eng Oriental Scientific Publishing Company Biosciences Biotechnology Research Asia 0973-1245 2017-03-25 14 1 193 200 10.13005/bbra/2435 21634 article Leila Rostammiry 1 Mohammad reza Saeidiasl 1 Reza Safari 2 Rohollah Javadian 3 Department of Food Science and Technology, Sabzevar Branch, Islamic Azad University, Sabzevar, Iran. Agricultural Research Education and Extension Organization (AREEO),Iranian Fisheries Science Research Institute (IFSRI), Caspian Sea Ecology Research Center, Sari, Iran. Department of Fisheries, Ghaemshar Branch, Islamic Azad University, Ghaemshar, Iran. Soybean protein isolate was hydrolyzed to obtain soybean polypeptide solution using alcalase and trypsin. The effects of three independent variables including E/S (X₁), temperature (X₂) and pH (X₃), at three levels in actual and coded values (-1, 0, +1), were evaluated to determine the best complex of variables and  the degree of hydrolysis (DH) has been considered as response to variables. Response Surface Methodology (RSM) based on Box-Behnken Design was applied to optimization the condition of enzymatic hydrolysis of soy protein isolate. The optimal reaction conditions of soybean protein isolate hydrolyzed by alcalase and trypsin were that the E/S was 4.38 and 4.49%; pH was 8 and 7.11; temperature was 46.21 and 41.85°C, respectively and hydrolysis time wa s 45 and 60 minute respectively. RSM generated model predicted DH that 15.9782% for alcalase and 20.471% for trypsin could be achieved at these conditions and this model was valid based on the DH value obtained from the experimental study which was quite similar with the predicted value. High yield of DH obtained from the optimization process could produce soy protein hydrolysate with good nutritional and functional properties. https://www.biotech-asia.org/vol14no1/optimization-of-the-enzymatic-hydrolysis-of-soy-protein-isolate-by-alcalase-and-trypsin/ acalase;  Response Surface Methodolgy Soy Protein Isolate; trypsin;