Study On The Preparition Of Soybean Peptides With Defatted Soy Meal By Solid Fermention

Defatted soybean meal is a kind of protein sources of the full price, which protein content is as high as 40%-50%, containing eight essential amino acids which human need. Because of defatted soybean meal fermentation and enzyme hydrolysis, macromolecules are cut into sections of the small molecule, which is soybean peptide, and thereby enhance the utilization of soybean peptides. Soybean peptides, which can be a kind of potential function food, apply widely in many areas. Soybean protein also is a superior protein. It can be hydrolyzed into soybean peptides. Using of fungal growth at the secretion of enzymes in the degradation of defatted soybean protein and polysaccharide to become a low-molecular-weight sugars, amino acids and soybean peptides can improve the capability of improving digestion and absorption rate. Solid-state fermentation process is simple, low energy consumption and less investment advantages. Microorganisms can decorate and recombine some structures of bitter peptides, so the structures of peptides between the peptides and amino acids residues will be changed and resettled. It conquers some defects, such as large bitterness and bad taste. Aspergillus oryzaeA-9005 and Aspergillus niger3.350 can hydrolysis the protein of soybean meal, which is cheap and easy to find as raw material to produce soybean peptide. The method will cut down production cost, and accelerate the industrialization of functional peptides.This thesis focused on the following three aspects: First, measure the protease activity and conversion rate of soybean peptide in dynamic fermentation progress of defatted soybean meal. The soybean peptides were prepared by solid state fermenting defatted soybean with the mixture of Aspergillusoryzae A-9005 and Aspergillus Niger 3.350. Second, make sure the single complication condition through the analyze of the dynamic fermentation results and do single complication test. Third, optimize the conditions of fermentation by doing orthogonal test.The physical and chemical indicators of the dynamic changes are as follows:①Aspergillus niger protease: 0-84h-living increased gradually, after 96h live-started declined, and the maximum can reach in about 460U/g. Aspergillus oryzae protease: 0-24h slower activity increased activity basicly stay zero, 24-84hactivity rosed faster. When the fermentation got to 132h, the basic activity reached the maximum, after 180h the live-a slight decreased, Max can reach about 1100U/g. ②Peptide conversion rate: 0-96h peptide conversion rate gradually increased and reached the maximum, after 96h changes of the conversion rate tended to not change the basic flat.The same fermentation conditions, and Aspergillus fermentation of soybean meal peptide conversion rate was greater than Aspergillus oryzae.③Reducing sugar: 0-36h reducing sugar rapidly increased the total, 36h later gradually declined. Total sugar: the whole process of fermentation of sugar declined. A dynamic research based on single-factor test, and then by orthogonal testing and conversion and a peptide-living index for the fermentation process to determine the optimal conditions:①Aspergillus Niger: raw materials is (soybean / wheat bran) 90%, pH5.8, temperature of 30℃, fermentation time 96h.②Aspergillus oryzae: raw materials is (soybean / wheat bran) 93%, pH 6.8, temperature of 33℃, fermentation time 102h.③The results suggest that: Under the conditions of fermentation for 144h, the best fermentation conditions of producing soybean peptides by solid state fermenting defatted soybean with the mixture AspergillusoryzaeA-9005 and Aspergillus niger3.350 are: pH6.0, the ratio of inoculation 2∶1; the temperature of fermentation was 32℃.