Antioxidant activity of cowpea protein isolate hydrolyzed by pepsin

Abstract

Antioxidant activity was studied for hydrolysates obtained from cowpea protein isolate by enzymatic hydrolysis using pepsin. Effects of 3 hydrolysis parameters: pH, temperature, and time were analysed using response surface methodology. A second-order polynomial model was used for predicting antioxidant activity of the hydrolysates. This model was adequate to fit experimental data and explained more than 85% of the variation. Interaction between pH and temperature was the major effect affecting antioxidant activity. Optimum antioxidant activity was observed after hydrolysis for 176 min, at pH 2.15, and temperature 38.2 °C. Under these conditions, the predicted antioxidant activity (22.69%) was in agreement with the experimental one. Degree of hydrolysis of the hydrolysate under optimum conditions was 25.70%, and the electrophoretic profile revealed the cleavage of several protein bands present in the isolate.