Response surface methodology (RSM) was used to optimize the hydrolysis conditions (temperature, pH and Alcalase (R) 2,4L concentration), in order to obtain the hydrolysate with the strongest antioxidant activity using the 1,1-diphenyl-2-picryl-hydrazyl (DPPH.) decolouration assay. The optimum conditions obtained from experiments were pH 9.7, 66.2 degrees C, enzyme concentration = 68.1 Anson units (AU)/kg crude protein. The analysis of variance in RSM showed that pH and temperature (T) were the most important factors of the process (P < 0.001). The experimental conditions produced both an enzymatic and chemical protein solubilization. (C) 2007 Elsevier Ltd. All rights reserved.