Preparation, characterization and calcium release evaluation in vitro of casein phosphopeptides-soluble dietary fibers copolymers as calcium delivery system

Delivery systems based on food-grade biopolymers are of particular interest for food applications. Here, we introduce a new calcium delivery system with a high calcium-binding capacity and controlled calcium release. The system integrates casein phosphopeptides (CPP) with soluble dietary fibers (SDF). The physicochemical properties, calcium-binding capacities, controlled calcium release properties and formation mechanisms of the prepared copolymers with different mass ratios of CPP/SDF after thermal treatment were studied. The results showed that CPP-SDF copolymers significantly improved the calcium binding capacity (P < .05) from 11.63% to 46.8% and increased the calcium phosphate deposition time. The SDF in copolymers protected CPP from gastric enzyme hydrolysis so that most of the calcium was released under intestinal conditions in a controlled manner. Structural characterizations demonstrated different copolymer conformational states, and more calcium-binding sites existed within the CPP-SDF copolymers. The results show that copolymers based on food-sourced polymers are potential candidates for oral calcium delivery.