Antioxidant properties of hydrolysates of wheat gluten as influenced by process conditions

Abstract

The effects of some relevant process parameters for the Alcalase-catalyzed wheat gluten hydrolysis such as gluten concentration (X1; 1-9% w/v), temperature (X2; 40-60 oC), pH (X3; 7-9) and enzyme/substrate ratio, [E]/[S] ratio (X4; 0.25– 0.75 AU/g of protein) were investigated by the means of an experimental design. The second-order models developed for the degree of hydrolysis, DH, DPPH and ABTS radical scavenging activity of gluten hydrolysates were significant (p<0.01) with a high value of coefficients of determination (0.981-0.992). The statistical analysis showed that each variable had a significant effect on degree of hydrolysis and the antioxidant capacity of both tested systems. Hydrolysis up to around DH = 15% improved DPPH radical scavenging activity, while excessive hydrolysis worsened it. It seemed there was not a correspondence between degree of hydrolysis and ABTS activity at different protein concentrations, suggesting that there were peptides with considerable size presenting a good antioxidant capacity.