Sodium caseinate particles with co-encapsulated resveratrol and epigallocatechin-3-gallate for inhibiting the oxidation of fish oil emulsions

In oil-in-water emulsions, a single phenolic compound has been used as interfacial antioxidant. The co-encapsulated polyphenols may produce more supper stability or bioactivity than a single encapsulated one. This study used epigallocatechin-3-gallate (EGCG) and resveratrol as model polyphenols with different solubility. Their co-encapsulation in SC particles was analyzed on the basis of particle characterization, loading efficiency, antioxidant activity, polyphenolic microenvironment and retention. When the polyphenols' concentration was 0.4 mM, 98% EGCG and 68% resveratrol were co-encapsulated in sodium caseinate (SC) particles. The SC particles containing dual polyphenols were then used to stabilize fish oil emulsions, which were analyzed in term of particle characterization, oil oxidation, polyphenolic partition and retention. When the content of fish oil was 10%, there were 77% resveratrol in the emulsified oil droplets and 87% EGCG at the oil-water interface. The co-encapsulated EGCG improved the stability of resveratrol in SC particles and protected fish oil emulsions against oxidation prior to resveratrol. These results are instructive for the combination of multiple bioactive compounds for the applications in foods and pharmaceuticals.