Production of soy protein hydrolysates with high antioxidant activity

Today, there is a growing interest in natural antioxidants, among which special attention is paid to protein hydrolysates with increased antioxidant activity. In this study, the enzymatic proteolysis of soy protein isolate was studied in order to obtain hydrolysates with high antioxidant activity. Proteolytic enzyme preparations of microbial (Alcalase, Neutrase, Flavourzyme, Protozyme) and plant (papain, bromelain) origin were used for proteolysis. The total antioxidant capacity (OAE) was determined in the obtained hydrolysates, which was evaluated by three methods: FRAP, DPPH and ORAC (the results were expressed in mmol-eq. quercetin /l). Hydrolysis was performed with a 1:15 hydromodule, enzyme dosages of 0.5–2.0% by weight of the substrate, with pH and temperature maintained for 4 hours. It was found that microbial proteases provided a higher degree of hydrolysis (DH) compared to plant proteases: the maximum reached 14.95% for Alcalase, 13.89% for Flavourzyme, 11.00 for Neutral and 9.23 for Protozymes at a dosage of 2%, while for papain and bromelain – 5.06% and 5.30%, respectively. The SDS-PAGE analysis confirmed deeper protein cleavage under the action of microbial enzymes. According to the ORAC analysis, the hydrolysate obtained using Alcalase – 9487.27 mmol-eq demonstrated the highest antioxidant capacity. quercetin / l, and according to the FRAP method, hydrolysates of Alcalase, Neutrase and Protozyme (over 110 mmol-eq./l). The highest OAE by the DPPH method was observed in the Neutrase hydrolysate (37.49 mmol-eq/l). It has been shown that the hydrolysis process significantly increases the antioxidant properties compared to the native isolate. It has been established that the enzymes Alcalase, Neutrase, Flavourzyme and the domestic drug Protozyme are promising for the production of soy protein hydrolysates with pronounced antioxidant activity. The data obtained can be used in the development of functional ingredients for the food industry.