of 2.2 % was reported. In summary, these differences in the proximate composition of CA are due to many factors, such as the chickpea cultivar and especially the processing conditions used to produce the aquafaba. These different compounds can be tailored to have unique functional properties according to the desired use of the AQ. In this study, this speciﬁc composition was evaluated for its ability to structure liquid oil. 3.2. Droplet Size and Confocal Laser Scanning Microscopy The droplet-size distribution for all formulations remained with a bimodal proﬁle during the 60 days of storage (Figure 1). As can be observed, there were many overlapping curves throughout storage, indicating that the emulsions resisted prolonged storage without breakdown through physical instability mechanisms. Foods 2022, 11, x FOR PEER REVIEW 6 of 15 properties according to the desired use of the AQ. In this study, this specific composition was evaluated for its ability to structure liquid oil. 3.2. Droplet Size and Confocal Laser Scanning Microscopy The droplet-size distribution for all formulations remained with a bimodal profile during the 60 days of storage (Figure 1). As can be observed, there were many overlapping Foods 2022, 11, 1588 6 of 15 curves throughout storage, indicating that the emulsions resisted prolonged storage with- out breakdown through physical instability mechanisms. Figure 1. Droplet-size distribution of (a) EΦ65%, (b) EΦ70%, and (c) EΦ75% during 60 days of stor- Figure 1. Droplet-size distribution of (a) EF65%, (b) EF70%, and (c) EF75% during 60 days of age at 25 °C. storage at 25 C. Table 1 shows the droplet size, expressed in terms of D [4,3] (based on the volume of a Table 1 shows the droplet size, expressed in terms of D (based on the volume of [4,3] asp spher heree) ) an and d DD [3,2] (b(based ased on on ththe e didiameter ameter of of a sa pspher here).e). ThThe e resru esults lts of t of hethe dro dr pl oplet et size size in tin he [3,2] the prepr seesent nt stustudy dy wewer re wi e twithin hin thethe ran ranges ges of 11. of 11.0–12.8 0–12.8 µm , m, 12.12.3–13.0 3–13.0 µm,m, and and 14.14.1–15.9 1–15.9 µm m (D (D [4,3]) an ) and d 6.5 6.5–7.0 –7.0 µm m; ; 5.5.7–6.0 7–6.0 µ m m, , an and d 5. 5.4–5.7 4–5.7 µm m ((D D [3,2])) fo for r E EΦ F75% 75%, , E EF Φ70% 70%,, and and E EF Φ65%, 65%, [4,3] [3,2] rr espectively espectively . .Although Althoughthe theaverage averagedr dr oplet opletsizes sizesshowed showeda a signiﬁcant significantdif diffe ferr ence ence( p (p< < 0.05) 0.05) as as per per the the T T ukey’s ukey’stest, test,the thevariation variation in in sizes sizes between between days days 0 0 and and 60 60 did did not not exceed exceed 1.8, 1.8, 0.7, and 1.8 m (D ) and 0.7, 0.3, and 0.3 m (D ) for EF75%, EF70%, and EF65%, 0.7, and 1.8 µm (D [4,3]) and 0.7, 0.3, and 0.3 µm (D [3,2]) for EΦ75%, EΦ70%, and EΦ65%, [4,3] [3,2] respectively, which can be considered quite low. respectively, which can be considered quite low. Table 1. Droplet mean diameter (D and D ) of the emulsions and HIPE during 60 days of Table 1. Droplet mean diameter (D [4,3] and D [3,2]) of the emulsions and HIPE during 60 days of [4,3] [3,2] storage at 25 °C. storage at 25 C. D [4,3] (µm) D [3,2] (µm) D (m) D (m) [4,3] [3,2] Day EΦ65% EΦ70% EΦ75% EΦ65% EΦ70% EΦ75% Day EF65% EF70% EF75% EF65% EF70% EF75% aA aB aC aA abB bC 0 14.1 ± 0.1 12.3 ± 0.3 11.0 ± 0.2 6.5 ± 0.1 5.9 ± 0.1 5.5 ± 0.0 aA aB aC aA abB bC 0 14.1 0.1 12.3 0.3 11.0 0.2 6.5 0.1 5.9 0.1 5.5 0.0 bcA abB abC bA bcB abC 3 15.3 ± 0.5 12.5 ± 0.2 11.4 ± 0.1 7.0 ± 0.2 6.0 ± 0.1 5.4 ± 0.0 bcA abB abC bA bcB abC 3 15.3 0.5 12.5 0.2 11.4 0.1 7.0 0.2 6.0 0.1 5.4 0.0 abA abB abC aA abB abC 7 14.4 ± 0.8 12.8 ± 0.6 11.4 ± 0.2 6.3 ± 0.4 5.9 ± 0.4 5.4 ± 0.1 abA abB abC aA abB abC 14.4 0.8 12.8 0.6 11.4 0.2 6.3 0.4 5.9 0.4 5.4 0.1 cA bB bC bA cB bC cA bB bC bA cB bC 30 15.9 ± 1.3 12.9 ± 0.6 11.5 ± 0.2 7.0 ± 0.2 6.2 ± 0.2 5.7 ± 0.1 30 15.9 1.3 12.9 0.6 11.5 0.2 7.0 0.2 6.2 0.2 5.7 0.1 acA aB aC abA abB abA ab abC B abC acA aB aC 45 45 14.6 ± 0.4 12.5 ± 0.4 11.5 ± 0.3 6.6 ± 0.2 5.7 ± 0.1 5.4 ± 0.0 14.6 0.4 12.5 0.4 11.5 0.3 6.6 0.2 5.7 0.1 5.4 0.0 abA bB cB bcA abB cC abA bB cB bcA abB cC 60 14.8 0.6 13.0 0.3 12.8 0.8 6.9 0.1 5.9 0.1 5.7 0.1 60 14.8 ± 0.6 13.0 ± 0.3 12.8 ± 0.8 6.9 ± 0.1 5.9 ± 0.1 5.7 ± 0.1 Mean Mean values value(mean s (mean value valu e standar ± stand dar derivat d deriion, vatio nn = , n 9) =for 9) the for same the saparameter me param and eter column and col with umndif wfer ith ent lower-case superscript are signiﬁcantly different based on Tukey’s test at p < 0.05. Mean values for the same different lower-case superscript are significantly different based on Tukey’s test at p < 0.05. Mean parameter and row with different upper-case superscript are signiﬁcantly different by the Tukey’s test at p < 0.05. values for the same parameter and row with different upper-case superscript are significantly dif- ferent by the Tukey’s test at p < 0.05. As compared to other studies that produced protein and protein-polysaccharide- based HIPEs using the one-pot homogenization method (under slightly different time and As compared to other studies that produced protein and protein-polysaccharide- speed operating conditions), the results of this study produced emulsions and HIPEs with based HIPEs using the one-pot homogenization method (under slightly different time and relatively smaller or comparable droplet sizes. For instance, Zuo et al. [16] produced HIPEs speed operating conditions), the results of this study produced emulsions and HIPEs with using sonicated quinoa protein isolate (QPI) and peanut oil (F = 80%) and reported D relatively smaller or comparable droplet sizes. For instance, Zuo et al. [16] produced [4,3] values within the range of 30–52 m for HIPEs fabricated by sonicated QPI at low pH HIPEs using sonicated quinoa protein isolate (QPI) and peanut oil (Φ = 80%) and reported (3 and 5) and of 14–24 m for those fabricated in neutral and alkaline conditions, which D [4,3] values within the range of 30–52 µm for HIPEs fabricated by sonicated QPI at low was the case for the present study in which the pH of aquafaba was quantiﬁed close to pH (3 and 5) and of 14–24 µm for those fabricated in neutral and alkaline conditions, neutral (6.38 0.01). In the study of Vélez-Erazo et al. [15], who produced sunﬂower oil (F = 74–96%) HIPEs with pea protein isolate and different polysaccharides (i.e., xanthan gum, carrageenan, gum Arabic, alginate, gellan gum, tara gum, locust bean gum, and pectin), D was in the range of 16.24–25.79 m (depending on the polysaccharide used). [4,3] These results show that, apart from being stable in terms of droplet size and distribution for 60 days of storage, emulsions and HIPEs produced in this study had considerably lower droplet sizes compared to other studies, which, in turn, can indicate higher stability during prolonged storage times. As for the Span values (measures of absolute width), all Foods 2022, 11, x FOR PEER REVIEW 7 of 15 which was the case for the present study in which the pH of aquafaba was quantified close to neutral (6.38 ± 0.01). In the study of Vélez-Erazo et al. [15], who produced sunflower oil (Φ = 74–96%) HIPEs with pea protein isolate and different polysaccharides (i.e., xanthan gum, carrageenan, gum Arabic, alginate, gellan gum, tara gum, locust bean gum, and pec- tin), D [4,3] was in the range of 16.24–25.79 µm (depending on the polysaccharide used). These results show that, apart from being stable in terms of droplet size and distribution for 60 days of storage, emulsions and HIPEs produced in this study had considerably lower droplet sizes compared to other studies, which, in turn, can indicate higher stability during prolonged storage times. As for the Span values (measures of absolute width), all formulations presented a value of 1.6 throughout all the storage days, except for EΦ65% at day 30 and EΦ75% at day 60, for which the span value was of 1.7. A main difference between conventional emulsions and HIPEs is that the latter is a concentrated version of conventional emulsions, and typically has an internal phase (oil Foods 2022, 11, 1588 7 of 15 or water) volume fraction exceeding 74%, which is the case for the EΦ75% formulation in this study. At such a high concentration of oil, the oil droplets are tightly packed together and may adopt non-spherical shapes [13]. Nonetheless, in this study, the oil droplets in EΦ75% were mainly spherically shaped and did not present considerable differences from formulations presented a value of 1.6 throughout all the storage days, except for EF65% at the conventional emulsions, EΦ65% and EΦ70%, which can be confirmed by confocal laser day 30 and EF75% at day 60, for which the span value was of 1.7. scanning microscopy (Figure 2). It can be observed that the oil droplets of EΦ65% in- A main difference between conventional emulsions and HIPEs is that the latter is a creased considerably throughout the 60 days of storage. This was not evident in the drop- concentrated version of conventional emulsions, and typically has an internal phase (oil let-size results (Table 1), but could be noted in the size distribution graph (Figure 1), in or water) volume fraction exceeding 74%, which is the case for the EF75% formulation in this whic study h the . fi At rssuch t peak a high (lowe concentration r droplet sizes of ) d oil, ecrthe ease oil d i dr n oplets terms ar of ere tightly lative packed volume together (%) and and the smay econadopt d peaknon-spherical (higher drople shapes t sizes) [13 inc ].re Nonetheless, ased at longein r sthis torag study e day , s the (i.e oil ., ddr ay oplets s 45 an in d EF75% were mainly spherically shaped and did not present considerable differences from 60). the conventional Moreover, it emulsions, is possible E F to65% obse and rve E frF o70%, m the which sampcan les s be tai conﬁrmed ned with F by ITconfocal C that thlaser e oil scanning microscopy (Figure 2). It can be observed that the oil droplets of EF65% increased droplets were surrounded and coated with protein contained in the chickpea aquafaba considerably throughout the 60 days of storage. This was not evident in the droplet-size (CA). It is likely that both the protein and the starch, as well as all other bioactive mole- results (Table 1), but could be noted in the size distribution graph (Figure 1), in which the cules, leached out from the chickpea seed into the cooking water during the cooking pro- ﬁrst peak (lower droplet sizes) decreased in terms of relative volume (%) and the second cess that were responsible for enabling emulsification and providing stability to the sys- peak (higher droplet sizes) increased at longer storage days (i.e., days 45 and 60). tem, thereby preventing coalescence. Figure 2. Optical and fluorescence microscopic images of EΦ65%, EΦ70%, and EΦ75% at days 0 and 60; of Figure 2. Optical and ﬂuorescence microscopic images of E , E , and E at days 0 and 60; F65% F70% F75% storage at 25 °C (bar scale: 20 µm). Protein was dyed with FITC (green) and CO with Nile red. of storage at 25 C (bar scale: 20 m). Protein was dyed with FITC (green) and CO with Nile red. It has been frequently reported that HIPEs with small particle sizes possess relatively Moreover, it is possible to observe from the samples stained with FITC that the oil high stability; therefore this parameter is suitable and has been used as an index to evalu- droplets were surrounded and coated with protein contained in the chickpea aquafaba ate HIPE stability [25]. By taking this into account, it can be assumed that, as EΦ75% (CA). It is likely that both the protein and the starch, as well as all other bioactive molecules, leached out from the chickpea seed into the cooking water during the cooking process were responsible for enabling emulsiﬁcation and providing stability to the system, thereby preventing coalescence. It has been frequently reported that HIPEs with small particle sizes possess relatively high stability; therefore this parameter is suitable and has been used as an index to evaluate HIPE stability [25]. By taking this into account, it can be assumed that, as EF75% presented the smallest droplet size (conﬁrmed by D , D and the optical micrographs), it can [4,3] [3,2] be considered as the most stable system, followed by EF70% and EF65% in terms of size parameters. However, to further investigate the stability of these emulsions and HIPE, a combination of other parameters should be investigated. 3.3. Rheological Properties 3.3.1. Steady-Shear Behavior The ﬂow curve parameters (shear stress and shear rate) were ﬁtted to the power law model, and these are presented in Table 2. Foods 2022, 11, x FOR PEER REVIEW 8 of 15 Foods 2022, 11, x FOR PEER REVIEW 8 of 15 presented the smallest droplet size (confirmed by D [4,3], D [3,2] and the optical micro- presented the smallest droplet size (confirmed by D [4,3], D [3,2] and the optical micro- graphs), it can be considered as the most stable system, followed by EΦ70% and EΦ65% graphs), it can be considered as the most stable system, followed by EΦ70% and EΦ65% in terms of size parameters. However, to further investigate the stability of these emul- in terms of size parameters. However, to further investigate the stability of these emul- sions and HIPE, a combination of other parameters should be investigated. sions and HIPE, a combination of other parameters should be investigated. 3.3. Rheological Properties 3.3. Rheological Properties 3.3.1. Steady-Shear Behavior 3.3.1. Steady-Shear Behavior The flow curve parameters (shear stress and shear rate) were fitted to the power law The flow curve parameters (shear stress and shear rate) were fitted to the power law model, and these are presented in Table 2. model, and these are presented in Table 2. With respect to the variation in the modeled parameters (i.e., k and n) within the 60 With respect to the variation in the modeled parameters (i.e., k and n) within the 60 days of storage, there were significant differences (p < 0.05) among all the samples. The days of storage, there were significant differences (p < 0.05) among all the samples. The flow behavior index (n) values, which indicate the degree of non-Newtonian characteris- flow behavior index (n) values, which indicate the degree of non-Newtonian characteris- tics of the fluid, were between 0.31 and 0.50 (n < 1) for all the samples throughout storage, tics of the fluid, were between 0.31 and 0.50 (n < 1) for all the samples throughout storage, corresponding to a pseudoplastic behavior. At a higher oil concentration, the n values corresponding to a pseudoplastic behavior. At a higher oil concentration, the n values were lower, suggesting that the HIPE (EΦ75%) formed a more structured gel. The flow were lower, suggesting that the HIPE (EΦ75%) formed a more structured gel. The flow consistency index (k) is related to the apparent viscosity of the samples; the more viscous consistency index (k) is related to the apparent viscosity of the samples; the more viscous the sample, the higher the k. From our results, the k values were higher in the samples the sample, the higher the k. From our results, the k values were higher in the samples that contained more oil, which means that the HIPE (EΦ75%) was more structured and that contained more oil, which means that the HIPE (EΦ75%) was more structured and Foods 2022, 11, 1588 8 of 15 firmer than the emulsions (EΦ70% and EΦ65%), which can be confirmed by the apparent firmer than the emulsions (EΦ70% and EΦ65%), which can be confirmed by the apparent viscosity results at the shear rates of 5 and 300 per second (Table 2). These results can be viscosity results at the shear rates of 5 and 300 per second (Table 2). These results can be related to the droplet size of the samples, as the bigger the droplet size, the lower the related to the droplet size of the samples, as the bigger the droplet size, the lower the surface area available for droplets to interact, which, in turn, leads to lower shear thinning su Tr able face a 2. reFlow a avaiconsistency lable for drop index lets to(k) intand eractﬂow , whic behavior h, in turnindex , leads (tn o) lof owthe er sh power ear thilaw nninmodel g (R > 0.99), behavior and, consequently, lower viscosity [26,27]. behavior and, consequently, lower viscosity [26,27]. and apparent viscosity () at a shear rate of 5 ( ) and 300 s ( ) and the initial shear stress ( ) 5 300 0 Tab thr leoughout 2. Flow cothe nsist 60 enc days y inde of x (storage k) and float w 25 behaC. vior index (n) of the power law model (R >0.99), Table 2. Flow consistency index (k) and flow behavior index (n) of the power law model (R >0.99), −1 and apparent viscosity (η) at a shear rate of 5 (η5) and 300 s (η300) and the initial shear stress (σ0) −1 and apparent viscosity (η) at a shear rate of 5 (η5) and 300 s (η300) and the initial shear stress (σ0) throughout the 60 days of storage at 25 °C. Model Parameters (=kg ) Experimental Parameters throughout the 60 days of storage at 25 °C. Model Parame nters (σ = k * ) Experimental Parameters Storage (d) k (Pas ) n (Pas) (Pas) (Pa) 5 300 0 Model Parameters (σ = k * ) Experimental Parameters Storage (d) k (Pa.s ) n η5 (Pa.s) η300 (Pa.s) σ0 (Pa) Storage (d) k (Pa.s ) n η5 (Pa.s) η300 (Pa.s) σ0 (Pa) EF65% EΦ65% EΦ65% ab abc ab a a ab abc ab a a 0 0 4.75 4.75 ± 0.15 0.15 0.48 ± 0. 0.48 01 0.011.83 ± 0.03 1.83 0. 0.03 25 ± 0.00 0.256. 540.00 ± 0.26 6.54 0.26 ab abc ab a a 0 4.75 ± 0.15 0.48 ± 0.01 1.83 ± 0.03 0.25 ± 0.00 6.54 ± 0.26 a c ab ab a a c ab ab a 3 5.81 0.21 0.47 0.00 8.47 0.68 3 5.81 ± 0.21 0.47 ± 0.00 2.27 ± 0.15 2.27 0. 0.15 28 ± 0.01 0.288. 47 0.01 ± 0.68 a c ab ab a 3 5.81 ± 0.21 0.47 ± 0.00 2.27 ± 0.15 0.28 ± 0.01 8.47 ± 0.68 a ac b b a a ac b b a 7 5.84 0.52 0.47 0.01 2.34 0.27 0.29 0.02 8.50 0.96 7 5.84 ± 0.52 0.47 ± 0.01 2.34 ± 0.27 0.29 ± 0.02 8.50 ± 0.96 a ac b b a 7 5.84 ± 0.52 0.47 ± 0.01 2.34 ± 0.27 0.29 ± 0.02 8.50 ± 0.96 a ab abc ab a b ab abc ab a b a 14 5.19 0.62 0.48 0.01 2.14 0.25 0.27 0.01 7.86 0.92 14 5.19 ± 0.62 0.48 ± 0.01 2.14 ± 0.25 0.27 ± 0.01 7.86 ± 0.92 ab abc ab a b a 14 5.19 ± 0.62 ab 0.48 ± 0.01 2. ab 14 ± 0.25 0.27 ± b 0.01 7.86 ± 0. ab 92 a ab ab b ab a 30 4.75 0.60 0.49 0.01 1.94 0.22 0.26 0.01 7.03 1.15 30 4.75 ± 0.60 0.49 ± 0.01 1.94 ± 0.22 0.26 ± 0.01 7.03 ± 1.15 ab ab b ab a 30 4.75 ± 0.60 0.49 ± 0.01 1.94 ± 0.22 0.26 ± 0.01 7.03 ± 1.15 a ab ab ab ab ab ab ab ab a 45 4.80 0.24 0.49 0.00 1.95 0.15 0.27 0.01 7.17 0.73 45 4.80 ± 0.24 0.49 ± 0.00 1.95 ± 0.15 0.27 ± 0.01 7.17 ± 0.73 ab ab ab ab a 45 4.80 ± 0.24 b 0.49 ± 0.00 1. b95 ± 0.15 0.27 ± a 0.01 7.17 ± 0. ab 73 a 60 b b 1.80 a 0.06 ab a 6.41 0.28 4.40 0.04 0.50 0.00 0.26 0.00 60 4.40 ± 0.04 0.50 ± 0.00 1.80 ± 0.06 0.26 ± 0.00 6.41 ± 0.28 b b a ab a 60 4.40 ± 0.04 0.50 ± 0.00 1.80 ± 0.06 0.26 ± 0.00 6.41 ± 0.28 EΦ70% EF70% EΦ70% a ab a a a 0 10.86 ± 0.65 0.41 ± 0.00 4.02 ± 0.24 0.37 ± 0.02 16.47 ± 1.17 a ab a a a a ab a a a 0 10.86 0.65 4.02 0.24 0.37 0.02 16.47 1.17 0 10.86 ± 0.65 0.41 ± 0.41 0.00 0.00 4.02 ± 0.24 0.37 ± 0.02 16.47 ± 1.17 cd ac a b bc 3 13.12 ± 0.26 0.40 ± 0.00 4.82 ± 0.36 0.43 ± 0.02 20.25 ± 1.04 cd ac a b bc cd ac a b bc 3 13.12 0.26 0.40 0.00 4.82 0.36 0.43 0.02 20.25 1.04 3 13.12 ± 0.26 0.40 ± 0.00 4.82 ± 0.36 0.43 ± 0.02 20.25 ± 1.04 d c a b c 7 13.49 ± 0.44 0.39 ± 0.00 4.83 ± 0.43 0.43 ± 0.02 20.44 ± 1.00 c a c d b d c a b c 7 13.49 0.44 0.39 0.00 4.83 0.43 0.43 0.02 20.44 1.00 7 13.49 ± 0.44 0.39 ± 0.00 4.83 ± 0.43 0.43 ± 0.02 20.44 ± 1.00 abcd abc a ab abc 14 11.95 ± 0.66 0.40 ± 0.00 4.47 ± 0.39 0.40 ± 0.01 18.55 ± 1.58 abcd abc a ab abc 14 abcd abc 4.47 a 0.39 ab abc 11.95 0.66 0.40 0.00 0.40 0.01 18.55 1.58 14 11.95 ± 0.66 0.40 ± 0.00 4.47 ± 0.39 0.40 ± 0.01 18.55 ± 1.58 ab b a ab ab 30 10.94 ± 0.71 0.41 ± 0.00 4.13 ± 0.31 0.39 ± 0.02 16.65 ± 1.47 ab b a ab ab 30 10.94 a0.71 b 0.41 b 0.00 4.13 a 0.31 ab0.39 0.02 ab 16.65 1.47 30 10.94 ± 0.71 0.41 ± 0.00 4.13 ± 0.31 0.39 ± 0.02 16.65 ± 1.47 bcd abc a b abc 45 12.63 ± 1.00 0.41 ± 0.00 4.62 ± 0.49 0.43 ± 0.02 18.59 ± 2.06 bcd abc a b abc 45 4.62 0.49 12.63 b1.00 cd 0.41 abc0.00 a b 0.43 0.02 abc 18.59 2.06 Foods 2022, 11, x FOR 45 PE ER REVIEW 12. 63 ± 1.00 0.41 ± 0.00 4.62 ± 0.49 0.43 ± 0.02 18.59 ± 2.06 9 of 15 abc ab a ab ab 60 11.74 ± 0.24 0.41 ± 0.01 4.16 ± 0.21 0.41 ± 0.01 16.67 ± 0.48 abc ab a ab ab 60 11.74 a0.24 bc 0.41 ab 0.01 4.16 a 0.21 ab0.41 0.01 ab 16.67 0.48 60 11.74 ± 0.24 0.41 ± 0.01 4.16 ± 0.21 0.41 ± 0.01 16.67 ± 0.48 EΦ75% EΦ75% a abc a a a EF75% 0 26.69 ± 2.93 0.32 ± 0.01 8.96 ± 0.86 0.55 ± 0.06 40.67 ± 4.33 a abc a a a 0 26.69 ± 2.93 0.32 ± 0.01 8.96 ± 0.86 0.55 ± 0.06 40.67 ± 4.33 ab a a ab ab 3 33.93 ± 3.09 a 0.31 ± 0.00 11. abc 31 ± 1.30 0.65 ± a0.07 50.55 ± 5.73 a a 0 26.69 2.93 ab 0.32 0.01 bc 8.96 0.86 a 0.55 0.06 ab 40.67 4.33 ab 45 31.02 ± 1.92 0.32 ± 0.00 10.37 ± 0.61 0.66 ± 0.02 44.55 ± 2.67 ab a a ab ab 3 33.93 ± 3.09 0.31 ± 0.00 11.31 ± 1.30 0.65 ± 0.07 50.55 ± 5.73 ab abc a ab ab a a 7 31.28 ± 3.19 ab 0.31 ± 0.01 10.07 ± 1.20 0.63 ± 0.03 46.28 ± 4.ab 77 ab 3 33.93 3.09 0.31 0.00 11.31 1.30 0.65 0.07 50.55 5.73 ab abc a ab ab 7 31.28 ± 3.19 0.31 ± 0.01 10.07 ± 1.20 0.63 ± 0.03 46.28 ± 4.77 b ab a b b ab abc a ab ab 14 35.74 ± 3.98 0.31 ± 0.01 11.27 ± 1.22 0.69 ± 0.04 53.37 ± 5.72 7 10.07 1.20 31.28 3.19 0.31 0.01 0.63 0.03 46.28 4.77 b ab a b b 14 35.74 ± 3.98 0.31 ± 0.01 11.27 ± 1.22 0.69 ± 0.04 53.37 ± 5.72 ab abc a ab ab b ab a b b 30 28.54 ± 1.10 0.32 ± 0.01 9.42 ± 0.23 0.61 ± 0.04 42.90 ± 1.20 14 35.74 3.98 0.31 0.01 11.27 1.22 0.69 0.04 53.37 5.72 ab abc a ab ab 30 28.54 ± 1.10 ab0.32 ± 0.01 9.42 c ± 0.23 0.61 ± 0.0 a4 42.90 ± 1.20 ab ab 60 30.45 ± 1.41 ab 0.33 ± 0. abc 01 9.88 ± 0.51 0.66 ± 0.0 ab 1 42.45 ± 2.22 ab 30 9.42 0.23 28.54 1.10 0.32 0.01 0.61 0.04 42.90 1.20 ab bc a ab ab 45 31.02 1.92 0.32 0.00 10.37 0.61 0.66 0.02 44.55 2.67 c a ab ab ab 60 30.45 1.41 0.33 0.01 9.88 0.51 0.66 0.01 42.45 2.22 n n is σ shear is she str ar ess stre (Pa); ss (P kais ); k ﬂow is fl consistency ow consistindex ency i(Pa ndes) x (;P a·is s)shear ; γ is rate shear (1/s); rateand (1/sn ); is an ﬂow d n ibehavior s flow be inde havxior (dimensionless). Mean values (mean value standard derivation, n = 3) for the same parameter, sample, and index (dimensionless). Mean values (mean value ± standard derivation, n = 3) for the same param- column with different lower-case superscripts are signiﬁcantly different based on Tukey’s test at p < 0.05. eter, sample, and column with different lower-case superscripts are significantly different based on Tukey’s test at p < 0.05. With respect to the variation in the modeled parameters (i.e., k and n) within the 60 days of storage, there were signiﬁcant differences (p < 0.05) among all the samples. The Viscosity is an important parameter to evaluate, as it describes the flow properties of ﬂow behavior index (n) values, which indicate the degree of non-Newtonian characteristics a system and can directly affect the appearance and the consistency of a product. It is of the ﬂuid, were between 0.31 and 0.50 (n < 1) for all the samples throughout storage, directly dependent on strain rate; therefore, it is determined in terms of apparent viscosity corresponding to a pseudoplastic behavior. At a higher oil −1 concentration, −1 the n values and was expressed in this study at the shear rates of 300 s and 5 s (Table 2). Both emul- were lower, suggesting that the HIPE (EF75%) formed a more structured gel. The ﬂow sions and the HIPE showed shear-thinning behavior, which is characteristic of non-New- consistency index (k) is related to the apparent viscosity of the samples; the more viscous tonian fluids whose viscosity decreases under increasing shear rates. Moreover, at higher the sample, the higher the k. From our results, the k values were higher in the samples that oil concentrations (EΦ75% > EΦ70% > EΦ65%) the shear stress was higher, resulting in contained more oil, which means that the HIPE (EF75%) was more structured and ﬁrmer increased viscosity, a parameter that can be a valuable feature depending on the desired than the emulsions (EF70% and EF65%), which can be conﬁrmed by the apparent viscosity application. With respect to the variation in the apparent viscosity both at the shear rates results at − the 1 shear −1rates of 5 and 300 per second (Table 2). These results can be related to of 300 s and 5 s within the 60 days of storage, there was a significant difference (p < 0.05) the droplet size of the samples, as the bigger the droplet size, the lower the surface area −1 for all samples except for EΦ75% (at a shear rate of 5 s ). available for droplets to interact, which, in turn, leads to lower shear thinning behavior All the samples presented an initial shear stress (σ0) throughout storage (Table 2). and, consequently, lower viscosity [26,27]. With respect to the variation in the initial shear stress within 60 days of storage, there was Viscosity is an important parameter to evaluate, as it describes the ﬂow properties a significant difference (p < 0.05) for all samples except for EΦ65%. The presence of σ0 of a system and can directly affect the appearance and the consistency of a product. It is indicates that the system needs an initial force to be applied for the sample to begin flow- directly dependent on strain rate; therefore, it is determined in terms of apparent viscosity ing. In turn, σ0 values are directly related to sample fluidity. Fluidity is defined as the 1 1 and was expressed in this study at the shear rates of 300 s and 5 s (Table 2). Both ability of the sample to retain its appearance and structural integrity when inverted. In emulsions and the HIPE showed shear-thinning behavior, which is characteristic of non- that sense, the higher the σ0, the higher the ability of the system to retain its appearance, Newtonian ﬂuids whose viscosity decreases under increasing shear rates. Moreover, at which was confirmed by photographs taken directly after the samples were inverted (Ta- ble 2). As can be observed, both EΦ70% and EΦ75% presented higher σ0 and consequently lower mobility, when compared to EΦ65% at day 0 (Figure 3a) as well as throughout all the storage days. Higher fluidity indicates that molecules are less viscous and packed to- gether to a lesser extent, which can be confirmed by the apparent viscosity results (Table 2) and the optical and fluorescence microscopic images (Figure 2). In summary, as EΦ75% is more viscous, and presented higher k values and lower n values, it can be considered as the most stable system, followed by EΦ70% and EΦ65%. Figure 3. Flow curves plotted as shear stress versus shear rate (a), stress sweeps (b), and frequency (c) tests of EΦ65%, EΦ70%, and EΦ75% at day 0 of storage at 25 °C. 3.3.2. Oscillatory Shear Behavior Amplitude Sweep Foods 2022, 11, x FOR PEER REVIEW 9 of 15 ab bc a ab ab 45 31.02 ± 1.92 0.32 ± 0.00 10.37 ± 0.61 0.66 ± 0.02 44.55 ± 2.67 ab c a ab ab 60 30.45 ± 1.41 0.33 ± 0.01 9.88 ± 0.51 0.66 ± 0.01 42.45 ± 2.22 σ is shear stress (Pa); k is flow consistency index (Pa·s) ; γ is shear rate (1/s); and n is flow behavior index (dimensionless). Mean values (mean value ± standard derivation, n = 3) for the same param- eter, sample, and column with different lower-case superscripts are significantly different based on Tukey’s test at p < 0.05. Viscosity is an important parameter to evaluate, as it describes the flow properties of a system and can directly affect the appearance and the consistency of a product. It is directly dependent on strain rate; therefore, it is determined in terms of apparent viscosity −1 −1 and was expressed in this study at the shear rates of 300 s and 5 s (Table 2). Both emul- Foods 2022, 11, 1588 9 of 15 sions and the HIPE showed shear-thinning behavior, which is characteristic of non-New- tonian fluids whose viscosity decreases under increasing shear rates. Moreover, at higher oil concentrations (EΦ75% > EΦ70% > EΦ65%) the shear stress was higher, resulting in higher oil concentrations (EF75% > EF70% > EF65%) the shear stress was higher, resulting increased viscosity, a parameter that can be a valuable feature depending on the desired in increased viscosity, a parameter that can be a valuable feature depending on the desired application. With respect to the variation in the apparent viscosity both at the shear rates application. With respect to the variation in the apparent viscosity both at the shear rates of −1 −1 1 1 of 300 s and 5 s within the 60 days of storage, there was a significant difference (p < 0.05) 300 s and 5 s within the 60 days of storage, there was a signiﬁcant difference (p < 0.05) −1 for all samples except for EΦ75% (at a shear rate of 5 s ). for all samples except for EF75% (at a shear rate of 5 s ). All the samples presented an initial shear stress (σ0) throughout storage (Table 2). All the samples presented an initial shear stress ( ) throughout storage (Table 2). With respect to the variation in the initial shear stress within 60 days of storage, there was With respect to the variation in the initial shear stress within 60 days of storage, there was a significant difference (p < 0.05) for all samples except for EΦ65%. The presence of σ0 a signiﬁcant difference (p < 0.05) for all samples except for EF65%. The presence of indicates that the system needs an initial force to be applied for the sample to begin flow- indicates that the system needs an initial force to be applied for the sample to begin ﬂowing. ing. In turn, σ0 values are directly related to sample fluidity. Fluidity is defined as the In turn, values are directly related to sample ﬂuidity. Fluidity is deﬁned as the ability of ability of the sample to retain its appearance and structural integrity when inverted. In the sample to retain its appearance and structural integrity when inverted. In that sense, that sense, the higher the σ0, the higher the ability of the system to retain its appearance, the higher the , the higher the ability of the system to retain its appearance, which was wh conﬁrmed ich was c by onphotographs firmed by pho taken tograp dir hsectly taken after direthe ctly samples after the wer samepinverted les were i(T nv able erted 2). (TAs a- ble 2). As can be observed, both EΦ70% and EΦ75% presented higher σ0 and consequently can be observed, both EF70% and EF75% presented higher and consequently lower lmobility ower mo , b when ility, wh compar en coed mpto are E dF t65% o EΦat 65% day at 0 day (Figur 0 (Fe ig3 u a) re as 3a) well as we asllthr asoughout througho all ut the all tstorage he storag days. e day Higher s. High ﬂu eridity fluid indicates ity indica that tes tmolecules hat molecu ar le esless are viscous less viscand ous packed and pac tk ogether ed to- to a lesser extent, which can be conﬁrmed by the apparent viscosity results (Table 2) and gether to a lesser extent, which can be confirmed by the apparent viscosity results (Table the optical and ﬂuorescence microscopic images (Figure 2). In summary, as EF75% is more 2) and the optical and fluorescence microscopic images (Figure 2). In summary, as EΦ75% viscous, and presented higher k values and lower n values, it can be considered as the most is more viscous, and presented higher k values and lower n values, it can be considered stable system, followed by EF70% and EF65%. as the most stable system, followed by EΦ70% and EΦ65%. Figure 3. Flow curves plotted as shear stress versus shear rate (a), stress sweeps (b), and frequency Figure 3. Flow curves plotted as shear stress versus shear rate (a), stress sweeps (b), and frequency ((c c)) ttests ests o of f E EΦF6 65%, 5%, E EΦF 70 70%, %, an and d E E ΦF 775% 5% atat day day 0 0 ofof ststorage orage atat 25 25 °CC. . 3.3.2. Oscillatory Shear Behavior 3.3.2. Oscillatory Shear Behavior Amplitude Sweep Amplitude Sweep An amplitude sweep test was conducted by varying the oscillatory stress (0.01–100 Pa) at a ﬁxed frequency (1 Hz). This determined the linear viscoelastic region (LVR), in which G (storage modulus) and G” (viscous modulus) were almost constant, and the nonlinear region, in which G and G” started to decrease [28]. The oscillatory stress value, at which G sharply decreased, is deﬁned as the critical oscillatory stress, also known as the limiting value of oscillatory stress (OS ). On day 0 (Figure 3b), at low-stress values (0.01–1 Pa), the G value of EF75% was the highest (~1250 Pa), showing higher elastic behavior when compared to EF70% and EF65%, which presented G of ~700 Pa and 380 Pa, respectively. When the stress was increased (>1 Pa), it was possible to identify the OS values, which were 1, 5, and 20 for EF65%, EF70%, and EF75%, respectively. Determining the OS value is important as it determines the maximum deformation that a system can withstand without structural breakdown [28]. Results of this study show that EF65% (lower OS ) is the ﬁrst to lose structure, followed by EF70% and EF75%. This outcome indicates that an increase in the oil concentration improves the strength and rigidity of the system. To evaluate if the samples maintained their initial structure throughout the 60 days of storage, further rheological parameters at the LVR were determined from the amplitude sweep measurements (Table 3). Foods 2022, 11, 1588 10 of 15 Table 3. Rheological parameters of storage (G ) and loss (G” ) moduli at the linear viscoelastic LVR LVR region (LVR), limiting value of oscillatory stress (OS ), the loss-tangent (tan ) at the LVR, ﬂow- L LVR point oscillatory stress (FP ), and ﬂow-point G (FP ) as determined by stress sweep tests (at a 1 Hz OS G frequency) for samples stored at 25 C. Sample Storage (d) G” (Pa) OS (Pa) tan FP (Pa) FP (Pa) G (Pa) LVR LVR L LVR OS G ac a a a ab cd 0 380.94 37.04 1.26 0.00 0.15 0.00 105.27 34.63 58.70 5.42 2.64 0.34 a a a e a bc 3 426.55 43.31 1.26 0.00 0.17 0.02 4.03 0.65 74.56 21.71 72.01 7.90 a bc a a d a 452.70 8.89 72.63 1.66 1.26 0.00 0.16 0.00 2.84 0.00 107.11 28.33 ac c e a ab bcd EF65% 14 415.05 50.79 81.13 7.37 1.00 0.00 115.47 26.41 0.20 0.02 2.45 0.34 bc ab d ab ab 30 79.37 35.80 318.57 47.74 59.10 10.2 0.74 0.09 0.19 0.02 1.61 0.26 b a c b a a 45 53.62 1.02 0.63 0.00 1.32 0.17 81.25 8.28 243.02 34.13 0.22 0.03 a a b b b abc 60 47.46 5.58 58.21 5.13 215.58 30.05 0.50 0.00 0.22 0.01 1.79 0.00 a b e a bc ab 0 695.53 39.37 5.01 0.00 0.11 0.00 76.11 3.66 10.52 1.34 181.60 17.44 a e c a ab ab 3 742.63 27.58 5.01 0.00 12.27 1.69 147.08 7.24 84.90 2.52 0.11 0.00 a a d bc abc ab 7 753.74 50.41 97.10 12.31 3.98 0.00 0.13 0.01 8.36 1.07 203.23 12.49 a a cd cd ab b EF70% 14 764.28 42.70 99.46 4.70 3.71 0.47 0.13 0.00 6.56 2.74 227.96 34.67 ab bc abc ab b 30 749.47 26.23 91.81 3.21 3.16 0.00 0.12 0.00 7.13 0.00 241.78 43.84 a a ab d a ab 45 661.30 38.73 95.45 5.11 5.49 0.92 2.73 0.38 0.14 0.00 205.81 29.12 a e a a b ab 60 2.03 0.46 0.17 0.01 5.27 0.67 144.58 13.76 532.30 38.38 89.48 4.75 c a d a b a 0 1377.74 69.46 120.09 25.22 0.10 0.01 318.96 39.47 19.95 0.00 65.56 27.44 a a c a ab ab 3 1142.70 21.02 114.06 2.20 15.85 0.00 0.10 0.00 41.88 5.34 241.61 44.11 a a a a b ab 7 1087.21 27.81 103.38 6.76 12.59 0.00 0.09 0.01 34.35 2.36 257.43 17.40 a a a b ab ab EF75% 14 1190.30 71.31 117.95 10.63 0.10 0.00 12.59 0.00 35.72 0.00 279.65 54.68 a a a a ab b 30 1073.52 37.48 101.29 4.07 7.94 0.00 0.09 0.00 41.88 5.34 170.20 13.41 a a a a a a 45 1157.35 68.12 114.39 1.69 7.94 0.00 0.10 0.00 25.45 2.92 293.23 61.55 a a a a b ab 60 928.37 41.38 105.39 6.47 7.40 0.94 0.11 0.01 20.99 2.68 247.10 44.41 Flow point (G = G”). Mean values (mean value standard derivation, n = 3) for the same parameter, sample, and column with different lower-case superscripts are signiﬁcantly different based on Tukey’s test at p < 0.05. The results show that, for all three formulations, the OS decreases considerably, indicating that samples lose their structure at lower oscillatory stress levels. The values of G and G” at the LVR also decreased with increased storage. The magnitude of the viscoelastic moduli for G was in accordance with the previously reported values for LVR some other food hydrocolloids [27]. As for the loss-tangent values (tan ), which is LVR the ratio between G and G” , all values were in the range of 0.09–0.22, indicating a LVR LVR predominantly elastic behavior. Moreover, the ﬂow point (G = G”) indicates the stress at which the ﬁrst non-linear structural change occurs. In this study, the HIPE (EF75%) had higher oscillatory stress values at the ﬂow point (21–66 Pa) compared to emulsions EF70% (5–11 Pa) and EF65% (1–4 Pa), indicating that it undergoes structural changes at higher stress values. In summary, the results of the amplitude sweep test determined the structural strength and allowed us to distinguish between weaker and stronger gels. EF75% was the strongest gel throughout storage as it remained in the LVE region (higher OS ) for a longer period of time, and it presented higher G (Pa), G” (Pa), FP (Pa), and FP (Pa). The results LVR LVR OS G also demonstrate that, with the increase in storage days, the strength of the entire system decreased. Nonetheless, it can be assumed that EF75% is the most stable system, as it is the strongest gel, followed by EF70% and EF65%. Frequency Sweep To further investigate the viscous and elastic behavior changes under increased fre- quency applications, a frequency sweep analysis at 0.1 Pa (within the LVR for all samples and days) was conducted (Figure 3c). Throughout the 60 days of storage for all samples, no 0 0 crossover point (G = G”) was detected and G was always higher than G” (data not shown). These results indicate that, within the tested experimental range (0.01–10 Hz), all samples displayed gel-like behavior—more similar to a solid rather than a liquid. Therefore, the deformations can be considered as essentially elastic and recoverable [28]. Moreover, the results suggest that, even at higher frequencies, the rheological responses of both emulsion Foods 2022, 11, 1588 11 of 15 and the HIPE have no obvious effect by the applied deformation rate. This behavior was also observed in other studies in the literature [25,28]. At a ﬁxed frequency of 1 Hz, the tan values of EF75%, EF70%, and EF65% were within the ranges of 0.08–0.14, 0.12–0.18, and 0.16–0.22, respectively, indicating that all the samples were more elastic than viscous throughout the 60 days of storage (Table 4). In addition, it can be noted that the EF75% had the lowest values of tan, indicating that it has a stronger gel structure, which is in accordance with the apparent viscosity and amplitude sweep tests. 0 0 0 Table 4. Power law parameters (k and n ) for the storage modulus G throughout the 60 days of storage at 25 C and the storage (G ) and loss (G” ) moduli; the loss-tangent (tan) at a frequency LVR of 1 Hz for samples stored at 25 C. ’ ’ n Model Parameters (G =k w ) Experimental Parameters 0 n 0 2 0 Samples Storage (d) k (Pas ) n R G (Pa) G” (Pa) tan a a a ab abc 0 0.18 0.02 0.96 599 54 0.18 0.01 394 32 109 12 abc a a c a 3 461 4 0.22 0.05 0.97 718 11 134 8 0.19 0.01 c a a a bc 7 489 27 0.18 0.03 0.96 723 53 119 6 0.16 0.00 bc a a c a EF65% 14 0.19 0.02 0.97 654 89 130 13 0.20 0.04 487 30 a a ab ab a 30 367 46 0.17 0.01 0.96 546 55 96 11 0.18 0.02 d a b ab a 45 0.19 0.02 0.96 0.22 0.05 273 36 425 36 92 14 d a b a a 60 266 31 0.19 0.02 0.96 408 49 79 13 0.19 0.03 ab ab a a ab 0 0.98 1097 42 172 12 846 58 0.14 0.02 0.16 0.01 b b c b b 3 914 20 0.17 0.01 0.99 1396 163 250 40 0.18 0.03 ab ab ab ab 7 810 56 0.13 0.02 0.95 1069 37 145 27 0.14 0.02 ab ab a a ab EF70% 14 828 53 0.14 0.02 0.97 1105 109 174 36 0.16 0.02 ac a a a ab 30 731 40 0.12 0.00 0.96 972 43 115 6 0.12 0.01 a ac ab ab a ab 45 709 71 0.97 151 18 0.14 0.01 968 79 0.16 0.01 c ab b a ab 60 617 22 0.15 0.01 0.97 845 38 130 8 0.15 0.00 a a a a ab 0 1252 97 0.07 0.01 0.97 1357 51 120 29 0.09 0.02 a a ab a a 3 1244 18 0.08 0.00 0.91 1447 17 122 5 0.08 0.00 ab ab ab abc 7 1207 98 0.96 0.09 0.02 1419 80 165 36 0.12 0.03 a ab ab ab abc EF75% 14 1326 43 0.09 0.00 0.96 1502 162 182 46 0.12 0.02 a a a a abc 30 1128 82 0.08 0.01 0.97 1342 87 124 19 0.09 0.01 a b b b bc 45 1183 26 0.98 0.11 0.01 1698 224 226 19 0.13 0.01 a b ab ab c 60 1122 76 0.11 0.01 0.96 1375 89 187 28 0.14 0.01 Mean values (mean value standard derivation, n = 3) for the same parameter, sample, and column with different lower-case superscripts are signiﬁcantly different based on Tukey’s test at p < 0.05. To further investigate the frequency dependency of G values, a power law relation was applied [28,29] and the degree of frequency dependence was determined by power law parameters (Table 4). 0 0 Low n values are characteristic of elastic gels, n values near to 1 indicate that the 0 0 system behaves as a viscous gel, and at n values close to zero, the G value does not change with the frequency [28]. As can be observed in Table 4, EF75% had the lowest values of n , presenting values very close to 0. These results conﬁrm that EF75% has the least dependency on frequency changes, which can be visualized in Figure 3c, where at any given frequency G plot for EF75% barely has a slope, indicating there are minimal changes 0 0 in the G value. The highest k values were also found to be from the EF75% sample, which means that these samples had stronger elastic structures than the others. This value also decreased with the increase in storage days for all samples (except for EF75%), which can be attributed to the formation of a weaker network. Foods 2022, 11, 1588 12 of 15 Temperature Sweep To determine the sensitivity of the sample structure to thermal changes, a temperature sweep was conducted. All samples had predominance of elastic behavior over the viscous (G > G”) and formed structured gels with different strengths. No melting was detected as G did not equal G” in the entire temperature range evaluated, indicating that all samples remained in a solid-like state. From 10 C to around 40 C, all samples showed a slight G and G” decrease. However, at temperatures above 40 C, an increase in G and G” values was observed for both emulsions (EF65% and EF70%), behavior which was observed only slightly in the HIPE (EF75%) (Figure 4). This increase in G can be related to the development and transformation of the liquid state into a gel state (sol–gel transition) and/or due to the thickening effect of the starches leached out from the chickpea seed, which restricts the mobility of ﬂuids. [28]. Similar results were obtained in other studies Foods 2022, 11, x FOR PEER REVIEW 13 of 15 using protein, such as with whey protein emulsions [30] and emulsion gels stabilized by pea ﬂour [31]. Figure 4. Temperature sweeps (heating) for EΦ65%, EΦ70%, and EΦ75% throughout 60 days storage Figure 4. Temperature sweeps (heating) for EF65%, EF70%, and EF75% throughout 60 days storage at 25 °C. at 25 C. 3.4. Conventional Emulsions and HIPE Stability Within the days of storage, it was possible to observe that, for EF65%, already after day 0, G started to considerably increase, followed by a sharp decrease (Figure 4). Following Following centrifugation, all the samples were separated into three layers as was re- day 14, G even became higher than EF70%. This behavior was not observed in EF70% ported in previous studies with protein HIPEs [16,33,34]. The top layer consisted of the oil and EF75%, which remained with similar behaviors in every temperature scan throughout fraction and was quantified in terms of oil loss upon centrifugation (Figure 5a). The mid- the 60 days of storage. dle layer consisted of a cream layer and the bottom layer was an aqueous phase. Up to The structure of the studied emulsions and HIPE was evaluated through a correlation storage day 14, the oil loss was higher at the higher oil concentration (EΦ75% > EΦ70% > 0 0 0 between G and G” (G /G). At a G /G” ratio lower than 10, the gel is considered a weak EΦ65%). These results may be related to structuring agent concentration, as there was gel; whereas, if this value is above 10, the gel is considered a strong gel [32]. At the probably not enough structurant available to be adsorbed on the surface of oil droplets at maximum temperature of analysis (80 C), the calculation for the gel strength of these higher oil concentrations. Interestingly, after 14 d of storage, the oil loss was considerably systems was performed. The ratios were 7.5, 5.8, and 4.6, for EF75%, EF70%, and EF65%, reduced, indicating that a rearrangement might have occurred. Although the oil loss upon respectively, on day 0, indicating that the gel strength of the samples increased at higher centrifugation showed a significant difference (p < 0.05) by the Tukey’s test, the variation concentrations of oil. In summary, a higher F concentration increased the apparent viscosity between days 0 and 30 did not exceed 1.5, 0.3, and 0.2% for EΦ75%, EΦ70%, and EΦ65%, and viscoelasticity of both emulsions and the HIPE. respectively, which can be considered quite low. Figure 5. Oil loss upon centrifugation throughout 60 days of storage at 25 °C (a) and appearance of samples after centrifugation (b). Mean values (mean value ± standard derivation, n = 3) for the same parameter, sample, and column with different lower-case superscripts are significantly different based on Tukey’s test at p < 0.05. 4. Conclusions Foods 2022, 11, x FOR PEER REVIEW 13 of 15 Foods 2022, 11, 1588 13 of 15 Figure 4. Temperature sweeps (heating) for EΦ65%, EΦ70%, and EΦ75% throughout 60 days storage at 25 °C. 3.4. Conventional Emulsions and HIPE Stability 3.4. Conventional Emulsions and HIPE Stability Following centrifugation, all the samples were separated into three layers as was re- Following centrifugation, all the samples were separated into three layers as was re- ported in previous studies with protein HIPEs [16,33,34]. The top layer consisted of the oil ported in previous studies with protein HIPEs [16,33,34]. The top layer consisted of the oil fraction and was quantified in terms of oil loss upon centrifugation (Figure 5a). The mid- fraction and was quantiﬁed in terms of oil loss upon centrifugation (Figure 5a). The middle dle layer consisted of a cream layer and the bottom layer was an aqueous phase. Up to layer consisted of a cream layer and the bottom layer was an aqueous phase. Up to storage day storag 14,ethe day oil 14 loss , the was oil l higher oss waat s h the ighhigher er at th oil e h concentration igher oil conc(E enF tr75% ation> (E EΦF75% 70% > > E EΦF7 65%) 0% > . These EΦ65% results ). Thesmay e resbe ults r elated may bto e rstr ela ucturing ted to str agent ucturiconcentration, ng agent conce as ntr ther atioe n,was as tpr heobably re was not enough structurant available to be adsorbed on the surface of oil droplets at higher probably not enough structurant available to be adsorbed on the surface of oil droplets at oil concentrations. Interestingly, after 14 d of storage, the oil loss was considerably re- higher oil concentrations. Interestingly, after 14 d of storage, the oil loss was considerably duced, indicating that a rearrangement might have occurred. Although the oil loss upon reduced, indicating that a rearrangement might have occurred. Although the oil loss upon centrifugation showed a signiﬁcant difference (p < 0.05) by the Tukey’s test, the variation centrifugation showed a significant difference (p < 0.05) by the Tukey’s test, the variation between days 0 and 30 did not exceed 1.5, 0.3, and 0.2% for EF75%, EF70%, and EF65%, between days 0 and 30 did not exceed 1.5, 0.3, and 0.2% for EΦ75%, EΦ70%, and EΦ65%, respectively, which can be considered quite low. respectively, which can be considered quite low. Figure 5. Oil loss upon centrifugation throughout 60 days of storage at 25 °C (a) and appearance of Figure 5. Oil loss upon centrifugation throughout 60 days of storage at 25 C (a) and appearance samples after centrifugation (b). Mean values (mean value ± standard derivation, n = 3) for the same of samples after centrifugation (b). Mean values (mean value standard derivation, n = 3) for the parameter, sample, and column with different lower-case superscripts are significantly different same parameter, sample, and column with different lower-case superscripts are signiﬁcantly different based on Tukey’s test at p < 0.05. based on Tukey’s test at p < 0.05. 4. Conclusions 4. Conclusions In this study, solely chickpea aquafaba at different oil phase volumes (F) of canola oil were used to produce stable emulsions and HIPE. The results indicate that the emulsions resist prolonged storage without breakdown through physical instability mechanisms. In terms of the rheological properties, all samples showed gel-like behavior throughout 60 days of storage at 25 C. Moreover, the rheological tests showed a weakening of the gel’s strength throughout storage. Among the three studied formulations, EF75% showed to be the most stable system in terms of droplet size and rheological properties. In addition, samples had less than 1.5% of oil loss after centrifugation, which indicated that all samples had very good centrifugation stability. The outcome of this study produced an inexpensive potential substitute for saturated and trans-fat for food products, in addition to the valuable utilization of biowaste from the food industry and its conversion into a high value food ingredient. Moreover, the CA-based emulsions and HIPE did not require any modiﬁcation method prior to production (i.e., sonication) nor further cumbersome processes (i.e., gelling, complexing, and heating) or the use of expensive equipment, and thus no high additional operational costs. Nonetheless, to study the feasibility and acceptability of using these systems as a fat replacer, there is a need for application in a food system, as well as consumer sensory analysis. Author Contributions: Conceptualization, G.G.B.K.; methodology, G.G.B.K.; formal analysis, G.G.B.K. and A.M.M.T.G.; investigation, G.G.B.K.; resources, G.G.B.K. and M.D.H.; writing—original draft preparation, G.G.B.K.; writing—review and editing, G.G.B.K. and M.D.H.; visualization, G.G.B.K.; project administration, G.G.B.K.; funding acquisition, G.G.B.K. and M.D.H. All authors have read and agreed to the published version of the manuscript. Foods 2022, 11, 1588 14 of 15 Funding: The authors are grateful to São Paulo Research Foundation (FAPESP, grant #2020/05074-6, #2021/06863-7 and #2019/27354-3) and to the National Council for Scientiﬁc and Technological Development (CNPq, grant #428644/2018-0 and #309022/2021-5) for project ﬁnancial support. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: The data used in this study are available in this article. Acknowledgments: The authors acknowledge the kind donation of chickpea BRS Aleppo by EM- BRAPA Vegetables. Conﬂicts of Interest: The authors declare no conﬂict of interest. References 1. He, Y.; Purdy, S.K.; Tse, T.J.; Taran, B.; Meda, V.; Reaney, M.J.T.; Mustafa, R. Standardization of Aquafaba Production and Application in Vegan Mayonnaise Analogs. Foods 2021, 10, 1978. [CrossRef] [PubMed] 2. He, Y.; Shim, Y.Y.; Shen, J.; Kim, J.H.; Cho, J.Y.; Hong, W.S.; Meda, V.; Reaney, M.J.T. Aquafaba from Korean Soybean II: Physicochemical Properties and Composition Characterized by NMR Analysis. Foods 2021, 10, 2589. [CrossRef] [PubMed] 3. Damian, J.J.; Huo, S.; Serventi, L. Phytochemical Content and Emulsifying Ability of Pulses Cooking Water. Eur. Food Res. Technol. 2018, 244, 1647–1655. [CrossRef] 4. Stantiall, S.E.; Dale, K.J.; Calizo, F.S.; Serventi, L. Application of Pulses Cooking Water as Functional Ingredients: The Foaming and Gelling Abilities. Eur. Food Res. Technol. 2018, 244, 97–104. [CrossRef] 5. Shim, Y.Y.; He, Y.; Kim, J.H.; Cho, J.Y.; Meda, V.; Hong, W.S.; Shin, W.-S.; Kang, S.J.; Reaney, M.J.T. Aquafaba from Korean Soybean I: A Functional Vegan Food Additive. Foods 2021, 10, 2433. [CrossRef] 6. He, Y.; Shim, Y.Y.; Mustafa, R.; Meda, V.; Reaney, M.J.T. Chickpea Cultivar Selection to Produce Aquafaba with Superior Emulsion Properties. Foods 2019, 8, 685. [CrossRef] 7. He, Y.; Meda, V.; Reaney, M.J.T.; Mustafa, R. Aquafaba, a New Plant-Based Rheological Additive for Food Applications. Trends Food Sci. Technol. 2021, 111, 27–42. [CrossRef] 8. Alsalman, F.B.; Ramaswamy, H.S. Evaluation of Changes in Protein Quality of High-Pressure Treated Aqueous Aquafaba. Molecules 2021, 26, 234. [CrossRef] 9. Alsalman, F.B.; Tulbek, M.; Nickerson, M.; Ramaswamy, H.S. Evaluation and Optimization of Functional and Antinutritional Properties of Aquafaba. Legume Sci. 2020, 2, e30. [CrossRef] 10. Buhl, T.F.; Christensen, C.H.; Hammershøj, M. Aquafaba as an Egg White Substitute in Food Foams and Emulsions: Protein Composition and Functional Behavior. Food Hydrocoll. 2019, 96, 354–364. [CrossRef] 11. Lafarga, T.; Villaró, S.; Bobo, G.; Aguiló-Aguayo, I. Optimisation of the PH and Boiling Conditions Needed to Obtain Improved Foaming and Emulsifying Properties of Chickpea Aquafaba Using a Response Surface Methodology. Int. J. Gastron. Food Sci. 2019, 18, 100177. [CrossRef] 12. Huang, S.; Liu, Y.; Zhang, W.; Dale, K.J.; Liu, S.; Zhu, J.; Serventi, L. Composition of Legume Soaking Water and Emulsifying Properties in Gluten-Free Bread. Food Sci. Technol. Int. 2017, 24, 232–241. [CrossRef] [PubMed] 13. Tan, C.; McClements, D.J. Application of Advanced Emulsion Technology in the Food Industry: A Review and Critical Evaluation. Foods 2021, 10, 812. [CrossRef] [PubMed] 14. Xu, Y.-T.; Tang, C.-H.; Binks, B.P. High Internal Phase Emulsions Stabilized Solely by a Globular Protein Glycated to Form Soft Particles. Food Hydrocoll. 2020, 98, 105254. [CrossRef] 15. Vélez-Erazo, E.M.; Bosqui, K.; Rabelo, R.S.; Kurozawa, L.E.; Hubinger, M.D. High Internal Phase Emulsions (HIPE) Using Pea Protein and Different Polysaccharides as Stabilizers. Food Hydrocoll. 2020, 105, 105775. [CrossRef] 16. Zuo, Z.; Zhang, X.; Li, T.; Zhou, J.; Yang, Y.; Bian, X.; Wang, L. High Internal Phase Emulsions Stabilized Solely by Sonicated Quinoa Protein Isolate at Various PH Values and Concentrations. Food Chem. 2022, 378, 132011. [CrossRef] 17. Horwitz, W. Ofﬁcial Method of Analysis, 13th ed.; Association of Analytical Chemists: Washington, DC, USA, 1980. 18. Bligh, E.G.; Dyer, W.J. A Rapid Method of Total Lipid Extraction and Puriﬁcation. Can. J. Biochem. Physiol. 1959, 37, 911–917. [CrossRef] 19. Meurer, M.C.; de Souza, D.; Marczak, L.D.F. Effects of Ultrasound on Technological Properties of Chickpea Cooking Water (Aquafaba). J. Food Eng. 2020, 265, 109688. [CrossRef] 20. Shim, Y.Y.; Mustafa, R.; Shen, J.; Ratanapariyanuch, K.; Reaney, M.J.T. Composition and Properties of Aquafaba: Water Recovered from Commercially Canned Chickpeas. J. Vis. Exp. 2018, 132, e56305. [CrossRef] 21. Raikos, V.; Hayes, H.; Ni, H. Aquafaba from Commercially Canned Chickpeas as Potential Egg Replacer for the Development of Vegan Mayonnaise: Recipe Optimisation and Storage Stability. Int. J. Food Sci. Technol. 2020, 55, 1935–1942. [CrossRef] 22. Mustafa, R.; He, Y.; Shim, Y.Y.; Reaney, M.J.T. Aquafaba, Wastewater from Chickpea Canning, Functions as an Egg Replacer in Sponge Cake. Int. J. Food Sci. Technol. 2018, 53, 2247–2255. [CrossRef] Foods 2022, 11, 1588 15 of 15 23. Raikos, V.; Juskaite, L.; Vas, F.; Hayes, H.E. Physicochemical Properties, Texture, and Probiotic Survivability of Oat-Based Yogurt Using Aquafaba as a Gelling Agent. Food Sci. Nutr. 2020, 8, 6426–6432. [CrossRef] [PubMed] 24. Alajaji, S.A.; El-Adawy, T.A. Nutritional Composition of Chickpea (Cicer arietinum L.) as Affected by Microwave Cooking and Other Traditional Cooking Methods. J. Food Compos. Anal. 2006, 19, 806–812. [CrossRef] 25. Guo, B.; Hu, X.; Wu, J.; Chen, R.; Dai, T.; Liu, Y.; Luo, S.; Liu, C. Soluble Starch/Whey Protein Isolate Complex-Stabilized High Internal Phase Emulsion: Interaction and Stability. Food Hydrocoll. 2021, 111, 106377. [CrossRef] 26. Gomes, A.; Costa, A.L.R.; de Assis Perrechil, F.; da Cunha, R.L. Role of the Phases Composition on the Incorporation of Gallic Acid in O/W and W/O Emulsions. J. Food Eng. 2016, 168, 205–214. [CrossRef] 27. Vélez-Erazo, E.M.; Bosqui, K.; Rabelo, R.S.; Hubinger, M.D. Effect of PH and Pea Protein: Xanthan Gum Ratio on Emulsions with High Oil Content and High Internal Phase Emulsion Formation. Molecules 2021, 26, 5646. [CrossRef] 28. Hesarinejad, M.A.; Koocheki, A.; Razavi, S.M.A. Dynamic Rheological Properties of Lepidium Perfoliatum Seed Gum: Effect of Concentration, Temperature and Heating/Cooling Rate. Food Hydrocoll. 2014, 35, 583–589. [CrossRef] 29. Youseﬁ, A.R.; Razavi, S.M.A. Dynamic Rheological Properties of Wheat Starch Gels as Affected by Chemical Modiﬁcation and Concentration. Starch—Stärke 2015, 67, 567–576. [CrossRef] 30. Domian, E.; Manko-Jurkowska, ´ D. The Effect of Homogenization and Heat Treatment on Gelation of Whey Proteins in Emulsions. J. Food Eng. 2022, 319, 110915. [CrossRef] 31. Sridharan, S.; Meinders, M.B.J.; Sagis, L.M.C.; Bitter, J.H.; Nikiforidis, C. v Starch Controls Brittleness in Emulsion-Gels Stabilized by Pea Flour. Food Hydrocoll. 2022, 131, 107708. [CrossRef] 32. Dos Santos Carvalho, J.D.; Rabelo, R.S.; Hubinger, M.D. Thermo-Rheological Properties of Chitosan Hydrogels with Hydrox- ypropyl Methylcellulose and Methylcellulose. Int. J. Biol. Macromol. 2022, 209, 367–375. [CrossRef] [PubMed] 33. Wijaya, W.; van der Meeren, P.; Wijaya, C.H.; Patel, A.R. High Internal Phase Emulsions Stabilized Solely by Whey Protein Isolate-Low Methoxyl Pectin Complexes: Effect of PH and Polymer Concentration. Food Funct. 2017, 8, 584–594. [CrossRef] [PubMed] 34. Zhou, F.-Z.; Huang, X.-N.; Wu, Z.; Yin, S.-W.; Zhu, J.; Tang, C.-H.; Yang, X.-Q. Fabrication of Zein/Pectin Hybrid Particle- Stabilized Pickering High Internal Phase Emulsions with Robust and Ordered Interface Architecture. J. Agric. Food Chem. 2018, 66, 11113–11123. [CrossRef] [PubMed]

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Foods – Multidisciplinary Digital Publishing Institute

Published: May 28, 2022

Keywords: pulses; emulsifier; stabilizers; oil structuring; HIPE; aquafaba

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Storage Stability of Conventional and High Internal Phase Emulsions Stabilized Solely by Chickpea Aquafaba

Storage Stability of Conventional and High Internal Phase Emulsions Stabilized Solely by Chickpea Aquafaba

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Storage Stability of Conventional and High Internal Phase Emulsions Stabilized Solely by Chickpea Aquafaba

Storage Stability of Conventional and High Internal Phase Emulsions Stabilized Solely by Chickpea Aquafaba

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