Optimization of Soy Protein Salt Extracting Process Based on Fractional Factorial Design and Central Composite Design

A 27-3 IV fractional factorial design(FFD) is employed to determine soybean protein salt extraction conditions affecting the protein extraction efficiency,such as the ratio of sodium sulfite to sodium hexametaphosphate,salt concentration,the ratio of liquor to material,stirring rate,extraction time, extraction temperature,extraction times. Extraction temperature,the ratio of sodium sulfite to sodium hexametaphosphate and stirring rate are identified as key affecting factors, and their optimal levels are further investigated by a central composite design(CCD). The results show that the average extraction yield of soybean protein from 3 parallel experiments carried out using the extraction temperature 58 ℃,stirring rate 59 r/min,the ratio of sodium sulfite to sodium hexametaphosphate 3.83,salt concentration 35 g/L,the ratio of liquor to material 10∶1,extraction time 60 min and extraction 2 times is 61.76%±0.35%,which is in substantial agreement with the predicted value(62.10%).