Preparation, Composition Changes And Laxative Activity Of Soybean Fermented By R. Coronoides

Soybean is a kind of familiar food in our daily life,which is rich in oil,protein and soy isoflavones and other nutrients.As a kind of food which has great potential of nutrition,the nutritive processing of soybean is of great significance.In this study,soybean was used as the experimental materials,it was fermented by Eurotium cristatum after crushed into soybean powder,the fermentation conditions of soybean powder by Eurotium cristatum was optimized,explored the composition change characteristic during the fermentation of soybean powder by Eurotium cristatum,and found that the Eurotium cristatum fermented soybean powder had a good effect of laxative,revealed the mechanism of the fermented soybean powder to relieve constipation.The main conclusions are as follows:(1)The single factor experiment was used to investigate the effects of five factors,including fermentation time,fermentation temperature,proportion of water,thickness of substrate,and inoculation amount,on the genistein content in fermented soybean powder,and the genistein content was measured by Liquid ChromatographySpectrometry Mass(LC-MS).According to the results of single factor experiment,the optimal conditions of fermentation time,fermentation temperature,proportion of water,thickness of soybean substrate and inoculation amount were as follows:6 days,28? 41,1 cm,1.5%.On this basis,we selected three indexes of fermentation time,adding water proportion and bean substrate thickness to carry out response surface optimization experiments.Through response surface optimization experiment,we obtained the optimal fermentation conditions:fermentation time 6.53 days,soybean substrate thickness 1.03cm,adding water ratio 3.83:1,and there are interaction between fermentation time and soybean substrate thickness,as well as between adding water ratio and soybean substrate thickness.(2)LC-MS,GC-MS,automatic amino acid analyzer and other detection methods was used to detect the variation of the content of total polysaccharides,total soluble protein,total flavonoids and soybean isoflavone,as well as the change of amino acid composition,contents of short chain fatty acids and volatile components during the process of fermented by Eurotium cristatum.It was found that the composition of soybean flour was significantly changed by the fermentation of soybean powder by Eurotium cristatum.The sugar continued to decrease during the fermentation process,and the maximum rate of decrease occurred between 0 and 6 days after fermentation.The contents of total protein and total flavonoids increased first and then decreased during the fermentation process,and reached the maximum level at the 6 day of fermentation.The volatile components were changed obviously,and the contents of alcohols were decreased,while the contents of lipids and 2-pentylfuran were increased,which improved most flavor obviously.Furthermore,the substance composition of soybean powder was monitored and compared at different time points in the process of soybean powder fermented by Eurotium cristatum and Bacillus subtilis,and the result showed that the conversion of glycosides to aglycone in the Eurotium cristatum fermented soybean powder were more completely when compared with the soybean power fermented by Bacillus subtilis,and therefore the soybean powder fermented by Eurotium cristatum may have higher biological activity then the soybean power fermented by Bacillus subtilis,At the same time,there is no iso-butyric acid and iso-valeric acid production during the fermentation of soybean powder by Eurotium cristatum,making its flavor more acceptable to people compared to Bacillus subtilis fermented soybean powder.(3)SD rats were used as experimental animals to compare the effect of soybean powder fermented by Eurotium cristatum and Bacillus subtilis on the improvement of constipation induced by diphenoxylate-induced constipation,and it was found that Eurotium cristatum fermented soybean powder had better improvement effect on constipation in rats.The smooth muscle layer and villus layer thickness were increased and the number of crypt cells was increased after the intervention of soybean powder fermented by Eurotium cristatum.According to the results of related physical and chemical indexes,fermented soybean powder by Eurotium cristatum could increase the contents of motilin(MTL),gastrin(GAS)and substance P(SP)in colon tissue,and up-regulate the expression of MUC2 gene,down-regulate the expression of AQP3,AQP4,IL-6,TNF-?,thus the constipation and colonic inflammation caused by constipation of rats were improved Furthermore,metabonomic analysis showed that Eurotium cristatum fermented soybean powder intervention mainly caused changes in linoleic acid metabolism of cecal contents,primary bile acid synthesis,taurine and sulfonic acid metabolism and other metabolic pathways,but the specific effects of these metabolic pathways on constipation remain to be further studied.In conclusion,through single factor test and response surface test optimization,the optimal fermentation conditions of soybean powder fermented by Eurotium cristatum were obtained as follows:fermentation time 6.53 d,thickness 1.03cm,solid-liquid ratio 3.83:1,fermentation temperature 28 ?,inoculation 1.5%.By monitoring the changes of the substances in the fermentation process,it was found that the conversion efficiency of glucoside type isoflavone to aglycone type isoflavone was high,the flavor was improved significantly,and there was no isobutyric acid and iso-valeric acid generate in the fermentation process.In addition,in animal experiments,Eurotium cristatum fermented soybean powder showed good defecative activity.The results of physical and chemical indexes showed that the Eurotium cristatum fermented soybean powder could relieve constipation mainly by affecting the contents of motilin,gastrin,substance P and the expression of MUC2,AQP3,AQP4 in colon tissue.Metabonomics analysis indicated that changes in linoleic acid metabolism,primary bile acid synthesis,taurine and sulfonic acid metabolism in cecal contents might be related to the occurrence and remission of constipation.This study provided a new idea for the utilization of soybean and the development of functional nutrition,provided a theoretical basis for the development and utilization of soybean powder fermented by Eurotium cristatum,and also provided a safe and healthy new way for the relief of symptoms of constipation patients.