Abstract:In order to explore the effect of exogenous protease pre-enzymolysis treatment on the gastrointestinal digestibility and antioxidant activity of eartnworm protein after gastrointestinal digestion. In this paper, five proteases were used to prepare different hydrolyzates of earthworm protease, and then the changes in the degree of hydrolysis, molecular weight distribution and in vitro antioxidant activities of these enzymatic hydrolyzates were investigated by simulated digestion in vitro. Among the five protease hydrolyzates, the hydrolysis degree of alkaline protease hydrolyzate was the highest, which was 40.8%. The scavenging rates of DPPH and ABTS free radicals were 38.46% and 79.83%, respectively, and the ORAC value was 0.70 μmol TE/mg. The degree of hydrolysis, DPPH free radical scavenging rate, and ORAC value of the alkaline protease hydrolyzate after gastrointestinal digestion were increased by 163.9%, 79.9% and 120%, respectively, compared with those obtained from direct gastrointestinal digestion (EWP) of earthworm protein. 10,823 peptides with molecular weight <3 ku were identified in GHEWP, and 11 peptides with the highest activity scores were screened by bioware.ucd.ie for activity threshold score and synthesized to verify the activity. Among them, ATSGFFVY, HCFVLY, HLASGWY, HRYSDF and HYANMY had better comprehensive antioxidant capacity. The quantum chemical calculation results showed that the active sites of ATSGFFVY, HCFVLY, HRYSDF and HYANMY might be located on Tyr-8, Tyr-6, Tyr-3, Tyr-2, respectively; the active site of HLASGWY may be located on Trp-6. This study showed that pre-enzymatic hydrolysis with alkaline protease could improve the digestibility of earthworm protein and enhance the antioxidant activity of its gastrointestinal digestion products.
