Novel strategy to the characterization and enhance the glycemic control properties of walnut-derived peptides via zinc chelation

•Effect of the peptides chelated zinc on hypoglycemic properties was first study.•The anti-diabetic activity was enhanced than before chelation.•Meanwhile, the antioxidant ability was also increased than before chelation.•WPH-Zn on antioxidant was better than LP5-Zn compared with before chelation.•WPH more potentially easier participating in coordination with Zn2 + than LP5. This study aimed to utilize zinc coordination to promote the hypoglycemic and antioxidant properties of walnut-derived peptides, such as walnut protein hydrolysate (WPH) and Leu-Pro-Leu-Leu-Arg (LPLLR, LP5), of which LP5 was previously identified from WPH. The optimal conditions for the chelation were a peptide-to-zinc ratio of 6:1, pH of 9, duration of 50 min, and temperature of 50 °C. The WPH-Zn and LP5-Zn complexes increased the α-glucosidase inhibition, α-amylase inhibition, and antioxidant activity more than WPH and LP5 (p