Preparation of peanut α-glucosidase inhibitory peptides via double-enzyme hydrolysis and evaluation of their in vitro gastrointestinal digestion stability

To efficiently utilize peanut protein resources and explore the hypoglycemic potential of its enzymatic hydrolysates, peanut protein was extracted by alkali dissolution and acid precipitation. Using the α-glucosidase inhibitory rate as the evaluation index, dual-enzyme hydrolysis conditions were optimized via response surface methodology. The results indicated that enzymatic hydrolysates derived from Yuhua 37 (a high-oleic peanut cultivar) possessed superior α-glucosidase inhibitory activity. Sequential hydrolysis of peanut protein was performed using alcalase followed by trypsin, and the optimal conditions were determined as follows: peanut protein mass concentration of 17 mg/mL, total enzyme dosage of 4.7% (mass ratio of the two enzymes was 1∶1), and total hydrolysis time of 156 min (enzyme action time ratio was 5∶1). Under these conditions, the α-glucosidase inhibitory rate of prepared peanut peptides reached 68.41%±0.45% at a peptide concentration of 2 mg/mL, with a corresponding degree of hydrolysis of 25.14%±0.04%. Compared with single-enzyme hydrolysis in preliminary experiments, the dual-enzyme strategy significantly reduced enzyme consumption while maintaining equivalent inhibitory activity. In vitro simulated gastrointestinal digestion exerted variable effects on the α-glucosidase inhibitory activity of peptides from different protein sources; specifically, the inhibitory activity of the self-prepared peanut peptides decreased signifficantly after digestion. In conclusion, the optimized dual-enzymatic hydrolysis process enables efficient preparation of highly active α-glucosidase inhibitory peanuts peptides with lower enzyme usage. However, their inhibitory activity is markedly attenuated after in vitro simulated gastrointestinal digestion.