The Digestion Characteristic of Protein Hydrolysate of Soft-shelled Turtle Egg and Its Effects on Antioxidative and α-Glucosidase Inhibitory Activities

Antioxidant intervention and inhibition of α-glucosidase activity are the effective strategies for prevention and treatment of diabetes. In this study, protein of soft-shelled turtle egg was hydrolyzed by papain, and hydrolysate fraction (HF) with low molecular weight < 2.5 ku was separated by ultrafiltration. The digestive characteristic of HF and changes of antioxidative and α-glucosidase inhibitory activities were investigated using in vitro simulated gastrointestinal digestion model. The results showed that the HF had a good color (yellowish green), and its aqueous solution was colorless and transparent. The chromatographic peaks of HF were slightly altered after gastric digestion, indicating that it had a good stability in stomach. However, the original chromatographic peaks were decreased after gastrointestinal digestion, and even some peaks were disappeared. Novel chromatographic peaks were correspondingly formed, and the peptide contents were also increased, indicating that some bioactive peptides in HF were digested to produce shorter peptides. The IC50 values (mg/mL) of DPPH radical-scavenging activities for HF before digestion and after gastric and gastrointestinal digestions were 13.61, 6.79 and 3.56, respectively. The IC50 values (mg/mL) of ABTS radical-scavenging activities were 18.21, 6.79 and 3.56, respectively. The IC50 values(mg/mL) of α-glucosidase inhibitory activities were 17.96, 10.81 and < 1, respectively. Therefore, HF with low molecular weight < 2.5 ku of soft-shelled turtle egg has a potential hypoglycemic effect, and its products still has a strong or even better hypoglycemic potential after gastrointestinal digestion. © 2022 Chinese Institute of Food Science and Technology. All rights reserved.