Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Effect of gamma radiation and storage at 4°C on the inactivation of Listeria monocytogenes, Escherichia coli and Salmonella enterica Typhimurium in Legon-18 pepper (Capsicum annuum) powder

Effect of gamma radiation and storage at 4°C on the inactivation of Listeria monocytogenes,... Objectives: Spices are low moisture foods which have been known to be contaminated with various pathogens and sun-dried Legon-18 pepper powder is not left out. Due to its contamination with various pathogens, a study was conducted to determine the effects of gamma irradiation on the decontamination of Legon-18 pepper powder and on some quality parameters. Methods: Samples were obtained from a local farmer from the Eastern Region of Ghana. Sterility tests were carried out. The samples were inoculated with known cfu/ml of Escherichia coli, Listeria monocytogenes and Salmonella enterica Typhimurium. Samples were irradiated at 1, 2, 4, and 5 kilogray (kGy). Zero kilogray served as control (unirradiated). All samples were stored at 4 C for 60  days. Enumeration of the various pathogens was done in appropriate media. Some quality parameters were determined after irradiating unsterile samples at 5 kGy and 0 kGy served as control. Capsaicinoids and carotenoids were quantified using a high performance liquid chromatography. The samples were stored at 4 C for 8 weeks. Results: A dose-dependent effect on the inactivation of the pathogens was observed (P  <  0.05). Storage time affected the inactivation of the pathogens as well (P < 0.05). Complete inactivation of the pathogens was observed at 5 kGy at day 0. Capsaicin, dihydrocapsaicin and total capsaicinoid content of the samples irradiated at 5 kGy increased at 23.64%, 14.7 % and 20.95% respectively as compared with the contents of the unirradiated samples. A gamma irradiation dose of 5 kGy caused losses of 8.11%, 8.67% and 26.54% in capsanthin, beta carotene and beta cryptoxanthin respectively. Quality parameters measured reduced with storage (P < 0.05). Conclusions: Gamma irradiation inactivated pathogens at 5 kGy. Lower doses used during the study could inactivate the pathogens but with time. All quality parameters and carotenoids quantified were affected by gamma irradiation and storage period (P < 0.05). Key words: capsaicinoids; gamma irradiation; pathogens; carotenoids. © The Author(s) 2019. Published by Oxford University Press on behalf of Zhejiang University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by- nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com Downloaded from https://academic.oup.com/fqs/article-abstract/3/4/265/5667890 by guest on 19 February 2020 266 B. T. Odai et al., 2019, Vol. 3, No. 4 plated, and incubated at 48 hours at 37°C for L.  monocytogenes Introduction and 24 hours for E. coli and S. enterica Typhimurium. One of the most widely used spice in the world has been identi- fied as red pepper (Capsicum annuum) or chili (Lee et  al., 2004). Preparation of culture and inoculation Chili, as a spice is known as the next most important vegetable The pathogens were inoculated into the samples according to the after tomato (Ochoa-Alejo and Ramirez-Malagon, 2001; Ali, procedures of Ducic et al (2016) and Cheon et al., (2015) with some 2006; Liu et al., 2013). It is produced in several countries (Rufino modifications. and Penteado, 2006; Pinto et  al., 2016). Ripened matured fruits Listeria monocytogenes inoculum was prepared by transferring are harvested, and processed into fine powder. The powder is used 0.1  ml of the stock cultures into 10  ml of tryptic soy broth (TSB) as a spice, food colourant, a flavouring (Jung et  al., 2015) and as from BD, Maryland, USA. The inoculum was incubated at 37°C for a sauce in Ghana, a special sauce known as ‘shito’ is produced 24 hours. A loop of the pathogen was taken and incubated in TSB (Doku, 2015). in falcon tubes on a shaker for 24 hours at 37°C. The cells were har- Processed spices (including chili powder) have been known to be vested and centrifuged for 10 minutes at 3000 g at a temperature of reservoirs of microorganisms (Bhunia, 2018; Kahraman and Ozmen, 4°C. The formed pellets formed were washed and re-suspended in 2009; DOH/VICTORIA/AU, 2010; Jung et  al., 2015) due to the 10 ml of 0.1% PBS and adjusted to yield a final cell concentration of source of these and processing methods (Buckenhuskes and Rendlen, approximately 10 CFU/ml. 2004; Jung et  al., 2015). Chili has been indicated that pepper can 7 Stock cultures of E. coli and S. enterica Typhimurium were stored have high microbial contamination of viable counts exceeding 10 at −80°C in 0.7 ml of Tryptic Soy Broth (TSB; Difco) and 0.3 ml of colony-forming unit (cfu) per gram with most of these being spore 50% glycerol were streaked onto Tryptic Soy Agar (TSA; Difco) and formers (Boer et al., 1985; Piggott and Othman, 1993). later incubated at 37°C and stored at 4°C for 24 hours. A loop of each Microbial decontamination methods that have been used in of the pathogens was taken, incubated in TSB in falcon tubes on a spice including chili are the use of fumigants and irradiation tech- shaker at 37°C for a 24-hour period. Cells were harvested by centri- niques (Gregoire et  al., 2003; Schweiggert et  al., 2007; Rico et  al., fugation at 4000 g for 20 minutes at 4°C. These were washed thrice 2010; Witkowska et al., 2011; Kim et al., 2013; Cheon et al., 2015; with phosphate-buffered saline (PBS). Final pellets were re-suspended Jung et al., 2015), however some of these methods have been iden- 7 8 in 10 ml of PBS which was approximately 10 –10 cfu/ml. tified to adversely affect quality parameters of pepper powder and Approximately, equal proportions of the various pathogens were others as carcinogens (Tainter and Grenis, 2001; Almela et al., 2002; used to prepare a cocktail which was used for the inoculation of the Lilie et  al., 2007; Schweiggert et  al., 2007). The Joint Food and pepper powder samples. One millilitre of the cocktail was added to Agriculture Organization (FAO), the International Atomic Energy 10  g of the samples in sterile pouches (dimensions of 0.118 m in Agency (IAEA), and the World Health Organization (WHO) have 5 6 width and 0.170 m in length) which corresponded to 10 –10 of approved the use of gamma irradiation for the decontamination of the various pathogens. Inoculated pepper samples were thoroughly foods and it is used in over 51 countries (WHO, 1981). In light of mixed and dried in a biosafety hood for an hour. this, a study was conducted to determine the effect of gamma ir- radiation on the decontamination of notable pathogens in Legon-18 Sample irradiation pepper powder, which is one of the most consumed pepper powder in Ghana (MOFA, 2007; Sualihu, 2012; Doku, 2015). Inoculated pepper samples in the pouches were irradiated at a dose rate of 2.01 kGy/h at 1, 2, 4, and 5 kGy, and unirradiated (0 kGy) samples were used as control. Materials and methods Enumeration of pathogens Microbiological analysis The pathogens used in the study were enumerated according to the procedures of Jeong et al., (2010), Cheon et al. (2015), Deng et al. Source of samples (2015), and Ducic et  al. (2016) with some modifications. A  90  ml The samples that were used during the study were collected from a of sterile PBS was poured into 10  g of the inoculated samples in local farmer in the Eastern Region of Ghana. The pepper powder sterile stomacher bags and homogenized. Serial dilutions of the sam- was obtained from matured harvested, dried, and milled samples. ples were carried out and spread plated under sterile conditions onto PLS, CT-SMAC, and XLD agars (BD) for L. monocytogenes, E. coli, Sterility tests and S. Typhimurium, respectively. Listeria monocytogenes was incu- The samples were used for the experiment were exposed to gamma bated for 48 hours at 37°C and E. coli and S. Typhimurium. −1 irradiation dose of 20 kilogray (kGy) at a dose rate of 1.97 kGyh at the Radiation Technology Centre located at premises of the Analysis of chemical composition Biotechnology and Nuclear Agriculture Research Institute of the The chemical composition of the samples analysed were capsaicinoids Ghana Atomic Energy Commission for the purpose of removing and carotenoids. background microflora (Deng et  al., 2015). Samples were spread plated on selective media [Cefixime tellurite sorbitol MacConkey Capsaicinoids (CT-SMAC) Becton Dickinson Diagnostic Systems (BD) for E. coli; Capsaicinoids analysed in the samples were capsaicin and Palcam Listeria Selective (PLS) agar (BD) for L. monocytogenes and dihydrocapsaicin, which are the main capsaicinoids responsible for Xylose Lysine Deoxychocolate (XLD) for S. enterica Typhimurium] the hotness of chili pepper (Lu et al., 2017). under sterile conditions to confirm the sterility of the samples (Jeong et al., 2010; Deng et al., 2015). Ten grams of the samples from sterile pouches were weighed into sterile stomacher pouches (Seward, UK) Source of capsaicinoids and 90 ml of sterile buffered saline water was added. The samples Standards of the capsaicinoids were obtained from Extrasynthese that were irradiated were homogenized, serially diluted, spread (Lyon, France) and used for the study. Downloaded from https://academic.oup.com/fqs/article-abstract/3/4/265/5667890 by guest on 19 February 2020 Effect of gamma radiation and storage at 4°C Listeria monocytogenes, Escherichia coli, 2019, Vol. 3, No. 4 267 Extraction which was equipped with a revered phase column SunFire TM C (5 µm, 4.6 × 150 mm; Waters) thermostated at 30°C for both quali- Extraction of the capsaicinoids of interest was done according tative and quantitative analysis. Capsaicinoids were separated by an to the procedure of Barbero et  al. (2006). The pressurized liquid isocratic mixture of water: acetonitrile 55:44 v/v. Detection wave- extractor (Fluid Management Systems, USA) was used for the ex- length was set at 280 nm (Giuffrida et al., 2013). Calibration curves traction of the two main capsaicinoids. One gram of powdered of the standards were drawn using Microsoft Excel, 2010. Legon-18 pepper samples was weighed and contents extracted using accelerated solvent extractor equipped with a 100-ml stain- less steel extraction cells. Loaded cells with the pepper samples Total capsaicinoids and Scoville Heat Units mixed with inert sea sand which had been homogenized, were filled Total capsaicinoids and Scoville Heat Units (SHU) were computed with 90% ethanol to a pressure of 1500 psi. Heat was applied for according to the procedure of Aguiar et  al. (2016) and Jung et  al. the initial period of heat-up time; static extraction was effected (2015) and Orellana-Escobedo et  al. (2013), respectively. Total after all valves were closed. Contents of the cell were rinsed with capsaicinoids (TC) expressed as the extraction solvent and purged with N gas for 120 seconds. The TC  =  capsaicin + dihydrocapsaicin; and SHU were expressed extracts were collected from the cells after depressurization of the as SHU = [(% dihydrocapsaicin × 16.1) + (% capsaicin × 16.1)] × system (Barbero et al., 2006). 10,000 Carotenoids Quantification The main carotenoids analysed during the study were beta carotene Sample extracts were filtered through a 0.45-µm Millipore mem- and cryptoxanthin, capsanthin and zeaxanthin. brane filter and injected into an HPLC PDA (PerkinElmer Flexar), Table 1. Survival of E. coli after gamma irradiation and during storage at 4°C in powdered Legon-18 pepper (C. annuum). -1 Storage Microbial Count (log cfug ) Days 0 kGy 1 kGy 2 kGy 4 kGy 5 kGy Aa Ba Ca Da 0 6.69 ± 0.08 5.17 ± 0.11 4.59 ± 0.11 3.51 ± 0.11 ND Ab Bb Cb Db 2 6.43 ± 0.09 4.84 ± 0.11 4.24 ± 0.11 3.11 ± 0.11 ND Ac Bc Cc Dc 5 6.24 ± 0.08 4.44 ± 0.11 3.94 ± 0.11 2.81 ± 0.15 ND Ad Bd Cd Dd 12 5.67 ± 0.11 4.24 ± 0.11 3.66 ± 0.19 2.41 ± 0.15 ND Ae Bd Ce De 21 4.85 ± 0.09 4.07 ± 0.11 3.03 ± 0.09 2.11 ± 0.15 ND Af Ae Be Cf 30 3.53 ± 0.09 3.43 ± 0.09 2.87 ± 0.13 1.78 ± 0.12 ND 45 ND ND ND ND ND 60 ND ND ND ND ND Least Significant Difference: Means with the same letters (upper cases) in the same row are not significantly (P > 0.05) different from each other and means with the same letters in the same column (lower case, doses per day) are not significantly different (P > 0.05) from each other. Key: ND = not detected. Table 2. Stepwise regression analysis for the inactivation of E. coli in powdered Legon-18 pepper (C. annuum) stored at 4°C. Step Change Step (P value) Final (P value) R adjusted (%) 1 Add X 0.000* 0.000* 39.309 2 Add X 0.000* 0.000* 76.751 3 Add X *X 0.000* 0.000* 91.302 1 2 Key: X = storage days; X = doses (kGy) of gamma irradiation. 1 2 Table 3. Survival of S. Typhimurium after gamma irradiation and during storage at 4°C in powdered Legon-18 pepper (C. annuum). -1 Storage Days Microbial Count (log cfug ) 0 kGy 1 kGy 2 kGy 4 kGy 5 kGy Aa Ba Ca Da 0 6.49 ± 0.08 5.57 ± 0.11 5.37 ± 0.07 4.40 ± 0.09 ND Aa Ba Cb Db 2 6.38 ± 0.08 5.55 ± 0.11 5.18 ± 0.05 3.89 ± 0.08 ND Ab Bb Cc Dc 5 5.72 ± 0.11 5.32 ± 0.11 5.00 ± 0.11 3.65 ± 0.08 ND Abc Bc Cd Dd 12 5.62 ± 0.11 5.10 ± 0.11 4.80 ± 0.09 3.44 ± 0.08 ND Ac Bd Ce De 21 5.52 ± 0.11 4.90 ± 0.09 4.60 ± 0.09 3.02 ± 0.09 ND Ad Be Cf Df 30 5.12 ± 0.11 4.60 ± 0.09 3.65 ± 0.08 2.72 ± 0.11 ND Ad Bf Cg Dg 45 4.99 ± 0.11 3.79 ± 0.08 2.88 ± 0.11 1.46 ± 0.13 ND 60 4.65 ± 0.09 ND ND ND ND Least Significant Difference: Means with the same letters (upper cases) in the same row are not significantly (P > 0.05) different from each other and means with the same letters in the same column (lower case, doses per day) are not significantly different (P > 0.05) from each other. Key: ND = not detected. Downloaded from https://academic.oup.com/fqs/article-abstract/3/4/265/5667890 by guest on 19 February 2020 268 B. T. Odai et al., 2019, Vol. 3, No. 4 Source HPLC injection. Each carotenoid was chromatographically separ- ated by an AQUA 5u C 125A (150 × 4.60, 5 µm) reversed-phase Standards of beta carotene, capsanthin, zeaxanthin, and beta column with a gradient of acetone:water at the beginning 75:25. cryptoxanthin were obtained from Extrasynthese (Lyon, France). Microsoft Excel, 2010 was used to draw the calibration curves of the standards. Extraction One gram of the pepper samples was weighed and contents ex- Data analysis tracted using the accelerated solvent extractor equipped with 100-ml stainless steel extraction cells. The cells were loaded with the hom- StatGraphics Centurion XV.I.  and Least Significant Difference ogenized samples mixed with inert sea sand. The cells were filled (P < 0.05) were used to analyse the data obtained and means separ- with 90% ethanol to a pressure of 1500 psi. Heat was applied for ated, respectively. the initial period of heat-up time, after which static extraction took place after all the valves were closed. The cells were rinsed with the extraction solvent and purged with N gas for 2 minutes. Extracts Results and discussion from the cells were collected from the cells with 20 ml falcon tubes Gamma irradiation has been used for the decontamination of spices after depressurization of the system. and other foods. The effects of gamma irradiation on microorgan- isms in foods lead to the inactivation of such pathogens (Ban and Quantification Kang, 2014; Deng et al., 2015; Yu et al., 2017). The carotenoids studied were quantified using an HPLC (Topuz and Legon-18 pepper samples were contaminated with pathogens Odzemir, 2004). such as E. coli, L. monocytogenes, and S. Typhimurium and exposed Extracts from the samples were filtered through a 0.45-µm mem- to gamma irradiation at various doses to determine its effect on their brane filter (Millipore), into a glass vial (2  ml) and then used for inactivation. Table 4. Stepwise regression analysis for the inactivation of S. Typhimurium in powdered Legon-18 pepper (C. annuum) stored at 4°C. Step Change Step (P value) Final (P value) R Adjusted (%) 1 Add X 0.000* 0.000* 60.892 2 Add X 0.000* 0.000* 80.360 3 Add (X ) 0.000* 0.000* 82.376 4 Add (X ) 0.003* 0.003* 83.556 5 Add X *X 0.011* 0.011* 84.334 1 2 Key: X = storage days; X = doses (kGy) of gamma irradiation. 1 2 Table 5. Survival of L. monocytogenes after gamma irradiation and during storage at 4°C in powdered Legon-18 pepper (C. annuum). −1 Storage Microbial Count (log cfug ) Days 0 kGy 1 kGy 2 kGy 4 kGy 5 kGy Aa Ba Ca Da 0 6.26 ± 0.08 5.87 ± 0.11 4.97 ± 0.11 4.83 ± 0.12 ND Aa Bb Cb Db 2 6.15 ± 0.08 5.42 ± 0.11 4.46 ± 0.09 3.81 ± 0.11 ND Aa Bb Cc Dc 5 6.04 ± 0.08 5.28 ± 0.11 4.26 ± 0.09 3.12 ± 0.11 ND Ab Bc Cc Dd 12 5.78 ± 0.11 5.02 ± 0.11 4.10 ± 0.09 2.86 ± 0.11 ND Ac Bc Cd Dde 21 5.42 ± 0.11 4.90 ± 0.09 3.84 ± 0.09 2.66 ± 0.13 ND Ad Bd Ce De 30 5.18 ± 0.11 4.30 ± 0.09 3.15 ± 0.08 2.46 ± 0.13 ND Ad Be Cf Df 45 5.07 ± 0.11 3.19 ± 0.08 2.47 ± 0.11 1.96 ± 0.13 ND Ae Bf 60 4.85 ± 0.09 2.22 ± 0.11 ND ND ND Least Significant Difference: Means with the same letters (upper cases) in the same row are not significantly (P > 0.05) different from each other and means with the same letters in the same column (lower case, doses per day) are not significantly different (P > 0.05) from each other. Key: ND = not detected. Table 6. Stepwise regression analysis for the inactivation of L. monocytogenes in powdered Legon-18 pepper (C. annuum) stored at 4°C. Step Change Step (P value) Final (P value) R Adjusted (%) 1 Add X 0.000* 0.000* 68.864 2 Add X 0.000* 0.000* 84.500 3 Add (X ) 0.011 0.011* 85.223 4 Add X *X 0.053** 0.053** 85.579 2 2 Key: X = storage days; X = doses (kGy) of gamma irradiation. 1 2 Downloaded from https://academic.oup.com/fqs/article-abstract/3/4/265/5667890 by guest on 19 February 2020 Effect of gamma radiation and storage at 4°C Listeria monocytogenes, Escherichia coli, 2019, Vol. 3, No. 4 269 Sterility of samples There was no detection of the pathogens after the samples were ex- posed to sterility dose. This observation was similar to the study of Deng et al. (2015). Inactivation of E. coli Table 1 indicates the effect of gamma irradiation on the survival of E.  coli after exposure to gamma irradiation. There was a general reduction in the count (log cfu/g) of E.  coli in the pepper samples at all the doses of gamma irradiation in the pepper samples during the period of study (P  <  0.05). Inactivation of the pathogen was dose-dependent which is similar to the observations of Deng et  al. (2015), Waje et al. (2008), Ban and Kang (2014), Carcel et al., 2015, and Jeong and Kang (2017). This observation may be attributed to the inability of the pathogen to recover from the injuries caused by gamma irradiation, the inability of the injured cells to adopt to their environment (Wu et al., 2008). A stepwise regression analysis (Table 2) was used to determine the effect of gamma irradiation and storage (P < 0.05; R  = 91.52% or 0.9152) on the inactivation of E. coli. A model computed from the regression analysis is indicated as Inactivation of E. coli (log cfu/g)= 6.021 − 0.1078 X1 − 1.1255 X2 + 0.0200 X1 ∗ X2 (1) Where X = storage days X = doses (kGy) of gamma irradiation Inactivation of S. Typhimurium Inactivation of S. Typhimurium is indicated in Table 3. A reduction in the microbial load (log cfu/g) was observed (P < 0.05) from the first day to the end of the study. Gamma irradiation and storage affected the microbial count (P  <  0.05; Table 4) of the pathogen. Jeong and Kang (2017) and Ban and Kang (2014) had indicated the effect of gamma irradiation on the inactivation of S. Typhimurium which was dose dependent. In this study, a dose-dependent effect was observed. This observation may be due to the production of free radicals, reactive oxygen species, and other products from gamma irradiation which might have interacted with cellular composition, leading to inactivation (Yong et  al., 2015). There was no detection at 5 kGy. The effect of gamma irradiation and storage on the inactivation of S. Typhimurium was determined using the stepwise regression (Table 4) analysis (P < 0.05; R  = 0.8500 or 85.00%). The model (2) expressed the inactivation of the pathogen. Inactivation of S. Typhimurium (log cfu/g)= 6.294 − 0.0196X −0.379X − 0.0001(X )(2) 2 1 −0.1375(X ) + 0.0056X ∗ X 2 1 2 Inactivation of L. monocytogenes The microbial count of the L. monocytogenes in the samples ranged from no detection to about 6 log cfu/g (Table 5). A  general reduc- tion in the count of L. monocytogenes in the pepper samples from the onset to the end of the study. There was a dose-dependent effect of gamma irradiation on the inactivation of the pathogen is similar to literature (Rico et  al., 2010; Mukhopadhyay et  al., 2013; Jeong and Kang, 2017). Inactivation was completely achieved at a dose of 5 kGy (no detection). Jeong and Kang (2017) and Waje et al. (2008) had indicated the effect of gamma irradiation on the inactivation Table 7. Effect of gamma irradiation and storage on some quality parameters of Legon-18 pepper (C. annuum) powder at 4°C. Storage Capsaicin (mg/100 g) Dihydrocapsaicin (mg/100 g) Total capsaicinoids (mg/100 g) SHU (×10,000) Weeks 0 kGy 5 kGy 0 kGy 5 kGy 0 kGy 5 kGy 0 kGy 5 kGy Ia Hb Ga Hb Ia Ib Ia Ib 0 178.74 ± 1.30 221.00 ± 2.29 77.12 ± 1.84 88.48 ± 1.11 255.87 ± 2.57 309.47 ± 3.32 4119.46 ± 41.33 4982.51 ± 53.49 Ha Hb Fa Hb Ha Hb Ha Hb 1 177.18 ± 0.28 217.35 ± 0.37 75.48 ± 0.02 88.76 ± 0.04 252.65 ± 0.39 306.12 ± 0.36 4067.74 ± 62.26 4928.46 ± 57.45 Ga Gb Ea Gb Ga Gb Ga Gb 2 173.25 ± 0.00 216.88 ± 0.11 74.29 ± 0.05 87.21 ± 0.00 247.54 ± 0.30 304.09 ± 0.11 3985.45 ± 36.96 4865.9118.19 Fa Fb Ea Fb Fa Fb Fa Fb 3 165.73 ± 0.77 213.72 ± 0.17 73.35 ± 0.12 86.38 ± 0.37 239.08 ± 1.06 300.10 ± 0.47 3849.15 ± 17.01 4831.62 ± 76.45 Ea Eb Da Eb Ea Eb Ea Eb 4 161.51 ± 0.15 210.53 ± 0.00 66.15 ± 0.00 85.32 ± 0.15 227.66 ± 0.21 295.85 ± 0.15 3665.39 ± 33.07 4763.26 ± 23.72 Da Db Ca Db Da Db Da Db 5 154.40 ± 1.22 207.31 ± 0.39 64.46 ± 0.63 83.56 ± 0.51 218.86 ± 1.14 290.86 ± 0.20 3523.64 ± 18.43 4682.88 ± 32.45 Ca Cb Ca Cb Ca Cb Ca Cb 6 146.93 ± 0.00 204.44 ± 0.73 63.82 ± 0.58 82.62 ± 0.39 210.75 ± 0.76 287.06 ± 0.34 3393.05 ± 12.30 4621.74 ± 54.33 Ba Bb Ba Bb Ba Bb Ba Bb 7 144.74 ± 0.00 198.95 ± 0.09 61.97 ± 0.00 80.84 ± 0.10 206.70 ± 0.05 279.79 ± 0.17 3327.91 ± 0.78 4504.64 ± 27.11 Aa Ab Aa Ab Aa Ab Aa Ab 8 140.34 ± 0.00 190.57 ± 0.11 59.80 ± 0.15 80.05 ± 0.18 200.14 ± 0.42 270.61 ± 0.14 3222.23 ± 67.96 4356.87 ± 22.17 Least Significant Difference: Means with the same letters (upper case, within the same column) are not significantly (P > 0.05) different from each other and means with the same letters in the same row (lower case, doses within a particular week) are not significantly different (P > 0.05) from each other. Downloaded from https://academic.oup.com/fqs/article-abstract/3/4/265/5667890 by guest on 19 February 2020 270 B. T. Odai et al., 2019, Vol. 3, No. 4 Table 8. Effect of gamma irradiation and storage on some carotenoids in Legon-18 pepper (C. annuum) powder at 4 C. Storage Capsanthin (mg/100 g) Beta carotene (mg/100 g) Beta cryptoxanthin (mg/100 g) weeks 0 kGy 5 kGy 0 kGy 5 kGy 0 kGy 5 kGy Fb Ga Ib Ia Hb Da 0 1.48 ± 0.00 1.36 ± 0.02 10.27 ± 0.00 9.38 ± 0.00 2.11 ± 0.02 1.55 ± 0.01 Eb Ga Hb Ha Gb Da 1 1.46 ± 0.01 1.35 ± 0.01 10.04 ± 0.00 9.24 ± 0.00 2.05 ± 0.00 1.59 ± 0.00 Db GFa Gb Ga Gb Da 2 1.42 ± 0.00 1.33 ± 0.00 9.92 ± 0.00 8.78 ± 0.00 2.03 ± 0.02 1.56 ± 0.03 Db EFa Fb Fa Fb Ca 3 1.41 ± 0.00 1.30 ± 0.00 9.43 ± 0.00 8.48 ± 0.00 1.95 ± 0.00 1.48 ± 0.01 Db DEa Eb Ea Eb BCa 4 1.41 ± 0.00 1.27 ± 0.00 9.20 ± 0.00 8.23 ± 0.02 1.87 ± 0.00 1.43 ± 0.02 Db DCa Db Da Db Ba 5 1.41 ± 0.00 1.26 ± 0.00 8.91 ± 0.02 8.21 ± 0.00 1.80 ± 0.01 1.40 ± 0.00 Cb Ca Cb a Cb Aa 6 1.38 ± 0.02 1.23 ± 0.00 8.69 ± 0.07 7.91 ± 0.00C 1.71 ± 0.00 1.30 ± 0.00 Bb Ba Bb Ba Bb Aa 7 1.35 ± 0.02 1.20 ± 0.00 8.48 ± 0.00 7.26 ± 0.00 1.66 ± 0.00 1.24 ± 0.00 Ab Aa Ab Aa Ab Aa 8 1.32 ± 0.02 1.14 ± 0.04 8.17 ± 0.00 6.01 ± 0.00 1.50 ± 0.03 1.24 ± 0.11 Least Significant Difference: Means with the same letters (upper case, within the same column) are not significantly (P > 0.05) different from each other and means with the same letters in the same row (lower case, doses within a particular week) are not significantly different (P > 0.05) from each other. of L.  monocytogenes. The observed pattern is similar to the obser- Effect of gamma irradiation on carotenoids during storage vation of Yu et al. (2017), Jeong and Kang (2017), and Waje et al. The carotenoids in the pepper samples analysed were capsanthin, (2008). The irradiation effects might have led to injuries to cells as beta carotene, beta cryptoxanthin, and zeaxanthin. Zeaxanthin was well as the effects of gamma irradiation on the cellular components below the detection point hence no data on this. The other carot- (Yong et al., 2015). enoid contents (Table 8) reduced after exposure to gamma irradi- A significant effect (P < 0.05) of gamma irradiation and storage ation at 5 kGy as compared to the contents of the samples that were was observed from the stepwise regression analysis (Table 6), which not irradiated (P < 0.05). Gamma irradiation at 5kGy caused losses had an R  = 86.07% or 0.8607. 8.11%, 8.67%, and 26.54% in capsanthin, beta carotene, and beta Model (3) from the regression analysis for the inactivation is cryptoxanthin, respectively in the pepper samples as compared with expressed as the unirradiated samples. There was a general reduction in the ca- rotenoid content during storage (P < 0.05). These observations have been reported elsewhere in literature (Pérez-Gálvez and Mínguez- Inactivation of Mosquera, 2001; Topuz and Ozemir, 2003; Kim et  al., 2004; Kim L.monocytogenes (log cfu/g)= 6.470 − 0.0514X − 0.645X 1 2 et al., 2006; Rico et al., 2010; Giuffrida et al., 2014; Guadarrama- −0.0820(X ) + 0.0039X ∗ X 2 1 2 Lezama et  al., 2014; Jung et  al., 2015). The reduced content after irradiation and during storage may due to the secondary effects Where X = storage days of gamma irradiation, component oxidation, form of the milled X = doses (kGy) of gamma irradiation sun-dried pepper samples, and the structure of the carotenoids. Chemical composition Conclusions Effect of gamma irradiation on capsaicinoids during storage Gamma irradiation and storage had significant effect (P  <  0.05) The capsaicinoids analysed in the study were capsaicin and on the inactivation and quality parameters determined in Legon- dihydrocapsaicin (Table 7). Total capsaicinoids and SHU were 18 pepper powder. Gamma irradiation can be used for the decon- computed as described earlier. Samples that were irradiated at 5 tamination of pathogens such E.  coli, L.  monocytogenes, and S. kGy had higher values as compared to the samples that were not ir- Typhimurium in Legon-18 pepper powder. A  dose of 5 kGy can radiated. Samples irradiated at 5 kGy recorded percentage increase inactivate all the pathogens immediately after exposure to gamma of 23.64%, 14.7%, and 20.95% in capsaicin, dihydrocapsaicin, irradiation, not withstanding, doses such as 2 and 4 kGy can also and total capsaicinoids, respectively as compared with the control. be used for the inactivation of the pathogens used in the study but There was a general reduction in the capsaicinoid content of the subject to storage time of 60 days. E. coli could be inactivated at a samples during storage. Since TC and SHU were computed from dose of 1 kGy at day 30. Samples irradiated had lower carotenoid the capsaicinoids analysed, similar patterns of were observed. contents as compared to the unirradiated. Zeaxanthin was below the Giuffrida et  al. (2014), Yu et  al. (2017), and Topuz and Odzemir detection limit. Higher values of hotness indices were observed in the (2004) in a previous indicated that gamma and storage caused a re- irradiated but not in the unirradiated samples. duction in the content of capsaicinoids, however, Byun et al. (1996) and Lee et al. (2004) indicated the stability of capsaicinoids below 15kGy. The observed higher contents in the samples irradiated Acknowledgements are similar to the observations of Giuffrida et al. (2014), Yu et al. Our profound gratitude goes to the technologists at the Department of (2017), and Topuz and Odzemir (2004) and this may be attributed Bacteriology, Noguchi Memorial Institute for Medical Research, University to the induction of water deficit by gamma irradiation (Farkas, of Ghana, Legon, Accra-Ghana for the assistance rendered during the micro- 2006). The general reduction in the capsaicinoids, TC, and SHU biology aspect, the Radiation Technology Centre (BNARI-GAEC) for carrying during storage may be due to the effect of milling and residue en- out dosimetry for dose delivery and Central Laboratory of KNUST for the zymatic action (Wang et al., 2009). analysis of capsaicinoids and carotenoids in the samples. Downloaded from https://academic.oup.com/fqs/article-abstract/3/4/265/5667890 by guest on 19 February 2020 Effect of gamma radiation and storage at 4°C Listeria monocytogenes, Escherichia coli, 2019, Vol. 3, No. 4 271 Giuffrida,  D., Dugo,  P., Torre,  G., Bignardi,  C., Cavazza,  A., Corrandi,  C., Funding Dugo,  G. (2013). Characterization of 12 Capsicum varieties by evalu- Funds were obtained from the authors from the collection of data, its analysis, ation of their carotenoid and pungency determination. Food Chemistry, and interpretation. 140:794–802. Giuffrida,  D., Dugo,  P., Torre,  G., Bignardi,  C., Cavazza,  A., Corrandi,  C., Dugo,  G. (2014). Evaluation of carotenoid and capsaicinoid and Conflict of interest capsaicinoid contents in powder of red chili peppers during one year of Authors hereby certify that there are no conflicts of interest with any organ- storage. Food Research International, 65: 163–170. ization, financial, or other regarding the material discussed in the manuscript Gregoire,  O., Cleland,  M.  R., Mittendorfer,  J., Dababneh,  S., Ehlermann,  D.  A.  E., Fan,  X., et  al. (2003). Radiological safety of food irradiation with high energy X-rays: theoretical expectations and experi- References mental evidence. Radiation Physics and Chemistry, 67: 169–183. Aguiar, A. C., Silva, L. P. S., de Rezende, C. A., Barbero, G. F., Martinez, J. Guadarrama-Lezama,  A.  Y., Jaramillo-Flores,  E., Gutierrez-Lopez,  G.  F., (2016). Encapsulation of pepper oleoresin by supercritical fluid extraction Perez-Alonso,  C., Dornates-Alvarez,  L., Alamilla-Beltran,  L. (2014). Ef- of emulsions. The Journal of Supercritical Fluids, 112:37–43. fects of storage temperature and water activity on the degradation of Ali, M. (ed.). (2006). Chilli (Capsicum spp) Food Chain Analysis: Setting Re- carotenoids contained in microencapsulated chili extract. Drying Tech- search Priorities in Asia. AVRDC-The World Vegetable Centre, Technical nology, 32:1435–1447. Bulletin No. 38, AVRDC Publication, Shanhua, Taiwan, pp. 1–253. Jeong, A-R., Jo, M. J., Koo, M., Ku, K-H., Park, J-B., Kim, H. J. (2010). Micro- Almela, L., Nieto-Sandoval, J. M., Fernández López, J. A. (2002). Microbial bial contamination of fresh-red pepper and packaged-red pepper powder inactivation of paprika by a high-temperature short-X time treatment. In- in South Korea. Journal of Food Science and Nutrition, 15:233–238. fluence on color properties. Journal of Agricultural and Food Chemistry, Jeong,  S-G., Kang,  D-H. (2017). Inactivation of Escherichia coli O157:H7, 50: 1435–1440. Salmonella Typhimurium, and Listeria monocytogenes in ready-to-bake Ban, G. H., Kang, D. H. (2014). Effects of gamma irradiation for inactivating cookie dough by gamma and electron beam irradiation. Food Micro- Salmonella Typhimurium in peanut butter product during storage. Inter- biology, 64:172–176. national Journal of Food Microbiology, 171: 48–53. Jung, K., Song, B-S., Kim, M. J., Moon, B-G., Go, S-M., Kim, J-K., Lee, Y-J., Barbero, G. F., Palma, M., Barroso, C. G. (2006). Pressurized liquid extraction Park, J-H. (2015). Effect of X-ray, gamma ray, and electron beam irradi- of capsaicinoids from peppers. Journal of Agricultural and Food Chem- ation on the hygienic and physicochemical qualities of red pepper powder. istry, 54: 3231–3236. LWT-Food Science and Technology, 63:846–851. Bhunia,  A.  K. (2018). Foodborne Microbial Pathogens. Mechanisms and Kahraman,  T., Ozmen,  G. (2009). Quality of selected spices and herbs con- Pathogenesis. Springer Science+Business Media, LLC, New York, USA, pp. sumed in Turkey. Archiv für Lebensmittel hygiene, 60:185–191. 12–22. Kim, S., Lee, K. W., Park, J., Lee, J., Hwang I. K. (2006). Effect of drying in Boer, E. D., Spiegelenberg, W., Jansen, F. (1985). Microbiology of Spices and antioxidant activity and changes of ascorbic acid and colour by different herbs. Antonie van Leeuwenhoek, 51:435–438. drying and storage in Korean red pepper (Capsicum annuum L.). Inter- Buckenhuskes,  H.  J., Rendlen,  M. (2004). Hygienic problems of phytogenic national Journal of Food Science and Technology, 41:90–95. raw material for food production with special emphasis on herbs and Kim, S., Park, J. B. and Hwang, I. K. (2004). Composition of main carotenoids spices. Food Science and Biotechnology, 13:262–268. in Korean red pepper (Capsicum annuum, L.) and the changes of pig- Byun, M. W., Yook, H. S., Kwon, J. H., Kim, J. O. (1996). Improvement of ment stability during drying and storage process. Journal of Food Science, hygiene quality and long-term storage of dried red pepper by gamma- 69:FCT39–44. irradiation. Korean Society of Food Science and Technology, 28: 482–489. Lee,  J.  H., Sung,  T.  H., Lee,  K.  T., Kim,  M.  R. (2004). Effect of gamma- Carcel,  J.  A., Benedito,  J., Cambero,  M.  I., Cabeza,  M.  C., Ordonez,  J.  A. irradiation on colour, pungency and volatiles of Korean red pepper (2015). Modelling and optimization of the E-beam treatment of chicken powder. Journal of Food Science, 69:C585–C5591. steaks and hamburgers, considering food safety, shelf-life and sensory Lilie, M., Hein, S., Wilhelm, P., Müller, U. (2007). Decontamination of spices quality. Food and Bioproducts Processing, 96:133–144. by combining mechanical and thermal effects – an alternative approach Cheon, H-L., Shin, J-S., Park, K-H., Chung, M-S., Kang, D-H. (2015). Inacti- for quality retention. International Journal of Food Science and Tech- vation of pathogens in red pepper powder (Capsicum annuum L.) using nology, 42:190–193. combined UV-C irradiation and mild heat. Food Control, 50:441–445. Liu,  W.  Y., Kang,  W-H., Kang,  B-C. (2013). Basic information o pepper. In: Deng,  W., Wu,  G., Guo,  L., Long,  M., Li,  B., Liu,  S., Cheng,  L., Pan,  X., Genetics, Genomics and Breeding of Peppers and Eggplants. Kang, B-C., Zou, L. (2015). Effect of gamma irradiation on Escherichia coli, Salmon- Kole,  C. (eds.) CRC Press. Taylor and Francis group. LLC, Boca Raton, ella Enterica Typhimurium and Aspergillus niger in peppers. Food Science pp. 1–13. and Technology Research, 21: 241–245. Lu, M., Ho, C. T., Huang, Q. (2017). Extraction, bioavailability, and bioefficacy Department of Health, State Government of Victoria, Australia (DOH/Vic- of capsaicinoids. Journal of Food and Drug Analysis, 25: 27–36. toria/AU). 2010. Report on a survey of spices for the presence of patho- Ministry of Food and Agriculture (MOFA). (2007). Chilli Pepper Production gens - 2007. http://www.health.vic.gov.au/archive/archive2011/foodsafety/ Guide. Horticulture Export Industry Initiative, MOFA, Accra-Ghana, pp. 9. archive/microbiological.htm. Accessed 26 September 2017. Mukhopadhyay, S., Ukuku, D., Fan, X., Juneja, V. K. (2013). Efficacy of in- Doku,  S.  K. (2015). Genetic diversity studies. In: Twenty Accessions of Hot tegrated treatment of UV light and low-dose gamma irradiation on in- Pepper (Capsicum Spp L.) In Ghana. A thesis presented to the Department activation of Escherichia coli O157:H7 and Salmonella enterica on grape of Nuclear Agriculture and Radiation Processing School of Nuclear and tomatoes. Journal of Food Science, 78: M1049–M1056. Allied Sciences University of Ghana, Kwabenya-Accra, Ghana. Ochoa-Alejo,  N., Ramirez-Malagon,  R. 2001. Invited review: in vitro chilli Ducic, M., Klisara, N., Markov, S., Blagojevic, B., Vidakovic, A. (2016). The pepper biotechnology. In Vitro Cellular and Developmental Biology-Plant, fate and pasteurization of-based inactivation of Escherichia coli O157, 37:701–729. Salmonella Typhimurium and Listeria monocytogenes in dry, fermented Orellana-Escobedo,  L., Garcia-Amezquita,  L.E., Olivas,  G.  I., Ornelas- sausages. Food Control, 59:400–406. Paz, J. J., Sepulveda, D. R. (2013). Capsaicinoids content and proximate Farkas, J. (2006). Irradiation for better foods. Trends in Food Science Tech- composition of Mexican chili peppers (Capsicum spp.) cultivated in the nology, 17:148–152. State of Chihuahua. CytA-Journal of Food, 11: 179–184. Farkas,  J., Andrassy,  E. (1988). Comparative analysis of spices decontamin- Pérez-Gálvez, A., Mínguez-Mosquera, M. I. (2001). Structure-reactivity re- ated by ethylene oxide or gamma-radiation. Acta Alimentaria, 17: 77–94. lationship in the oxidation of carotenoid pigments of the pepper (Cap- Downloaded from https://academic.oup.com/fqs/article-abstract/3/4/265/5667890 by guest on 19 February 2020 272 B. T. Odai et al., 2019, Vol. 3, No. 4 sicum annuum L.). Journal of Agricultural and Food Chemistry, 49: Topuz, A., Ozdemir, F. (2003). Influences of gamma-irradiation and storage on 4864–4869. the carotenoids of sun-dried and dehydrated paprika. Journal of Agricul- Piggott, J., Othman, Z. (1993). Effect of irradiation on volatile oils of black tural and Food Chemistry, 51: 4972–4977. pepper. Food Chemistry, 46:115–119. Waje,  C.  K., Kim,  H.  K., Kim,  K.  S., Todoriki,  S., Kwon,  J.  H. (2008). Pinto, C. M. F., dos Santos, I. C., de Araujo, F. F., da Silva, T. P. (2016). Pepper Physicochemical and microbiological qualities of steamed and irradiated importance and growth. In: do Rêgo, E. R., do Rêgo, M. M., Finger, F. L, ground black pepper (Piper nigrum L.). Journal of Agricultural and Food eds. Production and Breeding of Chilli Peppers (Capsicum spp.). Springer Chemistry, 56: 4592–4596. International Publishing, Switzerland, pp. 503–545. Wang,  Y., Xia,  Y, Wang,  J., Luo,  F., Huang,  Y. (2009). Carotenoids in chili Rico, C. W., Kim, G-R., Ahn, J-J., Kim, H-K., Furuta, M., Kwon, J-H. (2010). pepper (Capsicum annuum, L.) powder as affected by heating and storage The comparative effect of steaming and irradiation on the physicochemical methods. American Society of Agricultural and Biological Engineers, 52: and microbiological properties of dried red pepper (Capsicum annum L.). 2007–2010. Food Chemistry, 119: 1012–1016. WHO. (1981). Wholesomeness of Irradiated Food. Report of a Joint FAO/ Rufino, J. L. S., Penteado, D. C. S. (2006) Importância econômica, perspectivas IAEA/WHO Expert Committee, Technical Report Series 659. World e potencialidades do Mercado para pimenta. Informe Agropecuário, Belo Health Organization, Geneva, Switzerland. p. 33. Horizonte 27:7–15 Witkowska, A. M., Hickey, D. K., Alonso-Gomez, M., Wilkinson, M. G. (2011). Schweiggert, U., Carle, R., Schieber. A., (2007). Conventional and alternative The microbiological quality of commercial herb and spice preparations used processes for spice production-a review. Trends in Food Science and Tech- in the formulation of a chicken supreme ready meal and microbial survival nology, 18: 260–268. following a simulated industrial heating process. Food Control, 22: 616–625. Sualihu,  A. (2012). Effect of Three Pre-Drying Treatments and Two Drying Wu, V. C. (2008). A review of microbial injury and recovery methods in food. Methods on the Quality of Scotch Bonnet (capsicum chinense) Grown in Food Microbiology, 25: 735–744. the Tolon/Kumbungu District of Northern Ghana. A thesis submitted to Yong,  H.  I., Kim,  H-J., Nam,  K.  C., Kwon,  J.  H., Jo,  C. (2015). Radiation Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. sensitivity of foodborne pathogens in meat byproducts with different Tainter,  D.  R., Grenis,  A.  T. (2001). Spices and Seasonings—A Food Tech- packaging. Radiation Physics and Chemistry, 115: 155–157. nology Handbook. 2nd edn. VCH, New York Wiley. Yu, W-J., Liu, H-P., Zhang, X-W., Dong, D., Jiang, Y., Sun, N-X., Liu, Y-K., Topuz,  A., Odzemir,  F. (2004). Influences of gamma irradiation and storage Yuan, J-F. (2017). Postirradiation changes of the microbiological quality, on the carotenoids of sun-dried and dehydrated paprika. Food Chemistry, aflatoxin, capsaicinoids, volatile oils, and the color of red pepper powder. 86: 509–515. Journal of Food Processing and Preservation, 1352:1–9. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Food Quality and Safety Oxford University Press

Effect of gamma radiation and storage at 4°C on the inactivation of Listeria monocytogenes, Escherichia coli and Salmonella enterica Typhimurium in Legon-18 pepper (Capsicum annuum) powder

Loading next page...
 
/lp/oxford-university-press/effect-of-gamma-radiation-and-storage-at-4-c-on-the-inactivation-of-032JUUyUh6

References (58)

Publisher
Oxford University Press
Copyright
© The Author(s) 2019. Published by Oxford University Press on behalf of Zhejiang University Press.
ISSN
2399-1399
eISSN
2399-1402
DOI
10.1093/fqsafe/fyz026
Publisher site
See Article on Publisher Site

Abstract

Objectives: Spices are low moisture foods which have been known to be contaminated with various pathogens and sun-dried Legon-18 pepper powder is not left out. Due to its contamination with various pathogens, a study was conducted to determine the effects of gamma irradiation on the decontamination of Legon-18 pepper powder and on some quality parameters. Methods: Samples were obtained from a local farmer from the Eastern Region of Ghana. Sterility tests were carried out. The samples were inoculated with known cfu/ml of Escherichia coli, Listeria monocytogenes and Salmonella enterica Typhimurium. Samples were irradiated at 1, 2, 4, and 5 kilogray (kGy). Zero kilogray served as control (unirradiated). All samples were stored at 4 C for 60  days. Enumeration of the various pathogens was done in appropriate media. Some quality parameters were determined after irradiating unsterile samples at 5 kGy and 0 kGy served as control. Capsaicinoids and carotenoids were quantified using a high performance liquid chromatography. The samples were stored at 4 C for 8 weeks. Results: A dose-dependent effect on the inactivation of the pathogens was observed (P  <  0.05). Storage time affected the inactivation of the pathogens as well (P < 0.05). Complete inactivation of the pathogens was observed at 5 kGy at day 0. Capsaicin, dihydrocapsaicin and total capsaicinoid content of the samples irradiated at 5 kGy increased at 23.64%, 14.7 % and 20.95% respectively as compared with the contents of the unirradiated samples. A gamma irradiation dose of 5 kGy caused losses of 8.11%, 8.67% and 26.54% in capsanthin, beta carotene and beta cryptoxanthin respectively. Quality parameters measured reduced with storage (P < 0.05). Conclusions: Gamma irradiation inactivated pathogens at 5 kGy. Lower doses used during the study could inactivate the pathogens but with time. All quality parameters and carotenoids quantified were affected by gamma irradiation and storage period (P < 0.05). Key words: capsaicinoids; gamma irradiation; pathogens; carotenoids. © The Author(s) 2019. Published by Oxford University Press on behalf of Zhejiang University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by- nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com Downloaded from https://academic.oup.com/fqs/article-abstract/3/4/265/5667890 by guest on 19 February 2020 266 B. T. Odai et al., 2019, Vol. 3, No. 4 plated, and incubated at 48 hours at 37°C for L.  monocytogenes Introduction and 24 hours for E. coli and S. enterica Typhimurium. One of the most widely used spice in the world has been identi- fied as red pepper (Capsicum annuum) or chili (Lee et  al., 2004). Preparation of culture and inoculation Chili, as a spice is known as the next most important vegetable The pathogens were inoculated into the samples according to the after tomato (Ochoa-Alejo and Ramirez-Malagon, 2001; Ali, procedures of Ducic et al (2016) and Cheon et al., (2015) with some 2006; Liu et al., 2013). It is produced in several countries (Rufino modifications. and Penteado, 2006; Pinto et  al., 2016). Ripened matured fruits Listeria monocytogenes inoculum was prepared by transferring are harvested, and processed into fine powder. The powder is used 0.1  ml of the stock cultures into 10  ml of tryptic soy broth (TSB) as a spice, food colourant, a flavouring (Jung et  al., 2015) and as from BD, Maryland, USA. The inoculum was incubated at 37°C for a sauce in Ghana, a special sauce known as ‘shito’ is produced 24 hours. A loop of the pathogen was taken and incubated in TSB (Doku, 2015). in falcon tubes on a shaker for 24 hours at 37°C. The cells were har- Processed spices (including chili powder) have been known to be vested and centrifuged for 10 minutes at 3000 g at a temperature of reservoirs of microorganisms (Bhunia, 2018; Kahraman and Ozmen, 4°C. The formed pellets formed were washed and re-suspended in 2009; DOH/VICTORIA/AU, 2010; Jung et  al., 2015) due to the 10 ml of 0.1% PBS and adjusted to yield a final cell concentration of source of these and processing methods (Buckenhuskes and Rendlen, approximately 10 CFU/ml. 2004; Jung et  al., 2015). Chili has been indicated that pepper can 7 Stock cultures of E. coli and S. enterica Typhimurium were stored have high microbial contamination of viable counts exceeding 10 at −80°C in 0.7 ml of Tryptic Soy Broth (TSB; Difco) and 0.3 ml of colony-forming unit (cfu) per gram with most of these being spore 50% glycerol were streaked onto Tryptic Soy Agar (TSA; Difco) and formers (Boer et al., 1985; Piggott and Othman, 1993). later incubated at 37°C and stored at 4°C for 24 hours. A loop of each Microbial decontamination methods that have been used in of the pathogens was taken, incubated in TSB in falcon tubes on a spice including chili are the use of fumigants and irradiation tech- shaker at 37°C for a 24-hour period. Cells were harvested by centri- niques (Gregoire et  al., 2003; Schweiggert et  al., 2007; Rico et  al., fugation at 4000 g for 20 minutes at 4°C. These were washed thrice 2010; Witkowska et al., 2011; Kim et al., 2013; Cheon et al., 2015; with phosphate-buffered saline (PBS). Final pellets were re-suspended Jung et al., 2015), however some of these methods have been iden- 7 8 in 10 ml of PBS which was approximately 10 –10 cfu/ml. tified to adversely affect quality parameters of pepper powder and Approximately, equal proportions of the various pathogens were others as carcinogens (Tainter and Grenis, 2001; Almela et al., 2002; used to prepare a cocktail which was used for the inoculation of the Lilie et  al., 2007; Schweiggert et  al., 2007). The Joint Food and pepper powder samples. One millilitre of the cocktail was added to Agriculture Organization (FAO), the International Atomic Energy 10  g of the samples in sterile pouches (dimensions of 0.118 m in Agency (IAEA), and the World Health Organization (WHO) have 5 6 width and 0.170 m in length) which corresponded to 10 –10 of approved the use of gamma irradiation for the decontamination of the various pathogens. Inoculated pepper samples were thoroughly foods and it is used in over 51 countries (WHO, 1981). In light of mixed and dried in a biosafety hood for an hour. this, a study was conducted to determine the effect of gamma ir- radiation on the decontamination of notable pathogens in Legon-18 Sample irradiation pepper powder, which is one of the most consumed pepper powder in Ghana (MOFA, 2007; Sualihu, 2012; Doku, 2015). Inoculated pepper samples in the pouches were irradiated at a dose rate of 2.01 kGy/h at 1, 2, 4, and 5 kGy, and unirradiated (0 kGy) samples were used as control. Materials and methods Enumeration of pathogens Microbiological analysis The pathogens used in the study were enumerated according to the procedures of Jeong et al., (2010), Cheon et al. (2015), Deng et al. Source of samples (2015), and Ducic et  al. (2016) with some modifications. A  90  ml The samples that were used during the study were collected from a of sterile PBS was poured into 10  g of the inoculated samples in local farmer in the Eastern Region of Ghana. The pepper powder sterile stomacher bags and homogenized. Serial dilutions of the sam- was obtained from matured harvested, dried, and milled samples. ples were carried out and spread plated under sterile conditions onto PLS, CT-SMAC, and XLD agars (BD) for L. monocytogenes, E. coli, Sterility tests and S. Typhimurium, respectively. Listeria monocytogenes was incu- The samples were used for the experiment were exposed to gamma bated for 48 hours at 37°C and E. coli and S. Typhimurium. −1 irradiation dose of 20 kilogray (kGy) at a dose rate of 1.97 kGyh at the Radiation Technology Centre located at premises of the Analysis of chemical composition Biotechnology and Nuclear Agriculture Research Institute of the The chemical composition of the samples analysed were capsaicinoids Ghana Atomic Energy Commission for the purpose of removing and carotenoids. background microflora (Deng et  al., 2015). Samples were spread plated on selective media [Cefixime tellurite sorbitol MacConkey Capsaicinoids (CT-SMAC) Becton Dickinson Diagnostic Systems (BD) for E. coli; Capsaicinoids analysed in the samples were capsaicin and Palcam Listeria Selective (PLS) agar (BD) for L. monocytogenes and dihydrocapsaicin, which are the main capsaicinoids responsible for Xylose Lysine Deoxychocolate (XLD) for S. enterica Typhimurium] the hotness of chili pepper (Lu et al., 2017). under sterile conditions to confirm the sterility of the samples (Jeong et al., 2010; Deng et al., 2015). Ten grams of the samples from sterile pouches were weighed into sterile stomacher pouches (Seward, UK) Source of capsaicinoids and 90 ml of sterile buffered saline water was added. The samples Standards of the capsaicinoids were obtained from Extrasynthese that were irradiated were homogenized, serially diluted, spread (Lyon, France) and used for the study. Downloaded from https://academic.oup.com/fqs/article-abstract/3/4/265/5667890 by guest on 19 February 2020 Effect of gamma radiation and storage at 4°C Listeria monocytogenes, Escherichia coli, 2019, Vol. 3, No. 4 267 Extraction which was equipped with a revered phase column SunFire TM C (5 µm, 4.6 × 150 mm; Waters) thermostated at 30°C for both quali- Extraction of the capsaicinoids of interest was done according tative and quantitative analysis. Capsaicinoids were separated by an to the procedure of Barbero et  al. (2006). The pressurized liquid isocratic mixture of water: acetonitrile 55:44 v/v. Detection wave- extractor (Fluid Management Systems, USA) was used for the ex- length was set at 280 nm (Giuffrida et al., 2013). Calibration curves traction of the two main capsaicinoids. One gram of powdered of the standards were drawn using Microsoft Excel, 2010. Legon-18 pepper samples was weighed and contents extracted using accelerated solvent extractor equipped with a 100-ml stain- less steel extraction cells. Loaded cells with the pepper samples Total capsaicinoids and Scoville Heat Units mixed with inert sea sand which had been homogenized, were filled Total capsaicinoids and Scoville Heat Units (SHU) were computed with 90% ethanol to a pressure of 1500 psi. Heat was applied for according to the procedure of Aguiar et  al. (2016) and Jung et  al. the initial period of heat-up time; static extraction was effected (2015) and Orellana-Escobedo et  al. (2013), respectively. Total after all valves were closed. Contents of the cell were rinsed with capsaicinoids (TC) expressed as the extraction solvent and purged with N gas for 120 seconds. The TC  =  capsaicin + dihydrocapsaicin; and SHU were expressed extracts were collected from the cells after depressurization of the as SHU = [(% dihydrocapsaicin × 16.1) + (% capsaicin × 16.1)] × system (Barbero et al., 2006). 10,000 Carotenoids Quantification The main carotenoids analysed during the study were beta carotene Sample extracts were filtered through a 0.45-µm Millipore mem- and cryptoxanthin, capsanthin and zeaxanthin. brane filter and injected into an HPLC PDA (PerkinElmer Flexar), Table 1. Survival of E. coli after gamma irradiation and during storage at 4°C in powdered Legon-18 pepper (C. annuum). -1 Storage Microbial Count (log cfug ) Days 0 kGy 1 kGy 2 kGy 4 kGy 5 kGy Aa Ba Ca Da 0 6.69 ± 0.08 5.17 ± 0.11 4.59 ± 0.11 3.51 ± 0.11 ND Ab Bb Cb Db 2 6.43 ± 0.09 4.84 ± 0.11 4.24 ± 0.11 3.11 ± 0.11 ND Ac Bc Cc Dc 5 6.24 ± 0.08 4.44 ± 0.11 3.94 ± 0.11 2.81 ± 0.15 ND Ad Bd Cd Dd 12 5.67 ± 0.11 4.24 ± 0.11 3.66 ± 0.19 2.41 ± 0.15 ND Ae Bd Ce De 21 4.85 ± 0.09 4.07 ± 0.11 3.03 ± 0.09 2.11 ± 0.15 ND Af Ae Be Cf 30 3.53 ± 0.09 3.43 ± 0.09 2.87 ± 0.13 1.78 ± 0.12 ND 45 ND ND ND ND ND 60 ND ND ND ND ND Least Significant Difference: Means with the same letters (upper cases) in the same row are not significantly (P > 0.05) different from each other and means with the same letters in the same column (lower case, doses per day) are not significantly different (P > 0.05) from each other. Key: ND = not detected. Table 2. Stepwise regression analysis for the inactivation of E. coli in powdered Legon-18 pepper (C. annuum) stored at 4°C. Step Change Step (P value) Final (P value) R adjusted (%) 1 Add X 0.000* 0.000* 39.309 2 Add X 0.000* 0.000* 76.751 3 Add X *X 0.000* 0.000* 91.302 1 2 Key: X = storage days; X = doses (kGy) of gamma irradiation. 1 2 Table 3. Survival of S. Typhimurium after gamma irradiation and during storage at 4°C in powdered Legon-18 pepper (C. annuum). -1 Storage Days Microbial Count (log cfug ) 0 kGy 1 kGy 2 kGy 4 kGy 5 kGy Aa Ba Ca Da 0 6.49 ± 0.08 5.57 ± 0.11 5.37 ± 0.07 4.40 ± 0.09 ND Aa Ba Cb Db 2 6.38 ± 0.08 5.55 ± 0.11 5.18 ± 0.05 3.89 ± 0.08 ND Ab Bb Cc Dc 5 5.72 ± 0.11 5.32 ± 0.11 5.00 ± 0.11 3.65 ± 0.08 ND Abc Bc Cd Dd 12 5.62 ± 0.11 5.10 ± 0.11 4.80 ± 0.09 3.44 ± 0.08 ND Ac Bd Ce De 21 5.52 ± 0.11 4.90 ± 0.09 4.60 ± 0.09 3.02 ± 0.09 ND Ad Be Cf Df 30 5.12 ± 0.11 4.60 ± 0.09 3.65 ± 0.08 2.72 ± 0.11 ND Ad Bf Cg Dg 45 4.99 ± 0.11 3.79 ± 0.08 2.88 ± 0.11 1.46 ± 0.13 ND 60 4.65 ± 0.09 ND ND ND ND Least Significant Difference: Means with the same letters (upper cases) in the same row are not significantly (P > 0.05) different from each other and means with the same letters in the same column (lower case, doses per day) are not significantly different (P > 0.05) from each other. Key: ND = not detected. Downloaded from https://academic.oup.com/fqs/article-abstract/3/4/265/5667890 by guest on 19 February 2020 268 B. T. Odai et al., 2019, Vol. 3, No. 4 Source HPLC injection. Each carotenoid was chromatographically separ- ated by an AQUA 5u C 125A (150 × 4.60, 5 µm) reversed-phase Standards of beta carotene, capsanthin, zeaxanthin, and beta column with a gradient of acetone:water at the beginning 75:25. cryptoxanthin were obtained from Extrasynthese (Lyon, France). Microsoft Excel, 2010 was used to draw the calibration curves of the standards. Extraction One gram of the pepper samples was weighed and contents ex- Data analysis tracted using the accelerated solvent extractor equipped with 100-ml stainless steel extraction cells. The cells were loaded with the hom- StatGraphics Centurion XV.I.  and Least Significant Difference ogenized samples mixed with inert sea sand. The cells were filled (P < 0.05) were used to analyse the data obtained and means separ- with 90% ethanol to a pressure of 1500 psi. Heat was applied for ated, respectively. the initial period of heat-up time, after which static extraction took place after all the valves were closed. The cells were rinsed with the extraction solvent and purged with N gas for 2 minutes. Extracts Results and discussion from the cells were collected from the cells with 20 ml falcon tubes Gamma irradiation has been used for the decontamination of spices after depressurization of the system. and other foods. The effects of gamma irradiation on microorgan- isms in foods lead to the inactivation of such pathogens (Ban and Quantification Kang, 2014; Deng et al., 2015; Yu et al., 2017). The carotenoids studied were quantified using an HPLC (Topuz and Legon-18 pepper samples were contaminated with pathogens Odzemir, 2004). such as E. coli, L. monocytogenes, and S. Typhimurium and exposed Extracts from the samples were filtered through a 0.45-µm mem- to gamma irradiation at various doses to determine its effect on their brane filter (Millipore), into a glass vial (2  ml) and then used for inactivation. Table 4. Stepwise regression analysis for the inactivation of S. Typhimurium in powdered Legon-18 pepper (C. annuum) stored at 4°C. Step Change Step (P value) Final (P value) R Adjusted (%) 1 Add X 0.000* 0.000* 60.892 2 Add X 0.000* 0.000* 80.360 3 Add (X ) 0.000* 0.000* 82.376 4 Add (X ) 0.003* 0.003* 83.556 5 Add X *X 0.011* 0.011* 84.334 1 2 Key: X = storage days; X = doses (kGy) of gamma irradiation. 1 2 Table 5. Survival of L. monocytogenes after gamma irradiation and during storage at 4°C in powdered Legon-18 pepper (C. annuum). −1 Storage Microbial Count (log cfug ) Days 0 kGy 1 kGy 2 kGy 4 kGy 5 kGy Aa Ba Ca Da 0 6.26 ± 0.08 5.87 ± 0.11 4.97 ± 0.11 4.83 ± 0.12 ND Aa Bb Cb Db 2 6.15 ± 0.08 5.42 ± 0.11 4.46 ± 0.09 3.81 ± 0.11 ND Aa Bb Cc Dc 5 6.04 ± 0.08 5.28 ± 0.11 4.26 ± 0.09 3.12 ± 0.11 ND Ab Bc Cc Dd 12 5.78 ± 0.11 5.02 ± 0.11 4.10 ± 0.09 2.86 ± 0.11 ND Ac Bc Cd Dde 21 5.42 ± 0.11 4.90 ± 0.09 3.84 ± 0.09 2.66 ± 0.13 ND Ad Bd Ce De 30 5.18 ± 0.11 4.30 ± 0.09 3.15 ± 0.08 2.46 ± 0.13 ND Ad Be Cf Df 45 5.07 ± 0.11 3.19 ± 0.08 2.47 ± 0.11 1.96 ± 0.13 ND Ae Bf 60 4.85 ± 0.09 2.22 ± 0.11 ND ND ND Least Significant Difference: Means with the same letters (upper cases) in the same row are not significantly (P > 0.05) different from each other and means with the same letters in the same column (lower case, doses per day) are not significantly different (P > 0.05) from each other. Key: ND = not detected. Table 6. Stepwise regression analysis for the inactivation of L. monocytogenes in powdered Legon-18 pepper (C. annuum) stored at 4°C. Step Change Step (P value) Final (P value) R Adjusted (%) 1 Add X 0.000* 0.000* 68.864 2 Add X 0.000* 0.000* 84.500 3 Add (X ) 0.011 0.011* 85.223 4 Add X *X 0.053** 0.053** 85.579 2 2 Key: X = storage days; X = doses (kGy) of gamma irradiation. 1 2 Downloaded from https://academic.oup.com/fqs/article-abstract/3/4/265/5667890 by guest on 19 February 2020 Effect of gamma radiation and storage at 4°C Listeria monocytogenes, Escherichia coli, 2019, Vol. 3, No. 4 269 Sterility of samples There was no detection of the pathogens after the samples were ex- posed to sterility dose. This observation was similar to the study of Deng et al. (2015). Inactivation of E. coli Table 1 indicates the effect of gamma irradiation on the survival of E.  coli after exposure to gamma irradiation. There was a general reduction in the count (log cfu/g) of E.  coli in the pepper samples at all the doses of gamma irradiation in the pepper samples during the period of study (P  <  0.05). Inactivation of the pathogen was dose-dependent which is similar to the observations of Deng et  al. (2015), Waje et al. (2008), Ban and Kang (2014), Carcel et al., 2015, and Jeong and Kang (2017). This observation may be attributed to the inability of the pathogen to recover from the injuries caused by gamma irradiation, the inability of the injured cells to adopt to their environment (Wu et al., 2008). A stepwise regression analysis (Table 2) was used to determine the effect of gamma irradiation and storage (P < 0.05; R  = 91.52% or 0.9152) on the inactivation of E. coli. A model computed from the regression analysis is indicated as Inactivation of E. coli (log cfu/g)= 6.021 − 0.1078 X1 − 1.1255 X2 + 0.0200 X1 ∗ X2 (1) Where X = storage days X = doses (kGy) of gamma irradiation Inactivation of S. Typhimurium Inactivation of S. Typhimurium is indicated in Table 3. A reduction in the microbial load (log cfu/g) was observed (P < 0.05) from the first day to the end of the study. Gamma irradiation and storage affected the microbial count (P  <  0.05; Table 4) of the pathogen. Jeong and Kang (2017) and Ban and Kang (2014) had indicated the effect of gamma irradiation on the inactivation of S. Typhimurium which was dose dependent. In this study, a dose-dependent effect was observed. This observation may be due to the production of free radicals, reactive oxygen species, and other products from gamma irradiation which might have interacted with cellular composition, leading to inactivation (Yong et  al., 2015). There was no detection at 5 kGy. The effect of gamma irradiation and storage on the inactivation of S. Typhimurium was determined using the stepwise regression (Table 4) analysis (P < 0.05; R  = 0.8500 or 85.00%). The model (2) expressed the inactivation of the pathogen. Inactivation of S. Typhimurium (log cfu/g)= 6.294 − 0.0196X −0.379X − 0.0001(X )(2) 2 1 −0.1375(X ) + 0.0056X ∗ X 2 1 2 Inactivation of L. monocytogenes The microbial count of the L. monocytogenes in the samples ranged from no detection to about 6 log cfu/g (Table 5). A  general reduc- tion in the count of L. monocytogenes in the pepper samples from the onset to the end of the study. There was a dose-dependent effect of gamma irradiation on the inactivation of the pathogen is similar to literature (Rico et  al., 2010; Mukhopadhyay et  al., 2013; Jeong and Kang, 2017). Inactivation was completely achieved at a dose of 5 kGy (no detection). Jeong and Kang (2017) and Waje et al. (2008) had indicated the effect of gamma irradiation on the inactivation Table 7. Effect of gamma irradiation and storage on some quality parameters of Legon-18 pepper (C. annuum) powder at 4°C. Storage Capsaicin (mg/100 g) Dihydrocapsaicin (mg/100 g) Total capsaicinoids (mg/100 g) SHU (×10,000) Weeks 0 kGy 5 kGy 0 kGy 5 kGy 0 kGy 5 kGy 0 kGy 5 kGy Ia Hb Ga Hb Ia Ib Ia Ib 0 178.74 ± 1.30 221.00 ± 2.29 77.12 ± 1.84 88.48 ± 1.11 255.87 ± 2.57 309.47 ± 3.32 4119.46 ± 41.33 4982.51 ± 53.49 Ha Hb Fa Hb Ha Hb Ha Hb 1 177.18 ± 0.28 217.35 ± 0.37 75.48 ± 0.02 88.76 ± 0.04 252.65 ± 0.39 306.12 ± 0.36 4067.74 ± 62.26 4928.46 ± 57.45 Ga Gb Ea Gb Ga Gb Ga Gb 2 173.25 ± 0.00 216.88 ± 0.11 74.29 ± 0.05 87.21 ± 0.00 247.54 ± 0.30 304.09 ± 0.11 3985.45 ± 36.96 4865.9118.19 Fa Fb Ea Fb Fa Fb Fa Fb 3 165.73 ± 0.77 213.72 ± 0.17 73.35 ± 0.12 86.38 ± 0.37 239.08 ± 1.06 300.10 ± 0.47 3849.15 ± 17.01 4831.62 ± 76.45 Ea Eb Da Eb Ea Eb Ea Eb 4 161.51 ± 0.15 210.53 ± 0.00 66.15 ± 0.00 85.32 ± 0.15 227.66 ± 0.21 295.85 ± 0.15 3665.39 ± 33.07 4763.26 ± 23.72 Da Db Ca Db Da Db Da Db 5 154.40 ± 1.22 207.31 ± 0.39 64.46 ± 0.63 83.56 ± 0.51 218.86 ± 1.14 290.86 ± 0.20 3523.64 ± 18.43 4682.88 ± 32.45 Ca Cb Ca Cb Ca Cb Ca Cb 6 146.93 ± 0.00 204.44 ± 0.73 63.82 ± 0.58 82.62 ± 0.39 210.75 ± 0.76 287.06 ± 0.34 3393.05 ± 12.30 4621.74 ± 54.33 Ba Bb Ba Bb Ba Bb Ba Bb 7 144.74 ± 0.00 198.95 ± 0.09 61.97 ± 0.00 80.84 ± 0.10 206.70 ± 0.05 279.79 ± 0.17 3327.91 ± 0.78 4504.64 ± 27.11 Aa Ab Aa Ab Aa Ab Aa Ab 8 140.34 ± 0.00 190.57 ± 0.11 59.80 ± 0.15 80.05 ± 0.18 200.14 ± 0.42 270.61 ± 0.14 3222.23 ± 67.96 4356.87 ± 22.17 Least Significant Difference: Means with the same letters (upper case, within the same column) are not significantly (P > 0.05) different from each other and means with the same letters in the same row (lower case, doses within a particular week) are not significantly different (P > 0.05) from each other. Downloaded from https://academic.oup.com/fqs/article-abstract/3/4/265/5667890 by guest on 19 February 2020 270 B. T. Odai et al., 2019, Vol. 3, No. 4 Table 8. Effect of gamma irradiation and storage on some carotenoids in Legon-18 pepper (C. annuum) powder at 4 C. Storage Capsanthin (mg/100 g) Beta carotene (mg/100 g) Beta cryptoxanthin (mg/100 g) weeks 0 kGy 5 kGy 0 kGy 5 kGy 0 kGy 5 kGy Fb Ga Ib Ia Hb Da 0 1.48 ± 0.00 1.36 ± 0.02 10.27 ± 0.00 9.38 ± 0.00 2.11 ± 0.02 1.55 ± 0.01 Eb Ga Hb Ha Gb Da 1 1.46 ± 0.01 1.35 ± 0.01 10.04 ± 0.00 9.24 ± 0.00 2.05 ± 0.00 1.59 ± 0.00 Db GFa Gb Ga Gb Da 2 1.42 ± 0.00 1.33 ± 0.00 9.92 ± 0.00 8.78 ± 0.00 2.03 ± 0.02 1.56 ± 0.03 Db EFa Fb Fa Fb Ca 3 1.41 ± 0.00 1.30 ± 0.00 9.43 ± 0.00 8.48 ± 0.00 1.95 ± 0.00 1.48 ± 0.01 Db DEa Eb Ea Eb BCa 4 1.41 ± 0.00 1.27 ± 0.00 9.20 ± 0.00 8.23 ± 0.02 1.87 ± 0.00 1.43 ± 0.02 Db DCa Db Da Db Ba 5 1.41 ± 0.00 1.26 ± 0.00 8.91 ± 0.02 8.21 ± 0.00 1.80 ± 0.01 1.40 ± 0.00 Cb Ca Cb a Cb Aa 6 1.38 ± 0.02 1.23 ± 0.00 8.69 ± 0.07 7.91 ± 0.00C 1.71 ± 0.00 1.30 ± 0.00 Bb Ba Bb Ba Bb Aa 7 1.35 ± 0.02 1.20 ± 0.00 8.48 ± 0.00 7.26 ± 0.00 1.66 ± 0.00 1.24 ± 0.00 Ab Aa Ab Aa Ab Aa 8 1.32 ± 0.02 1.14 ± 0.04 8.17 ± 0.00 6.01 ± 0.00 1.50 ± 0.03 1.24 ± 0.11 Least Significant Difference: Means with the same letters (upper case, within the same column) are not significantly (P > 0.05) different from each other and means with the same letters in the same row (lower case, doses within a particular week) are not significantly different (P > 0.05) from each other. of L.  monocytogenes. The observed pattern is similar to the obser- Effect of gamma irradiation on carotenoids during storage vation of Yu et al. (2017), Jeong and Kang (2017), and Waje et al. The carotenoids in the pepper samples analysed were capsanthin, (2008). The irradiation effects might have led to injuries to cells as beta carotene, beta cryptoxanthin, and zeaxanthin. Zeaxanthin was well as the effects of gamma irradiation on the cellular components below the detection point hence no data on this. The other carot- (Yong et al., 2015). enoid contents (Table 8) reduced after exposure to gamma irradi- A significant effect (P < 0.05) of gamma irradiation and storage ation at 5 kGy as compared to the contents of the samples that were was observed from the stepwise regression analysis (Table 6), which not irradiated (P < 0.05). Gamma irradiation at 5kGy caused losses had an R  = 86.07% or 0.8607. 8.11%, 8.67%, and 26.54% in capsanthin, beta carotene, and beta Model (3) from the regression analysis for the inactivation is cryptoxanthin, respectively in the pepper samples as compared with expressed as the unirradiated samples. There was a general reduction in the ca- rotenoid content during storage (P < 0.05). These observations have been reported elsewhere in literature (Pérez-Gálvez and Mínguez- Inactivation of Mosquera, 2001; Topuz and Ozemir, 2003; Kim et  al., 2004; Kim L.monocytogenes (log cfu/g)= 6.470 − 0.0514X − 0.645X 1 2 et al., 2006; Rico et al., 2010; Giuffrida et al., 2014; Guadarrama- −0.0820(X ) + 0.0039X ∗ X 2 1 2 Lezama et  al., 2014; Jung et  al., 2015). The reduced content after irradiation and during storage may due to the secondary effects Where X = storage days of gamma irradiation, component oxidation, form of the milled X = doses (kGy) of gamma irradiation sun-dried pepper samples, and the structure of the carotenoids. Chemical composition Conclusions Effect of gamma irradiation on capsaicinoids during storage Gamma irradiation and storage had significant effect (P  <  0.05) The capsaicinoids analysed in the study were capsaicin and on the inactivation and quality parameters determined in Legon- dihydrocapsaicin (Table 7). Total capsaicinoids and SHU were 18 pepper powder. Gamma irradiation can be used for the decon- computed as described earlier. Samples that were irradiated at 5 tamination of pathogens such E.  coli, L.  monocytogenes, and S. kGy had higher values as compared to the samples that were not ir- Typhimurium in Legon-18 pepper powder. A  dose of 5 kGy can radiated. Samples irradiated at 5 kGy recorded percentage increase inactivate all the pathogens immediately after exposure to gamma of 23.64%, 14.7%, and 20.95% in capsaicin, dihydrocapsaicin, irradiation, not withstanding, doses such as 2 and 4 kGy can also and total capsaicinoids, respectively as compared with the control. be used for the inactivation of the pathogens used in the study but There was a general reduction in the capsaicinoid content of the subject to storage time of 60 days. E. coli could be inactivated at a samples during storage. Since TC and SHU were computed from dose of 1 kGy at day 30. Samples irradiated had lower carotenoid the capsaicinoids analysed, similar patterns of were observed. contents as compared to the unirradiated. Zeaxanthin was below the Giuffrida et  al. (2014), Yu et  al. (2017), and Topuz and Odzemir detection limit. Higher values of hotness indices were observed in the (2004) in a previous indicated that gamma and storage caused a re- irradiated but not in the unirradiated samples. duction in the content of capsaicinoids, however, Byun et al. (1996) and Lee et al. (2004) indicated the stability of capsaicinoids below 15kGy. The observed higher contents in the samples irradiated Acknowledgements are similar to the observations of Giuffrida et al. (2014), Yu et al. Our profound gratitude goes to the technologists at the Department of (2017), and Topuz and Odzemir (2004) and this may be attributed Bacteriology, Noguchi Memorial Institute for Medical Research, University to the induction of water deficit by gamma irradiation (Farkas, of Ghana, Legon, Accra-Ghana for the assistance rendered during the micro- 2006). The general reduction in the capsaicinoids, TC, and SHU biology aspect, the Radiation Technology Centre (BNARI-GAEC) for carrying during storage may be due to the effect of milling and residue en- out dosimetry for dose delivery and Central Laboratory of KNUST for the zymatic action (Wang et al., 2009). analysis of capsaicinoids and carotenoids in the samples. Downloaded from https://academic.oup.com/fqs/article-abstract/3/4/265/5667890 by guest on 19 February 2020 Effect of gamma radiation and storage at 4°C Listeria monocytogenes, Escherichia coli, 2019, Vol. 3, No. 4 271 Giuffrida,  D., Dugo,  P., Torre,  G., Bignardi,  C., Cavazza,  A., Corrandi,  C., Funding Dugo,  G. (2013). Characterization of 12 Capsicum varieties by evalu- Funds were obtained from the authors from the collection of data, its analysis, ation of their carotenoid and pungency determination. Food Chemistry, and interpretation. 140:794–802. Giuffrida,  D., Dugo,  P., Torre,  G., Bignardi,  C., Cavazza,  A., Corrandi,  C., Dugo,  G. (2014). Evaluation of carotenoid and capsaicinoid and Conflict of interest capsaicinoid contents in powder of red chili peppers during one year of Authors hereby certify that there are no conflicts of interest with any organ- storage. Food Research International, 65: 163–170. ization, financial, or other regarding the material discussed in the manuscript Gregoire,  O., Cleland,  M.  R., Mittendorfer,  J., Dababneh,  S., Ehlermann,  D.  A.  E., Fan,  X., et  al. (2003). Radiological safety of food irradiation with high energy X-rays: theoretical expectations and experi- References mental evidence. Radiation Physics and Chemistry, 67: 169–183. Aguiar, A. C., Silva, L. P. S., de Rezende, C. A., Barbero, G. F., Martinez, J. Guadarrama-Lezama,  A.  Y., Jaramillo-Flores,  E., Gutierrez-Lopez,  G.  F., (2016). Encapsulation of pepper oleoresin by supercritical fluid extraction Perez-Alonso,  C., Dornates-Alvarez,  L., Alamilla-Beltran,  L. (2014). Ef- of emulsions. The Journal of Supercritical Fluids, 112:37–43. fects of storage temperature and water activity on the degradation of Ali, M. (ed.). (2006). Chilli (Capsicum spp) Food Chain Analysis: Setting Re- carotenoids contained in microencapsulated chili extract. Drying Tech- search Priorities in Asia. AVRDC-The World Vegetable Centre, Technical nology, 32:1435–1447. Bulletin No. 38, AVRDC Publication, Shanhua, Taiwan, pp. 1–253. Jeong, A-R., Jo, M. J., Koo, M., Ku, K-H., Park, J-B., Kim, H. J. (2010). Micro- Almela, L., Nieto-Sandoval, J. M., Fernández López, J. A. (2002). Microbial bial contamination of fresh-red pepper and packaged-red pepper powder inactivation of paprika by a high-temperature short-X time treatment. In- in South Korea. Journal of Food Science and Nutrition, 15:233–238. fluence on color properties. Journal of Agricultural and Food Chemistry, Jeong,  S-G., Kang,  D-H. (2017). Inactivation of Escherichia coli O157:H7, 50: 1435–1440. Salmonella Typhimurium, and Listeria monocytogenes in ready-to-bake Ban, G. H., Kang, D. H. (2014). Effects of gamma irradiation for inactivating cookie dough by gamma and electron beam irradiation. Food Micro- Salmonella Typhimurium in peanut butter product during storage. Inter- biology, 64:172–176. national Journal of Food Microbiology, 171: 48–53. Jung, K., Song, B-S., Kim, M. J., Moon, B-G., Go, S-M., Kim, J-K., Lee, Y-J., Barbero, G. F., Palma, M., Barroso, C. G. (2006). Pressurized liquid extraction Park, J-H. (2015). Effect of X-ray, gamma ray, and electron beam irradi- of capsaicinoids from peppers. Journal of Agricultural and Food Chem- ation on the hygienic and physicochemical qualities of red pepper powder. istry, 54: 3231–3236. LWT-Food Science and Technology, 63:846–851. Bhunia,  A.  K. (2018). Foodborne Microbial Pathogens. Mechanisms and Kahraman,  T., Ozmen,  G. (2009). Quality of selected spices and herbs con- Pathogenesis. Springer Science+Business Media, LLC, New York, USA, pp. sumed in Turkey. Archiv für Lebensmittel hygiene, 60:185–191. 12–22. Kim, S., Lee, K. W., Park, J., Lee, J., Hwang I. K. (2006). Effect of drying in Boer, E. D., Spiegelenberg, W., Jansen, F. (1985). Microbiology of Spices and antioxidant activity and changes of ascorbic acid and colour by different herbs. Antonie van Leeuwenhoek, 51:435–438. drying and storage in Korean red pepper (Capsicum annuum L.). Inter- Buckenhuskes,  H.  J., Rendlen,  M. (2004). Hygienic problems of phytogenic national Journal of Food Science and Technology, 41:90–95. raw material for food production with special emphasis on herbs and Kim, S., Park, J. B. and Hwang, I. K. (2004). Composition of main carotenoids spices. Food Science and Biotechnology, 13:262–268. in Korean red pepper (Capsicum annuum, L.) and the changes of pig- Byun, M. W., Yook, H. S., Kwon, J. H., Kim, J. O. (1996). Improvement of ment stability during drying and storage process. Journal of Food Science, hygiene quality and long-term storage of dried red pepper by gamma- 69:FCT39–44. irradiation. Korean Society of Food Science and Technology, 28: 482–489. Lee,  J.  H., Sung,  T.  H., Lee,  K.  T., Kim,  M.  R. (2004). Effect of gamma- Carcel,  J.  A., Benedito,  J., Cambero,  M.  I., Cabeza,  M.  C., Ordonez,  J.  A. irradiation on colour, pungency and volatiles of Korean red pepper (2015). Modelling and optimization of the E-beam treatment of chicken powder. Journal of Food Science, 69:C585–C5591. steaks and hamburgers, considering food safety, shelf-life and sensory Lilie, M., Hein, S., Wilhelm, P., Müller, U. (2007). Decontamination of spices quality. Food and Bioproducts Processing, 96:133–144. by combining mechanical and thermal effects – an alternative approach Cheon, H-L., Shin, J-S., Park, K-H., Chung, M-S., Kang, D-H. (2015). Inacti- for quality retention. International Journal of Food Science and Tech- vation of pathogens in red pepper powder (Capsicum annuum L.) using nology, 42:190–193. combined UV-C irradiation and mild heat. Food Control, 50:441–445. Liu,  W.  Y., Kang,  W-H., Kang,  B-C. (2013). Basic information o pepper. In: Deng,  W., Wu,  G., Guo,  L., Long,  M., Li,  B., Liu,  S., Cheng,  L., Pan,  X., Genetics, Genomics and Breeding of Peppers and Eggplants. Kang, B-C., Zou, L. (2015). Effect of gamma irradiation on Escherichia coli, Salmon- Kole,  C. (eds.) CRC Press. Taylor and Francis group. LLC, Boca Raton, ella Enterica Typhimurium and Aspergillus niger in peppers. Food Science pp. 1–13. and Technology Research, 21: 241–245. Lu, M., Ho, C. T., Huang, Q. (2017). Extraction, bioavailability, and bioefficacy Department of Health, State Government of Victoria, Australia (DOH/Vic- of capsaicinoids. Journal of Food and Drug Analysis, 25: 27–36. toria/AU). 2010. Report on a survey of spices for the presence of patho- Ministry of Food and Agriculture (MOFA). (2007). Chilli Pepper Production gens - 2007. http://www.health.vic.gov.au/archive/archive2011/foodsafety/ Guide. Horticulture Export Industry Initiative, MOFA, Accra-Ghana, pp. 9. archive/microbiological.htm. Accessed 26 September 2017. Mukhopadhyay, S., Ukuku, D., Fan, X., Juneja, V. K. (2013). Efficacy of in- Doku,  S.  K. (2015). Genetic diversity studies. In: Twenty Accessions of Hot tegrated treatment of UV light and low-dose gamma irradiation on in- Pepper (Capsicum Spp L.) In Ghana. A thesis presented to the Department activation of Escherichia coli O157:H7 and Salmonella enterica on grape of Nuclear Agriculture and Radiation Processing School of Nuclear and tomatoes. Journal of Food Science, 78: M1049–M1056. Allied Sciences University of Ghana, Kwabenya-Accra, Ghana. Ochoa-Alejo,  N., Ramirez-Malagon,  R. 2001. Invited review: in vitro chilli Ducic, M., Klisara, N., Markov, S., Blagojevic, B., Vidakovic, A. (2016). The pepper biotechnology. In Vitro Cellular and Developmental Biology-Plant, fate and pasteurization of-based inactivation of Escherichia coli O157, 37:701–729. Salmonella Typhimurium and Listeria monocytogenes in dry, fermented Orellana-Escobedo,  L., Garcia-Amezquita,  L.E., Olivas,  G.  I., Ornelas- sausages. Food Control, 59:400–406. Paz, J. J., Sepulveda, D. R. (2013). Capsaicinoids content and proximate Farkas, J. (2006). Irradiation for better foods. Trends in Food Science Tech- composition of Mexican chili peppers (Capsicum spp.) cultivated in the nology, 17:148–152. State of Chihuahua. CytA-Journal of Food, 11: 179–184. Farkas,  J., Andrassy,  E. (1988). Comparative analysis of spices decontamin- Pérez-Gálvez, A., Mínguez-Mosquera, M. I. (2001). Structure-reactivity re- ated by ethylene oxide or gamma-radiation. Acta Alimentaria, 17: 77–94. lationship in the oxidation of carotenoid pigments of the pepper (Cap- Downloaded from https://academic.oup.com/fqs/article-abstract/3/4/265/5667890 by guest on 19 February 2020 272 B. T. Odai et al., 2019, Vol. 3, No. 4 sicum annuum L.). Journal of Agricultural and Food Chemistry, 49: Topuz, A., Ozdemir, F. (2003). Influences of gamma-irradiation and storage on 4864–4869. the carotenoids of sun-dried and dehydrated paprika. Journal of Agricul- Piggott, J., Othman, Z. (1993). Effect of irradiation on volatile oils of black tural and Food Chemistry, 51: 4972–4977. pepper. Food Chemistry, 46:115–119. Waje,  C.  K., Kim,  H.  K., Kim,  K.  S., Todoriki,  S., Kwon,  J.  H. (2008). Pinto, C. M. F., dos Santos, I. C., de Araujo, F. F., da Silva, T. P. (2016). Pepper Physicochemical and microbiological qualities of steamed and irradiated importance and growth. In: do Rêgo, E. R., do Rêgo, M. M., Finger, F. L, ground black pepper (Piper nigrum L.). Journal of Agricultural and Food eds. Production and Breeding of Chilli Peppers (Capsicum spp.). Springer Chemistry, 56: 4592–4596. International Publishing, Switzerland, pp. 503–545. Wang,  Y., Xia,  Y, Wang,  J., Luo,  F., Huang,  Y. (2009). Carotenoids in chili Rico, C. W., Kim, G-R., Ahn, J-J., Kim, H-K., Furuta, M., Kwon, J-H. (2010). pepper (Capsicum annuum, L.) powder as affected by heating and storage The comparative effect of steaming and irradiation on the physicochemical methods. American Society of Agricultural and Biological Engineers, 52: and microbiological properties of dried red pepper (Capsicum annum L.). 2007–2010. Food Chemistry, 119: 1012–1016. WHO. (1981). Wholesomeness of Irradiated Food. Report of a Joint FAO/ Rufino, J. L. S., Penteado, D. C. S. (2006) Importância econômica, perspectivas IAEA/WHO Expert Committee, Technical Report Series 659. World e potencialidades do Mercado para pimenta. Informe Agropecuário, Belo Health Organization, Geneva, Switzerland. p. 33. Horizonte 27:7–15 Witkowska, A. M., Hickey, D. K., Alonso-Gomez, M., Wilkinson, M. G. (2011). Schweiggert, U., Carle, R., Schieber. A., (2007). Conventional and alternative The microbiological quality of commercial herb and spice preparations used processes for spice production-a review. Trends in Food Science and Tech- in the formulation of a chicken supreme ready meal and microbial survival nology, 18: 260–268. following a simulated industrial heating process. Food Control, 22: 616–625. Sualihu,  A. (2012). Effect of Three Pre-Drying Treatments and Two Drying Wu, V. C. (2008). A review of microbial injury and recovery methods in food. Methods on the Quality of Scotch Bonnet (capsicum chinense) Grown in Food Microbiology, 25: 735–744. the Tolon/Kumbungu District of Northern Ghana. A thesis submitted to Yong,  H.  I., Kim,  H-J., Nam,  K.  C., Kwon,  J.  H., Jo,  C. (2015). Radiation Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. sensitivity of foodborne pathogens in meat byproducts with different Tainter,  D.  R., Grenis,  A.  T. (2001). Spices and Seasonings—A Food Tech- packaging. Radiation Physics and Chemistry, 115: 155–157. nology Handbook. 2nd edn. VCH, New York Wiley. Yu, W-J., Liu, H-P., Zhang, X-W., Dong, D., Jiang, Y., Sun, N-X., Liu, Y-K., Topuz,  A., Odzemir,  F. (2004). Influences of gamma irradiation and storage Yuan, J-F. (2017). Postirradiation changes of the microbiological quality, on the carotenoids of sun-dried and dehydrated paprika. Food Chemistry, aflatoxin, capsaicinoids, volatile oils, and the color of red pepper powder. 86: 509–515. Journal of Food Processing and Preservation, 1352:1–9.

Journal

Food Quality and SafetyOxford University Press

Published: Dec 31, 2019

There are no references for this article.