Abstract: In this study, fish oil-curcumin microcapsules were prepared by using heat-denatured whey protein isolate (hWPI), whey protein isolate (WPI), and maltodextrin (MD) as wall materials, and its physicochemical properties were analyzed. The results showed that the particle size distribution of the prepared nano-emulsion, consisting of 5% hWPI, 5% WPI, and 5% MD, was unimodal. The surface of the microcapsules showed no cracks, and the encapsulation efficiency reached up to 96.5%. Curcumin addition did not significantly affect the particle size, ζ-potential, or encapsulation efficiency, yet it markedly improved the microcapsules’ re-dissolution rate (from 74.65% to 82.01%) and slightly enhanced the thermal stability. These results could be explained by the fact that curcumin and protein formed a soluble complex through hydrophobic interaction and hydrogen bonds. As the content of curcumin increased, more curcumin was adsorbed to the oil-water interface, which delayed the degradation of polyunsaturated fatty acids and improved the oxidative stability of microcapsules. After storage at 45 ℃ for 35 days, the retention rates of curcumin, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) in the 0.2% curcumin-loaded microcapsules were 81%, 39% and 39%, respectively. This study provides a reference for the development of industrial microcapsule products of functional oils and polyphenols.

Key words: fish oil; curcumin; microcapsules; whey protein; high encapsulation efficiency; stabilization