Optimization of extraction of peanut proteins with water by response surface methodology

Water extraction of peanut proteins was optimized to maximize protein extraction, Y1 and protein concentration in the extract, Y2. A central composite design involving solids-to-water ratio (X1), pH (X2), temperature (X3) and time (X4) was used, and second-order models for Y1 and Y2 were employed to generate response surfaces. The optimum conditions to obtain Y1 greater than or equal to 85% and Y2 greater than or equal to 2.5% were X1 = 1:8; X2 = 8.0; X3 = 50 degrees C; X4 = 30 min. Estimates of Y1 and Y2 at the optimum were 85.29% and 2.7%, respectively. Experimental verification gave values of Y1 = 84.39% +/- 0.78 and Y2 = 2.80% +/- 0.02. Y1 and Y2 were further maximized, as measured by absorbance of solution following centrifugation of the extract, when papain (0.05% g/g peanuts) was added and extraction was carried out at the optimum conditions