Enhanced stability and bioaccessibility of nobiletin in whey protein/cinnamaldehyde-stabilized microcapsules and application in yogurt

Polymethoxylated flavones (nobiletin, tangeretin, etc) have excellent bioactivity, but low water-solubility and high crystallization. We developed the cinnamaldehyde (CA)-modified whey protein (WPC)-stabilized microcapsules (WPC/CA microcapsules) to encapsulate nobiletin. Microcapsules showed spherical structure and mono-modal particle size distribution after dispersing in water regardless of CA concentration. The presence of CA increased the stability of nobiletin in emulsions and microcapsules, and inhibited the formation of nobiletin crystals. in vitro digestion results demonstrated that nobiletin in microcapsules had much higher bioaccessibility (82 %–94 %) than that in emulsions (68 %–83 %). The presence of CA maintained or increased the bioaccessiiblity of nobiletin both in emulsions as well as microcapsules. The formation of nobiletin crystals in stomach decreased in WPC/CA microcapsules. The results suggested that nobiletin-fortified yogurts could be produced by adding WPC/CA microcapsules, rather than WPC/CA emulsions. Also, microcapsules-incorporated yogurt would have better physical stability, if the amount of WPC/CA microcapsules and nobiletin was carefully designed. The optimized amount of CA-loaded microcapsules was 2 %–4 % in yogurt and the nobiletin content was 13−26 mg/100 g yogurt. This knowledge can be of great significance for the development of delivery systems of polymethoxylated flavones and their functional foods.