The Effect Of Neurospora Crassa Fermentation On Soybean Meal Protein And Its Properties

In this study,the method of making fermented feed with soybean meal was studied.Soybean meal,the main byproduct after soybean extracted oil was used as raw material.Neurospora crassa,isolated from traditional fermented food in Jiangxi province,produced cellulose enzyme and?-carotene,was used as fermentation strains.The possibility of degradation of macromolecular protein in soybean meal by Neurospora crassa and produce hypoallergenic and high digestibility of fermentation feed was studied.The experiment on the analysis of the nutrition and antinutritional factors in Neurospora crassa fermentation process of soybean meal was studied.In order to obtain a high protein hydrolysis,the culture condition of Neurospora crassa alone and Neurospora crassa and saccharomyces cerevisiae together was studied and optimized.The content of free amino acids and peptides of fermented soybean meal and in vitro digestibility were measured to evaluate the effect of fermentation.The functionality of the peptide in fermented soybean meal has been determined.The main results were as follows:(1)The objective of this study was to evaluate the change rules of nutritional components and anti-nutritional factors in Neurospora crassa fermentation process of soybean meal.The results indicated the degradation rate of crude fiber and the crude protein content were increased along with fermentation time growing.The crude fats were decreased.The total soluble sugar were decreased to a bottom and then increased later.These changes were caused by cellulase produced by Neurospora.crassa.The content of carotenoids increased with the extension of fermentation,while the content of phytic acid declined gradually and reached to steady state after 12 h.The activity of trypsin inhibitor also decresed gradually,and was completely destoryed after 48 h.(2)According to the single factor tests and response surface analysis,the optimized fermentation conditions with Neurospora crassa alone were showed as followed:fermentation temperature 30?,fermentation time 72 h,solid-liquid ratio1:3.5,inoculation amount of Neurospora crassa 1%(m/m),initial p H7.0.under this conditions,protein hydrolysis can reach 10.05%.(3)According to the single factor tests and response surface analysis,the optimized fermentation conditions with Neurospora crassa and Saccharomyces cerevisiae together were showed as followed:fermentation temperature 30?,fermentation time 74.7 h,solid-liquid ratio 1:3.0,inoculation amount of Neurospora crassa 1%(m/m),inoculation amount of Saccharomyces cerevisiae 20%(m/v).under this conditions,protein hydrolysis can reach 8.05%..(4)In unfermented soybean meal,the content of total free amino acid were 3.4mg/g,essential amino acids were 0.5 mg/g,and protein in vitro digestion rate were57.99%.After soybean meal fermented by Neurospora crassa,the total free amino acid is 47.7 mg/g,improves 13 times than that in unfermented soybean meal,and essential amino acid content is 39.8 times than that in unfermented soybean meal.The content of glutamic acid,leucine,phenylalanine,valine,histidine and tyrosine,isoleucine significantly increased.Protein in vitro digestion rate reached 95.96%,increased by 37.97%.when Neurospora crassa and saccharomyces cerevisiae together fermented soybean meal,the total free amino acid were 25.4 mg/g,also increased 6.76 times than that in unfermentated soybean meal,essential amino acids increased to 17.6 times than that in unfermented soybean meal.The content of glutamic acid,alanine,valine,leucine increased.Lysine increased 0.3 mg/g,which was significant different that lysine was not found in a single bacterium fermentation.Besides,protein content increased by 7.36%,but the protein digestibility in vitro was reduced by 23.05%.(5)Fermented soybean meal significantly decreased allergen and enhance the antioxidant capacity.The results were showed that soybean meal fermented by Neurospora crassa greatly improved its nutrition and function,and may serve as sources of protein for not weaned animals.(1)The inhibitory effect of soybean fermented by Neurospora crassa was studied by oxford cup method.The results showed that bacteriostatic ring are not transparent around oxford cup edge.So the fermented soybean meal could not inhibit growth of gram-positive staphylococcus aureus 2603 and gram-negative escherichia coli 44102.(2)SDS-PAGE electrophoresis showed that macromolecular proteins of soybean meal are degraded by fermentation.molecular weight of fermented soybean meal were less than 14.4 k Da.From Western blotting qualitative detection of allergic,there is no stripe in fermented soybean meal.So there is no antigen antibody response in fermented soybean meal.From quantitative detection of allergic reaction by the competitive inhibition of ELISA test,IC₅₀ value of soybean meal was 0.59?g/m L,IC₅₀ value of soybean meal fermented by Neurospora crassa was more than20?g/m L,IC₅₀ value of soybean meal fermented by Neurospora crassa and Saccharomyces cerevisiae was 5.28?g/m L.Protein immune reactivity of fermented soybean meal was significantly decreased.(3)In soybean meal fermented by Neurospora crassa,the total antioxidant capacity increased 1.37 mmol/g by DPPH method,the total antioxidant capacity significantly increased 10.26 mmol/g by ABTS method,the total antioxidant capacity increased 2.37 mmol/g by FRAP method;In soybean meal fermented by Neurospora crassa and Saccharomyces cerevisiae,the total antioxidant capacity increased 0.56 mmol/g by DPPH method,the total antioxidant capacity increased2.66 mmol/g by ABTS method,the total antioxidant capacity 2.34 mmol/g by FRAP method.