Evaluating the effect of conjugation on the bioactivities of whey protein hydrolysates

In this study, the ability of a whey protein hydrolysate to exhibit the antimicrobial, antioxidant, and antihypertensive behavior after combining with a reducing carbohydrate was studied. Whey protein hydrolysates with varying degrees of hydrolysis (WPH10, WPH15, and WPH20) were determined for their antimicrobial, antioxidant, and antihypertensive activities. Of these, hydrolysate (WPH10) exhibited the highest antimicrobial activity (with 10-11.2 mm zone of inhibition) against tested microorganisms: Listeria innocua, Staphylococcus aureus, and Bacillus coagulans. Also, the WPH10 exhibited the highest antioxidant (866.56 TEAC µmol/L) and antihypertensive (67.52%) attributes. Hence, based on the highest bioactivity, hydrolysate WPH10 was selected for conjugation with maltodextrin, and the effect of conjugation on the bioactivities was evaluated. The conjugated WPH10 solution demonstrated higher antimicrobial (17.16 mm) and antioxidant activity (1044.37 TEAC µmol/L), whereas a slight decrease in the antihypertensive activity (65.4%) was observed, as compared to WPH10 alone. The conjugated solution was further spray dried and alternatively, freeze-dried. The dried WPH10 conjugate exhibited even higher antimicrobial (18.5 mm) and antioxidant activity (1268.89 TEAC µmol/L) while retaining the antihypertensive activity (65.6%). Overall, the results indicate the ability of the WPH10-maltodextrin to retain the bioactive behavior after combining with a reduced carbohydrate. PRACTICAL APPLICATION: Whey protein hydrolysates upon conjugation with carbohydrates retain the bioactive properties of whey protein, which provides opportunities for application as an ingredient to develop novel health formulations.