Preparing Peptides With Soybean Protein By Microorganism Degradation

The soybean peptide is produced by enzyme hydrolyzing or microorganism fermentating soybean protein into peptide with the molecular weight below 10,000 Da. Comparing with the soybean protein, it has the good physics and chemistry characteristic and has become an important aspect of soybean intensive processing.In this article, the microorganism—Bacillus.natto, Bacillus.subtilus, Actino mucor elegans and Monascus which are commonly used in the traditional fermentation food were used to ferment the soybean to obtain the soybean peptide directly. This thesis we have researched the changing of protein components in microorganism fermentative process; the effect of the different fermentation condition on microorganism fermentation soybean; the molecular weight distribution of decomposition product and the influence of the supplementary material on fermentation to prepare easily digest leisure food by carrying on the short-term , the results are as followed:(1) By analyzing the change of proteinase activities in microorganism fermentate process, we concluded that the microorganism had the high proteinase activity ,from 2.92-10.4U/g,and good decomposition to the soybean protein. (2) Longding method was used to differentiate the soybean protein after being fermentated, the result indicated that the macro-molecule protein was degraded for the different molecular weight protein, comparing with the soybean protein, the lowest molecular weight protein's increase was most remarkable, being the 15-20 times for not after the decomposition soybean in low molecular protein. The macro-molecule protein is degraded for the molecular weight different high school low member protein, compares with the soybean protein, You Yidi the member protein increase is most remarkable, is not after the decomposition soybean in low molecular protein 15-20 time(3)We studied the effect of the pH, the temperature and the oxygen transmission on the fermentation , with the low molecular nitrogen content and angiotensin I-converting enzyme inhibitory activities as primarily considering the factor. The results indicated: using the water of pH4- 6 to soak the soybean ,the fermentation temperature of 30-35 C and turning material every 8-24 h are suitable for protein decomposition.(4) The soybean's protein molecular weight by microorganism is below 10000Da after the the SDS-PAGE and the molecular weight, which the protein of fermented soybean after the precipitation by tannin were analyzed by mass spectrum ,is small distributing about 1000-1500Da;(5) The effect of different supplementary material on fermentation soybean were studied. The results indicated: with the lactic acid or the citric acid adjustment soybean' soaking water with is pH5or 6, adding 3%-5% rice powder are suitable for microorganism. After the fermentation by four microorganism, we have obtained the soybean with good color and fragrance and higher ammoniacal nictrogen content.