Preparation Of Small Peptide By Hydrolyzing Fermented Liquid Of Soybean Meal

The soybean polypeptides are a compound with molecular under 10000 Da which are obtained from hydrolysis of soybean protein.Compared with soybean protein, soybean polypeptides have more superior physical and chemical properties , also bioactivities. There are good prospective of exploitation and application in food industry and medical works.We studyed the effect of temperature, material-water ratio and time on hydrolysis of fermented soybean meal according to DH and TCA-SNI , and obtain the best hydrolysis conditions.Then we explores the preparation methods of small soybean meal peptides which combine the hydrolysis and microbial fermentation. We select the best protease, and get the optimum conditions for hydrolysis of soybean meal broth by protease.Finally we analyse the hydrolysate and come to the conclusion: The study shows the best hydrolysis conditions is temperature : 50℃, material-water ratio : 1: 6 (w/w), reaction time : 6 h. Trypsin is more efficient than Papain, Protamex, Neutrase and Alcalase2.4L. Trypsin can make a increase of DH after hydrolyzing fermented liquid of soybean meal.According to the result of single-factor and orthogonalexperiments, the optimum conditions for hydrolyzing fermented liquid of soybean meal by Trypsin is temperature: 60℃, pH 8.5, substrate concentration: 13% (w/w), ratio of enzyme to substrate: 600 u/g (soybean dregs). The reaction time is 1 h according to the molecular weight distribution of hydrolysate analyzed by means of GFC. Under this condition the DH of the hydrolysates reach 32.3% which has an increase of 6.1% than the DH of the hydrolysates before the hydrolysis, the TCA-SNI of the hydrolysates reach 67.2% which has an increase of 9.9% than the TCA-SNI of the hydrolysates before the hydrolysis.And 77.8% of them have the molecular weight range from 538 Da to 2659 Da.