Abstract: Objective: The conditions for the extraction of trypsin inhibitor from low-temperature defatted soybean meal were optimized. Methods: pH, thermal denaturation temperature and ammonium sulfate saturation were identified to be main variables that influence extraction efficiency by the one-factor-at-a-time method. Based on the principles of Box-Behnken central composite design, response surface analysis was employed to explore the effects of pairwise interactions among the three variables at three levels on extraction efficiency. The optimum conditions for extracting soybean trypsin inhibitor from low-temperature defatted soybean meal were found as follows: extraction solvent pH of 5.1, thermal denaturation at 72.8 ℃ and ammonium sulfate saturation of 54.5% for the precipitation of trypsin inhibitor. Under these conditions, the extraction efficiency of trypsin inhibitor was up to 86%. Consequently, response surface methodology is feasible for the optimization of the extraction process for trypsin inhibitor from defatted soybean meal, and the optimized process is reliable.

Key words: soybean trypsin inhibitor, extraction, Box-Behnken experimental design