Synergistic actions of proteolytic enzymes for production of soy protein hydrolysates with antioxidant activities: An approach based on enzymes specificities

The objective of this study was to investigate the enzymatic hydrolysis of soy protein isolate by screening individual and blended commercial protease preparations using a statistical mixture design. Information about the modulation of thermal inactivation of the enzyme by substrate or products of hydrolysis and the determination of synergistic effects between the enzymes on production of soy protein hydrolysates with antioxidant activities were reported. The kinetic parameters for thermal inactivation measured under reactive and non-reactive conditions indicated that product inhibition was not significant on soy protein hydrolysis using the commercial proteases Flavourzyme® 500 L, Alcalase® 2.4 L and YeastMax A. For DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging, the hydrolysates obtained with Flavourzyme® 500 L combined with Alcalase® 2.4 L showed the higher synergistic effect with increases of 10.9% and 13.2% in antioxidant activity as compared to the hydrolysates produced with individual enzymes. The hydrolysates obtained using the ternary mixtures of Flavourzyme® 500 L, Alcalase® 2.4 L and YeastMax A showed the highest power of inhibition of linoleic acid autoxidation. On the other hand, for reducing power assay and total antioxidant activity, the most of all interactions was antagonistic with high antioxidant activity detected for the hydrolysates produced using Flavourzyme® 500 L, individually.