Preparation Of Whole Soybean Milk Fermented By Compound Probiotics And Prevention Of High-fat Diet Induced Hyperlipidemia In C57BL/6 Mice With Fermented Soybean Milk

The main components of fermented soymilk are soymilk and probiotics.It has the health care function of soybeans and probiotics.Based on the single factor experiment,response surface method was used to optimize the process of probiotic fermented soymilk,and the differences in physical and chemical indexes,antioxidant capacity and storage stability between soymilk with and without soybean skin were compared.As the proportion of probiotics in fermented soymilk has a great influence on the flavor and quality of the product,a RT-PCR method for rapid detection of the proportion of two probiotics(Lactobacillus plantarum H₆,Lactobacillus paracasei Y₁₂)in fermented soymilk was established.According to the conserved region of Lactobacillus plantarum and Lactobacillus paracasei,the specific primers and probes were designed to verify the specificity,sensitivity and repeatability of RT-PCR.The final results were compared with the national standard method.In order to verify the effect of fermented soybean milk on the prevention of hyperlipidemia,this study carried out further experiments in mice.C57BL/6 mice were randomly divided into three groups:high fat diet group,normal group,probiotic intervention group and fermented soybean milk intervention group.The effects of fermented soymilk on hyperlipidemia were determined by the changes of body weight,visceral fat,lipid level and liver index,liver cell morphology and intestinal flora.The results showed that the best technological process of fermented soymilk was1:8 of water ratio,5%of bacteria,8%of sugar,37℃of fermentation temperature and6 hours of fermentation time.Under this condition,we can get the product with good organization,strong bean flavor,sweet and sour taste.Compared with the soybean milk without soybean skin,the antioxidant capacity and water retention capacity of the whole soybean milk were significantly stronger（p<0.05）,similar in dietary fiber content,p H,flavor and appearance.After 21 days storage,the content of probiotics in fermented soymilk remained unchanged,no water evolution,no pathogen detection,no significant difference in p H and acidity,and good fermentation flavor.The ratio of Lactobacillus plantarum and Lactobacillus paracasei in fermented soymilk was 4:1.The sensitivity and reliability of this method were high.The total amount of Lactobacillus in fermented soymilk was（5.5±0.26）×10⁹ CFU/m L,no difference with the national standard method（p>0.05）.The above results showed that the established real-time fluorescent quantitative PCR method could detect the proportion and content of Lactobacillus plantarum and Lactobacillus paracasei in the fermented soymilk rapidly and accurately.The results of animal experiments showed that fermented soybean milk could improve the abnormal visceral fat content and body weight caused by high fat diet（p<0.05）,increase the HDL-C level（p<0.05）,improve the MDA level（p<0.01）,decrease the total bile acid（TBA）content in serum（p<0.01）,and reduce the cell vacuolation caused by high fat diet.In the aspect of antioxidant capacity,in vitro antioxidant results showed that the ABTS⁺free radical scavenging rate of fermented soybean milk was higher than that of positive control group.In vivo antioxidant results showed that SOD and GSH levels were significantly improved（p<0.05）.At the same time,fermented soymilk maintained the species richness of intestinal flora under high-fat diet,and increased the Lachnospiraceae and Ruminocaccae related to maintaining intestinal health.In conclusion,this study optimized the technological process of fermented soybean milk,used lab self isolated Lactobacillus to ferment whole soybean milk,reduced the steps of filtering soybean dregs and removing soybean skin,obtained delicious and long-term probiotic food,established RT-RCR method for rapid and accurate identification of the proportion of Lactobacillus in fermented soybean milk,and verified that fermented soybean milk can prevent hyperglycemia from many aspects The effect of lipopathy.