Changes Of Phenolic Substances In Probiotic Fermented Apple Juice And Its Lipid-lowering Effect

Based on the analysis of the changes of apple polyphenols in apple juice fermentation process,this study screened the high-activity bacteria lactic acid bacteria which were adapted to the fermentation of three kinds of apple juices from Aksu,Qinguan and Aussie apples,and used high performance liquid chromatography.The instrument analyzes the dynamic changes of the original polyphenols in the apple juice fermentation process.The raw materials of the animal test were determined by the number of viable bacteria and the content of the polyphenol monomer having the lipid-lowering effect,and the hypolipidemic effect test of the high-fat model was carried out on the expected theoretical results.The main research contents and results are as follows:(1)Lactobacillus pentosus,Corynebacterium lactis,Lactobacillus delbrueckii subsp.lactis,Streptococcus mutan,Streptococcus pentosus and Bifidobacterium bifidum,six strains of lactic acid bacteria can reach the number of live bacteria of 1×10~7CFU/m L.The viable counts of Lactobacillus pentosus,Streptococcus mutan and Lactobacillus delbrueckii subsp.lactis reached 1×10~9 CFU/m L,and the live bacteria is Lactobacillus pentosus>Lactobacillus delbrueckii subsp.lactis>Streptococcus mutan.The survival rate of Lactobacillus pentosus and Lactobacillus delbrueckii subsp.lactis under strong acid and high bile salts were all greater than 97%.The results of determination of total phenolic content in fermented apple juice showed that the fermentation of Lactobacillus delbrueckii and Bifidobacterium bifidum had little effect on the total phenolic content of apple juice and the total phenolic content in apple juice was significantly higher than other strains after fermentation.The total phenol content of apple juice fermented by Lactobacillus delbrueckii subsp.lactis was 8.64mg/L.Through the screening of the four indicators in the first part,the Lactobacillus delbrueckii subsp.lactis,Lactobacillus pentosus and Bifidobacterium bifidum strains were obtained,of which the most acid production capacity is the Lactobacillus delbrueckii subsp.lactis strain,after fermentation 30h,fermented apple juice pH value of 3.60.(2)The apple juice was fermented by the selected three strains of lactic acid bacteria,and the samples were randomly sampled during the fermentation to extract the polyphenolic monomer substances of the samples,and the change trend of the polyphenols in the apple juice during the fermentation was analyzed.The fermentation effect of lactic acid can trigger the alternating change trend of the content of polyphenol monomer in apple juice,which decreases and picks up.The fermentation of different strains produced the representative polyphenol monomer of this strain.Among them,the fermented representative substance of Bifidobacterium bifidum was Gallic acid,and its content reached the upper limit value 91.88mg/L when it was fermented to 20h,and the fermentation representative of Lactobacillus delbrueckii subsp.lactis was Ellagic acid,which detected the maximum content value 275.90mg/L in the fermentation 16h.Phlorin is a representative polyphenol monomer of Lactobacillus pentosus,which detects the maximum limit value 190.50mg/L when fermentation 16h.(3)Mice were subjected to a gavage test using apple juice fermented by Lactobacillus delbrueckii subsp.lactis strain.The gavage is divided into three different doses,and the fermented apple juice accounts for 25%,50%,and 100%,respectively.After 31 days of oral and high-fat feeding experiments,it was found that the apple juice fermented by Lactobacillus delbrueckii subsp.lactis strain could effectively reduce the serum TC and LDL-C content and significantly increase the HDL-C content(P<0.05).High doses of fermented apple juice can significantly reduce the fat coefficient,AI value and weight gain of mice,and reduce the degree of fat degeneration of the liver.Overall,the fermented apple juice has potential application value in reducing blood fat.