Evaluation of antioxidant, α-amylase-inhibitory and antimicrobial activities of wheat gluten hydrolysates produced by ficin protease

The object of this study was to produce bioactive hydrolysates from wheat gluten using ficin, a commercially important endopeptidase with plant origin, and evaluate antioxidant, antimicrobial and a-amylase inhibitory activities. Hydrolysate samples were collected at different time intervals (60, 120 and 180 min). Both samples obtained at 120 and 180 min were highly active against ABTS(+) radical. The sample collected at 180 min was the most active hydrolysate in terms of DPPH radical scavenging activity, ferrous ion-chelating and a-amylase inhibition, and was further fractionated by ultrafiltration into three peptide fractions, T3-F1 (MW > 10 kDa), T3-F2 (3 < MW < 10 kDa) and T3-F3 (MW < 3 kDa). These fractions were compared in terms of antioxidant and a-amylase inhibitory abilities. The T3-F3 fraction, exhibited the strongest DPPH scavenging activity. The highest values of ABTS(+) scavenging activity and a-amylase inhibition were detected in T3-F2 and T3-F3 and the lowest values in T3-F1, which were even lower than those of the parent hydrolysate. The fraction T3-F2 had the highest chelating ability and T3-F3 the lowest, even in comparison with the parent hydrolysate. The antibacterial properties of the hydrolysate sample collected at 180 min was evaluated against Staphylococcus aureus and Escherichia coli bacteria. The most significantly affected bacteria was S. aureus with the minimum inhibitory concentration value of 48 mg/mL, whereas the value obtained against E. coli was 52 mg/mL. The minimum bactericidal concentration was 60 mg/mL for both S. aureus and E. coli.