Optimization of Extraction of Peanut Proteins with Water by Response Surface Methodology

Water extraction of peanut proteins was optimized to maximize protein extraction, Y 1 and protein concentration in the extract, Y 2 . A central composite design involving solids‐to‐water ratio (X 1 ), pH (X 2 ), temperature (X 3 ) and time (X 4 ) was used, and second‐order models for Y 1 and Y 2 were employed to generate response surfaces. The optimum conditions to obtain Y 1 ≥ 85% and Y 2 ≥ 2.5% were X 1 = 1:8; X 2 = 8.0; X 3 = 50 °C; X 4 = 30 min. Estimates of Y 1 and Y 2 at the optimum were 85.29% and 2.7%, respectively. Experimental verification gave values of Y 1 = 84.39%± 0.78 and Y 2 = 2.80%± 0.02. Y 1 and Y 2 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.