Preparation of Hypoglycemic Functional Peptides from Corn Germ Meal and Its Hypoglycemic Activity in Vitro

In order to investigate the optimal preparation process and in vitro hypoglycemic activity of functional peptides from corn germ meal (CGMPs), this study used corn germ meal as the raw material, and the inhibition rates of dipeptidyl peptidase-Ⅳ (DPP-Ⅳ) and α-glucosidase as indicators. CGMPs were prepared by enzymatic hydrolysis with alcalase. The preparation of CGMPs was optimized using single-factor experiments and response surface methodology. On this basis, the enzymatic reaction kinetics of CGMPs and their inhibitory effects on DPP-Ⅳ activity in Caco-2 cells were analyzed. The optimal enzymatic hydrolysis conditions were as follows: Substrate concentration of corn germ meal 4%, enzyme dosage of alcalase 1003 U/g, enzymatic hydrolysis pH7.5, enzymatic hydrolysis temperature 59.5 ℃, and reaction time 3 h. Under these conditions, the inhibition rates of CGMPs on α-glucosidase and DPP-Ⅳ were 75.74%±2.02% and 61.64%±2.07% (1 mg/mL), respectively. The enzymatic reaction kinetics results showed that the inhibition of CGMPs on DPP-Ⅳ was competitive and reversible. In addition, CGMPs also exhibited good DPP-Ⅳ inhibitory ability at the in vitro cellular level, indicating that they could be used as a functional food ingredient for the development of hypoglycemic functional foods. This study provides a theoretical basis for the high-value utilization of corn germ meal protein resources.