Anti-Diabetic Properties of Hydrolysates from Egg White Proteins Using Immobilized Enzymes Followed by in vitro Gastrointestinal Digestion

Background and Objective: Enzyme-assisted hydrolysis of the proteins from food sources is an effective way to generate peptides with various bioactive properties. Furthermore, enzyme immobilization is a way to recycle enzymes for the future uses. The objective of this study was to investigate the effects of neutrase and thermolysin immobilization on the enzyme properties and in vitro anti-diabetic properties of intestinal digests achieved by the simulated digestion of egg white protein hydrolysates. Material and Methods: Neutrase and thermolysin were immobilized on cellulose-coated magnetite nanoparticles. Then, enzyme activity, thermal resistance, reusability and optimum conditions of the egg white protein hydrolysis were assessed. Egg white protein hydrolysates were then digested in vitro and inhibitory activities of the intestinal digests against dipeptidyl peptidase IV (DPP-IV) and α-glucosidase were investigated. Results and Conclusion: Enzymes immobilization resulted in increases in the thermal stabilities of them. Optimum temperatures for the egg white protein hydrolysis increased by 4.0 and 3.2 °C for neutrase and thermolysin, respectively. Digests from the hydrolysates of free neutrase effectively inhibited DPP-IV and α-glucosidase by 17.9 and 29.7%, respectively. These values for the hydrolysates released by the free thermolysin were higher (37.2 and 35.1%, respectively). The enzyme immobilization resulted in a 4.4% decrease in DPP-IV inhibitory activities of the digests for the hydrolysates from neutrase and a 28.6% decrease for those from thermolysin. Decreases in α-glucosidase inhibition due to the immobilization included 9.8% for neutrase and 12.2% for thermolysin for the digests from the hydrolysates. Based on the results from the current study, hydrolysates from the egg white proteins achieved by the free and immobilized neutrase and thermolysin can be used in formulations of the functional foods and nutraceuticals with multifunctional properties.