Preparation and Investigation of Bioactive Properties of Protein Hydrolysates from Yogurt Whey

Yogurt whey contains lactose, lactic acid, soluble proteins, water-soluble vitamins, especially B vitamins, and minerals. Yogurt whey proteins can be a good source of bioactive peptides. In this study, we investigated the effect of enzyme type (pepsin and trypsin), temperature (37 and 50 °C) and time (120 and 240 min) of enzymatic hydrolysis on bioactive properties of protein hydrolysates prepared from yogurt whey. The results showed that increasing the enzymatic hydrolysis time from 120 to 240 min, increased the degree of hydrolysis, antioxidant activity (iron ion chelating activity, FRAP reducing activity and ABTS cation radical inhibitory activity) and antibacterial properties against various pathogenic bacteria (Escherichia coli, Staphylococcus aureus, Salmonella typhimurium and Listeria monocytogenes). Moreover, increasing the enzymatic hydrolysis temperature from 37 to 50 °C increased the degree of hydrolysis and decreased antioxidant activity and antibacterial property against Salmonella typhimurium. The antioxidant activity, antibacterial properties and hydrolysis degree of yogurt whey protein hydrolysates produced by trypsin were higher than those of pepsin. Two hydrolysates, were prepared with trypsin at 37 °C and pepsin at 50 °C for 240 min, were selected as the best samples in terms of bioactive properties.