Investigation of effects of different wall materials and emulsification applications on microencapsulation of flaxseed oil by spray drying

In this study, flaxseed oil an important source of omega-3 fatty acids, was microencapsulated using different wall materials and emulsification methods. On this purpose, flaxseed oil was microencapsulated by using three carbohydrate derivatives (maltodextrine, N-Lok, HiCap 100), two proteins (sodium caseinate, whey protein concentrate) and gum arabic in triple combinations determined by mixture design and optimal ratio of each components which provided the maximum microencapsulation efficiency was calculated for each combinations. Effects of different emulsification methods (classical and ultrasonic homogenization) on microencapsulation efficiency, yield and some quality characteristics (particle size, moisture content, water activity, bulk density) of microcapsules, produced by using six different optimum wall materials combinations, were determined. Oxidative stability of microcapsules, produced using by optimal combinations and also exposed to accelerated oxidation, were analyzed. Response surface methodology was employed to optimize the process conditions which were wall material concentration, flaxseed oil ratio and sonication time to obtain the combination, most stable to oxidation.Optimal wall material combinations, determined according to results of mixture design, were maltodextrine/sodium caseinate (4/1), N-Lok/sodium caseinate (4/1), HiCap 100/gum arabic (1/1), maltodextrine/whey protein concentrate (4/1), N-Lok/gum arabic (1:3) and HiCap 100/whey protein concentrate (4/1). Results revealed that, generally, microcapsules produced by ultrasonic homogenization had smaller emulsion and microcapsule particle size and higher microencapsulation efficiency compared to classical homogenization. Although the wall material combination was effective on emulsion particle size, it did not significantly affect microcapsule particle size.It was determined that the most stable microcapsules to oxidation were produced with maltodextrine/whey protein concentrate, however, microcapsules produced with gum arabic combinations rapidly oxidized. Oxidative stability was found to be more dependent to wall material compositions than surface oil content.According to the response surface methodology results, 90.2 % microencapsulation efficiency and 60.0% microencapsulation yield could be obtained using 20% wall material concentration, 35.1% flaxseed oil and 120 s of sonication time.