Calcium-chelating improved zein peptide stability, cellular uptake, and bioactivity by influencing the structural characterization

To improve the calcium intake, stability, and functional properties, calcium-chelating zein peptide (Ca-ZP) was developed from zein. The preparation conditions, structural characterization, stability, cellular uptake, antioxidant and antihypertensive activities of the Ca-ZP were investigated compared to the zein peptide (ZP). The highest calcium content and yield of Ca-ZP were 85.71 % and 42.91 %, respectively. After binding ZP carboxyl and amino groups with Ca2+, Ca-ZP was formed, confirmed by structural analyses. Moreover, Ca-ZP exhibited good stability at wide pHs, temperatures, and under-simulated gastrointestinal digestion in vitro, as well as antioxidant and ACE inhibitory capacity with the IC50 values of DPPH scavenging, hydroxyl radical scavenging, and ACE inhibitory activities of 0.48, 0.96, and 0.49 mg/mL respectively. Ca-ZP gastrointestinal digestive fluid showed higher calcium transport and absorption capacity than CaCl2 digestive fluid. Overall, Ca-ZP possessed high calcium-binding capacity, calcium absorption bioavailability, stability, and bioactivity. This work provides a promising approach for preparing calcium-chelating zein peptides, which are applicable as calcium supplements, antioxidants, and antihypertensive products.