Research And Development Of Milk Beverage Fermented By Lactobacillus Paracasei PC-01 And Bifidobacterium Animalis Subsp.Lactis Probio-M8

In this study,two probiotic strains Lactobacillus paracasei PC-01 and Bifidobacterium animalis subsp.lactis Probio-M8 were used to prepare probiotic milk beverage to investigate the fermentation characteristics of probiotics and probiotic combination,and liquid chromatography-mass spectrometry was applied for comprehensively identification of the key metabolites in milk beverage during storage.The main results were as follows:1.The fermentation time of the probiotic combination could be shortened as reaching the specific pH value(lower than 3.80)and titratable acidity(180°T-200°T),which was significantly different from those of other groups(P<0.05).2.During storage(4?,10? and 25?),the probiotic milk beverage using composite probiotic trains showed no significant differences in pH values,titrated acidity,viable count of probiotics and sensory evaluation compared with those using lactobacillus paracasei PC-01 and the commercial strain.Taking the condition of 10? as an example,the change in pH values was less than 0.2,the titration acidity was less than 15°T,and the probiotic viable count for all groups were higher than 4 ×108 CFU·mL^-1 on 28-day storage.3.Bacterial strain was the main source of the differences causing non-targeted metabolic clustering.Compared with the single lactobacillus paracasei PC-01 group,the viable probiotic milk beverage with composite strains showed significant differences on 1-day storage.The pyrimidine metabolism,citric acid cycle,pentose phosphate pathway,phenylalanine metabolism,arginine biosynthesis,and butyric acid metabolism were the major metabolic pathways.During storage,the differential metabolites were mainly enriched in such pathways as interconversion of pentose and glucuronic acid,tyrosine metabolism,benzoate degradation,terpene skeleton biosynthesis,butyric acid metabolism,ascorbic acid and aldosterone metabolism,citrate cycle,alanine,aspartic acid and glutamic acid metabolism,and valine,as well as leucine and isoleucine biosynthesis.On day 21,the unique metabolites of the composite probiotic group were enriched in pyrimidine metabolism,arginine biosynthesis,citrate cycle(TCA cycle),pentose phosphate pathway,tyrosine metabolism,phenylalanine metabolism,histidine metabolism,etc.Therefore,the application of Bifidobacterium animalis subsp.Lactis Probio-M8 could promote the occurrence of amino acid metabolic pathway during fermentation,which provided innovative thoughts for the development of Bifidobacterium lactis in functional milk drinks.