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

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, confirmedby 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 digestivefluid. 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.