Glyceride product from lipase-catalyzed hydrolysis of fish oil (large-scale) is a rich source of n-3 PUFA (49.62%); but it is prone to oxidation. Our aim was to encapsulate this product by a mixture of whey powder and sodium caseinate (4:1) as a new wall material. The emulsification was done using ultrasonication in different powers (180-380 W) and times (1-3 min) and, then, the emulsions were freeze-dried to obtain the powders. Based on encapsulation efficiency, sonication (88-94%) could inhibit the presence of oil at the surface of powder particles in comparison with the samples prepared without sonication (control, 68%). The highest oxidation rate and the lowest L-value were found for the unencapsulated glyceride product stored in air atmosphere followed by the control powder, the powders from sonication treatment and the unencapsulated glyceride product under N2, respectively. In the case of oxidative stability of the samples, the sonication time was more significant than sonication power. According to our results, a sonication treatment of 380 W for 3 min was recommended to prepare parent emulsions during fish oil encapsulation.
Keywords: Fish oil encapsulation; Image processing; Oxidative stability; Scanning electron microscopy; Ultrasound-assisted emulsification.