The inﬂuence of drying methods on the stabilization of ﬁsh oil microcapsules:
Comparison of spray granulation, spray drying, and freeze drying
Sri Haryani Anwar
, Benno Kunz
IEL Food Technology and Biotechnology, Department of Nutrition and Food Sciences, University of Bonn, Roemerstrasse 164, 53117 Bonn, Germany
Jurusan Teknologi Hasil Pertanian, Fakultas Pertanian, Universitas Syiah Kuala, Banda Aceh 23111, Indonesia
Received 16 January 2011
Received in revised form 20 February 2011
Accepted 23 February 2011
Available online 1 March 2011
The stability of microencapsulated ﬁsh oil prepared using various drying methods is investigated. The ﬁsh
oil with ratio of 33/22, eicosapentaenoic acid (EPA):docosahexaenoic acid (DHA), is emulsiﬁed with four
combinations of matrices, and emulsions are dried by spray granulation (SG), spray drying (SD), and
freeze drying (FD) to produce 25% oil powders. The objective is to identify the most critical factors to
determine powder stability and to further examine the superiority of the SG process compared to other
drying processes. The stability is examined by measurement of peroxide values (PV) and GC-headspace
propanal after 8-week’s storage at room temperature (±21 °C)
The best matrices are a combination of 10% soybean soluble polysaccharide (SSPS) and 65% octenyl suc-
cinic anhydride (OSA-starch). Microencapsulation of 620 mg/g omegaÀ3 ﬁsh oil with these matrices then
dried by SG is able to produce powder having a very low propanal content and with a shelf life of 5 weeks
at ±21 °C. The results indicate that microcapsules produced by SG are actually formed ﬁrstly by agglom-
eration of seed particles. These agglomerated particles are then covered by successive layers. The particle
enlargement is determined by mechanism of the layer growth. Therefore, the SG process produces ‘‘mul-
tiple encapsulations’’ granules which provide maximum protection to the oil droplets.
Comparison of the SG, SD, and FD processes conﬁrms that combination of matrices, drying temperature,
microcapsule morphology, and processing time are among the most critical factors governing stability.
Exposure to heat is proved to be a limiting factor for drying unstable emulsion.
Ó 2011 Elsevier Ltd. All rights reserved.
Selection of the best coating materials and microencapsulation
process are crucial steps in food microencapsulation. Previous
works have underlined that the best way to emulsify ﬁsh oil is to
combine coating materials that function as a carrier matrix and
as an emulsiﬁer (Sheu and Rosenberg, 1998). Literature review
indicates that even the best combination of biopolymers for mic-
roencapsulating ﬁsh oil used with different drying techniques
can produce both stable and unstable products. It is necessary to
determine which combinations are the best for microencapsulat-
ing the right amount of polyunsaturated fatty acids (PUFAs) in ﬁsh
In an earlier publication, Anwar et al. (2010), underline that
spray granulation (SG) is a good method to produce ﬁsh oil pow-
der. SG offers low drying temperature (max. 70 °C) to dry an emul-
sion and this method is suitable for microcapsule production
containing sensitive cores such as ﬁsh oil. To date, there are data
gaps in the ﬁeld of ﬁsh oil microencapsulation that need to be
ﬁlled. There are no studies where various production methods
are compared especially to evaluate SG in comparison with other
drying techniques, i.e., spray drying (SD), and freeze drying (FD).
Previous research usually investigated microencapsulation by a
commonly used method such as spray drying or only by freeze
drying. Unsatisﬁed outcomes obtained by a certain method might
be different if produced by other processes. Each drying method
offers advantages and disadvantages and so does each coating
material. By carefully examining these two factors, this research
is designed to answer the questions associated with the stability
of ﬁsh oil microcapsules against oxidation in relation to how they
0260-8774/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
Abbreviations: SG, spray granulation; SD, spray drying; FD, freeze drying; EPA,
eicosapentaenoic acid; DHA, docosahexaenoic acid; PUFAs, polyunsaturated fatty
acids; SSPS, soybean soluble polysaccharide; OSA-starch, octenyl succinic anhy-
drate-starch; HPBCD, hydroxypropyl betacyclodextrin; PV, peroxide value; GC-
headspace, gas chromatography-headspace; SEM, scanning electron microscope;
FEG-SEM, ﬁeld emission gun-scanning electron microscope; MC-1, matrix combi-
nation-1; MC-2, matrix combination-2; MC-3, matrix combination-3; MC-4, matrix
combination-4; ME, microencapsulation efﬁciency.
Corresponding author at: IEL Food Technology and Biotechnology, Department
of Nutrition and Food Sciences, University of Bonn, Roemerstrasse 164, 53117 Bonn,
Germany. Tel.: +49 (0)228 734459; fax: +49 (0)228 734429.
E-mail addresses: firstname.lastname@example.org, email@example.com (S.H. Anwar).
Journal of Food Engineering 105 (2011) 367–378
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Journal of Food Engineering
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