Release of anthocyanins encapsulated by high hydrostatic pressure-treated micellar casein: Effect of serum Ca²⁺ level during in vitro digestion

Anthocyanins (ACNs) possess the natural advantage of gastric stabilization and has the potential to be adopted for the delivery system design for prolonged gastric release to enhance its bioavailability. In this study, micellar casein treated with high hydrostatic pressure (100, 300, and 500 MPa) was applied to load ACNs, and exogenous serum Ca²⁺ (0.15, 2, and 5 mM) controlled the gastric aggregation behavior of casein during in vitro digestion. The results showed that the high level of pressure dissociated the micellar structure and provided more cross-linking possibilities for serum Ca²⁺. Furthermore, the high serum Ca²⁺ level enhanced gastric aggregation of casein subunits and submicelles leading to delayed gastric emptying, and controlled the slow release of ACNs, which contributed to prolong the ACN retention in the stomach. Industrial relevance: The application of high hydrostatic pressure (HHP) in food sterilization has been relatively mature, and there is an urgent need to expand it toward the nutritional and health field in search of high added value. Herein, HHP was applied to solve the problem of low bioavailability of ACNs based on the ingenious relationship between HHP and casein micelles. The research data can help to develop nutraceuticals or high satiety foods with ACNs as the main functional component at low cost.