Research On The Effect Of Different Microbial Liquid Fermentation On Nutritional Value Of Soybean Protein

According to function of microbial fermentation that reduce the content of soybean anti-nutritional factors; improve the utilization efficiency of soybean protein digestion; and also change the amino acid composition of soybean protein, microbial fermentation can affect soy protein nutritional quality. Ten microorganisms(Bacillus subtilis, Bacillus lichenifor mis Bacillus natto, Saccharomyces cerevisiae, plants Lactobacillus, Aspergillus niger, Aspergillus oryzae, animal bifidobacteria, Bifidobacterium longum,Bifidobacterium breve) were used in this experiment to liquid fermentation defatted soybean flour, the fermentation time last48h, samples were detected at Oh,12h,24h,48h respectively. The lose of dry matter, free amino acid, acid soluble protein, soybean peptide, essential amino acid index were measured at each time and each strain fermentation samples. Comprehensive evaluation of the fermentation products was given to screen the appropriate liquid fermentation soybean strains. This research supplied a solid theoretical basis for the further study on the fermentation of soybean protein feed.The results were followed:1. After48h fermentation, all the10species of microorganisms could reduce dry matter content, but they had a different effect on the dry matter content. Compared to the other microorganisms, Bacillus natto was demonstrated had a lowest effect on reducing the dry matter content. Animal bifidobacteria, Bifidobacterium longum, Bifidobacterium breve were stronger than Bacillus natto but lower than the other microorganisms on reducing the dry matter content.(P>0.05)2. After48h fermentation, all the10species of microorganisms can reduce essential amino acid index (P>0.05), As for the pig growth of certain essential amino acid content have some differences, Bacillus licheniformis, Lactobacillus and Saccharomyces cerevisiae smallest changes in essential amino acids, of which only Phe Saccharomyces cerevisiae has decreased substantially; while Aspergillus niger and Aspergillus oryzae mold most significant decline in essential amino acids, particularly Arg, His, Phe sharpest decrease, and the remaining types of essential amino acids has decreased substantially; while Bacillus subtilis, Bacillus natto fermentation broth, and three Bifidobacterium there are different levels of essential amino acids decline, but declines are small, especially the pig growth limiting amino acids Lys, Met, Trp, etc. did not change significantly, although to some extent reduce the remaining amino acids, but decreased to a lesser extent.3. After48h fermentation, there are more free amino acids and soy peptides in the defatted whole soya bean flour. Free amino acids and soy peptides had a significantly positive correlation with fermentation time in the defatted whole soya bean flour (P<0.01). After48h fermentation, free amino acids and soy peptides in the defatted whole soya bean flour that were fermented by Aspergillus niger, Bacillus natto animal bifidobacteria, Bifidobacterium longum and Bifidobacterium breve, were significantly higher than the other microorganisms.Conclusions:1. After48h fermentation, all the10species of microorganisms can improve the nutritional quality of soy protein,but molecular weight of the soy protein reduced content of free amino acids and peptides increased significantly improve animal digestive efficiency.2.48h fermentation period, the most suitable liquid fermentation strains of defatted soy flour was Bacillus natto, next were Bifidobacterium breve, animals Bifidobacterium and Bifidobacterium longum.