Study On The Development And Utilization Of Soybean Residue

Soybean residue is an industrial waste produced during the production of soybean food.It has the characteristics of high water content,high cellulose,high protein,low fat and being rich in mineral elements.However,the nutrients contained in bean dregs,such as protein and cellulose,cannot be directly digested,absorbed and utilized by animals.Therefore,it is necessary to increase the nutritional value of the bean dregs by microbial fermentation.In this study,the research object was the bean dregs produced by the production of soybean milk powder by Guangdong Biquan Food Technology Co.,Ltd.Four different substrates,namely,heihe 43 pure bean dreg,heihe 43 bean dreg,wheat bran,huachun 6bean powder,and huachun 6 pure bean powder,were fermented using the single strain of bacillus natto screened by commercial natto powder(no.N-1).The relative yield of TAME activity unit,soluble total sugar and free total amino acid of nattokinase produced were taken as an indicator,evaluating the optimum water content,temperature,time,inoculum size,and the optimum ratio of added wheat bran and soy flour during fermentation.The 300 sets of data measured by different fermentation conditions,substrates and consideration indicators were analyzed,and the following conclusions were drawn:(1)Screening of Bacillus natto: 6 strains were screened through 6 different commercially available Bacillus natto bacteria: N-1,N-2,N-309,N-310,N-311,N-BS single strain of Bacillus natto.Bacillus natto N-1 was selected as the main strain for fermentation according to the characteristics of Bacillus natto N-1 including phenotypes,products,etc.N-1 grew slowly with more obvious dissolved circle,larger and concentrated colony,and milky white mucosa accumulating more on the surface.The enzyme accumulation of N-1 was large,which was suitable for the fermentation of bean dregs.Based on the results of measurement of the growth curve,we found that N-1 was cultured for 13.5 hours on the condition of 200 r/min and 30°C,the OD value was 0.9686.While the culture time lasted for 14.5 hours,the OD value reached 1.3073.Therefore,the best inoculation time of N-1 can be set at around 14 hours.(2)The optimum water content of pure soybean residue fermentation was about 60%,the optimum temperature was 30-35?,the optimal inoculum was 5-9%,and the optimalfermentation time was 30-40 hours.At this time,the TAME activity unit of nattokinase in0.1 m L of the crude enzyme solution can reach 0.18 ?/m L,the soluble total sugar in 0.5 m L of the crude enzyme solution was 728.60 ?g,and the free total amino acid in 0.1 m L of the crude enzyme solution was 15.67 ?mol.(3)When bean residue: when wheat bran was 5:2,the optimum water content for fermentation was about 60%,the optimal temperature was 30-35?,the optimal inoculum was 9%,and the optimal fermentation time was 30-40 hours.Taking industrial fermentation cost into main consideration,the optimal fermentation ratio was bean dregs: wheat bran =5:2,which can reduce the cost largely in some certain extent.At this time,the TAME activity unit of nattokinase in 0.1 m L of the crude enzyme solution can reach 0.36 ?/m L,the soluble total sugar in the 0.5 m L crude enzyme solution was 4790.61 ?g,and the free total amino acid in 0.1 m L of the crude enzyme solution was 66.63 ? mol.(4)When bean residue: when soy flour was 5:2,the optimum water content for fermentation was about 50%,the optimum fermentation temperature was 35?,the optimal inoculum was 9%,and the optimal fermentation time was 30-40 hours.The mixed substrate extracts the nattokinase,and the optimal fermentation ratio was 5:5.At this time,the cost of the fermentation base can be reduced,and the bottom material produced by the fermentation was rich in nutrients making large contributions to the subsequent utilization of the fermentation residue.At this time,the TAME activity unit of nattokinase in 0.1 m L of the crude enzyme solution was up to 0.53 ?/m L,the soluble total sugar in the 0.5 m L crude enzyme solution was 6009.47 ?g,and the free total amino acid in 0.1 m L of the crude enzyme solution was 127.65 ?mol.(5)The optimum water content of pure soybean powder fermentation was about 50%,the optimum temperature was 30 ?,the optimal inoculum was 5%,and the optimal fermentation time was 40 hours.At this time,the TAME activity unit of nattokinase in 0.1m L of the crude enzyme solution can reach 3.61 ?/m L,the soluble total sugar in the 0.5 m L crude enzyme solution was 13028.25 ?g,and the free total amino acid in the 0.1 m L crude enzyme solution was 427.97 ?mol.