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.