Optimization of emulsification procedure for mutual maximizing the encapsulation and exergy efficiencies of fish oil microencapsulation Mortaza Aghbashlo a, ⁎, Hossien Mobli a , Shahin Rafiee a , Ashkan Madadlou b a Faculty of Agricultural Engineering and Technology, University of Tehran, Karaj, Iran b Department of Food Technology, Institute of Chemical Technologies, Iranian Research Organization for Science & Technology (IROST), Tehran, Iran abstract article info Article history: Received 8 December 2011 Received in revised form 16 March 2012 Accepted 24 March 2012 Available online 16 April 2012 Keywords: Fish oil microencapsulation Emulsion preparation Encapsulation efficiency Exergy efficiency Spray drying The aim of this work was to study the influence of emulsion characteristics on exergy efficiency and quality of fish oil microencapsulated within skim milk powder (SMP) by spray drying. Response surface method (RSM) and genetic algorithm (GA) were applied to optimize the emulsion preparation procedure for production of fish oil microcapsule. The proposed emulsions were prepared, according to a central composite design and the feeds were dried using a mini spray dryer. Independent variables were: aqueous phase content, oil pro- portion in total solids, and emulsification time. The encapsulation efficiency and exergy efficiency were con- sidered as dependent variables. The RSM was used to build the mathematical equations and created models were integrated by applying three approaches to determine the fitness value of GA. Finally, the optimal emul- sion preparation procedure was determined to simultaneously obtain the highest values for both encapsula- tion efficiency and exergy efficiency. The results of authentication test for selected emulsion procedure preparation demonstrated the ability of applied approach for designation of sustainable and qualified process in fish oil microencapsulation by spray drying. © 2012 Elsevier B.V. All rights reserved. 1. Introduction It is well established that omega-3 polyunsaturated fatty acids (PUFAs), especially docosahexaenoic acid (DHA) from sea fish are es- sential nutrients for human's growth and health [1]. However, fortifi- cation of foods with these nutraceuticals is confined because of extreme sensitivity of PUFA to oxidation and consequent formation of toxic hydroperoxides during the manufacture and storage [2]. Encapsulation of PUFA within microcarriers has appeared as a useful technology to retard the oxidation by minimizing the access of unde- sirable factors e.g. oxygen, light and moisture to the surrounded oil [1]. Microencapsulation is defined as the process of enveloping a solid, liquid or gaseous substance within another substance in very small sealed capsule from which, core material is gradually diffused through the capsule walls at controlled rates under specific condi- tions [3,4]. Microencapsulation is advantageous due to the improve- ment of handling properties of sticky materials, preservation of the taste or odor of the core, control of the release rate of core material and dilution of the core when it should be used in only very small amounts, etc. [5,6]. Among the different techniques developed to encapsulate food ingredients such as physical methods (e.g. pan coat- ing, air-suspension coating, centrifugal extrusion, vibration nozzle and spray drying) and chemical methods (e.g. interfacial polymerization, in-situ polymerization, and matrix polymerization), the most common technique applied in this field is spray-drying because it is rather inex- pensive and straightforward [2,6]. Low energy efficiency of the process and relatively low oil encapsulation efficiency are among the most important challenges encountered in a spray drying process. These may arise from either improper drying conditions or inappropriate feed preparation and formulation. Exergy analysis by using the conservation of mass and conserva- tion of energy principles together with the second law of thermo- dynamics has been extensively applied for the analysis, design, improvement, and optimization of thermal systems during the past few decades. From thermodynamics point of view, exergy is defined as the maximum amount of work, which can be produced by a sys- tem, or a flow of matter or energy as it comes to equilibrium with a reference environment [7,8]. Therefore, it seems that applying the exergy analysis for food processing operations may be a useful tech- nique to enhance the sustainability of these operations. However, increasing the sustainability of a process may negatively influence the quality of product. An approach in which the process sustainabil- ity and final product quality is considered simultaneously, is therefore needed to optimize the fish oil microencapsulation process via spray drying. Recently, Erbay and Icier [9,10] optimized the drying of olive leaves in hot air and heat pump dryers by taking into account the exergy efficiency of dryers and quality of dried product using response surface method (RSM). A similar approach via integrating the exergy efficiency of process with quality indices of generated Powder Technology 225 (2012) 107–117 ⁎ Corresponding author. Tel.: + 98 261 2801011; fax: + 98 261 2808138. E-mail address: mortazaaghbashlo@yahoo.com (M. Aghbashlo). 0032-5910/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.powtec.2012.03.040 Contents lists available at SciVerse ScienceDirect Powder Technology journal homepage: www.elsevier.com/locate/powtec