Effect Of Oligosaccharides On The Cell Number Of Probiotic Drinks

Along with the development of domestic economy and enhancement of modern consumption concept, food owning probiotic function gain much attention. Lactic acid bacteria(LAB) as one of probiotic bacterial is used and applied widely, and plays an important role in food processing and healthy consumption. The probiotic cell count shall not be less than 1.0×106 CFU/mL in shelf life, or cannot play a role of expected improvement in host’s health. Based on the research of LAB, enhance cell number of viable LAB drinks is a difficult problem in domestic research. It is urgent to solve this problem to reduce the different between domestic and foreign status. The market of viable LAB drinks in China gradually grow up, form diversification with Chinese characteristic and have multi-level consumer. There is a large demand in the viable LAB drinks market. In this test 3 kinds of viable LAB drinks sold in the market was taken to definite its quality changes in shelf-life. Probiotics were isolated and identified, and their growth characteristics were studied. Finally, this study explored the oligosaccharides on the promoting effect of viable counts in LAB drinks with the following results.(1)Quality changes to viable LAB drinks in shelf-life3 kinds of LAB drinks sold in the market was taken as the research object to determine viable counts, titratable acidity, pH, centrifugal sedimentation rate and syneresis. The results revealed that the content of LAB viable cell number fell to 2.6×107 CFU/mL from the initial 9.1×107 CFU/mL, titratable acidity increased 10 oT, pH fell 0.15, centrifugal sedimentation rate changed between 0.707%~0.773%, syneresis changed between 79.2%~80.6%. The results indicated that viable cell count of LAB drinks was much higher than 1.0×l06 CFU/mL which was regulated in a correlative Chinese standard, as it had optimum acidity and high stability.(2)Isolation and identification of LABBased on their colony morphology, staining property, physiology and biochemistry, 3 LAB strains were isolated from viable LAB drinks stocks on MRS agar plates, which were named as LP, LPC-37 and LCS, respectively. These results suggested 3 LAB strains belonged to L.casei.(3)The research of growth characteristics of L.caseiThe results showed that L.casei entered logarithmic growth phase after 6 h and arrived the end of the logarithmic growth phase after 14 h and tended to be stable after 16 h. The optimum growing temperature was 37℃ for L.casei. The optimum growing pH value was 5.0~7.0 for L.casei. The characteristics of L.casei also resisted high NaCl during fermentation.(4)Oligosaccharides were studied on the cell number of viable LAB drinksOn the single factor experiment of determining the FOS, IOS and GOS addition amount of various factors. The optimal ratio of complex oligosaccharides was obtained by orthogonal experiments: FOS 0.5%, IOS 0.7%, GOS 0.5%, the cell number increased 9.7×107 CFU/mL from 2.0×107 CFU/mL in the process of fermentation.(5)Cell number changed to viable LAB drinks in storageWhen the amounts of FOS, IOS and GOS were 0.5%, 0.7% and 0.5% respectively, the cell number of the LAB drinks fermented by L.casei was fell to 3.6×107 CFU/mL from the initial 9.7×107 CFU/mL at 4℃ in 21 days The number of viable cell number in control group were fell to 5.0×106 CFU/mL from the initial 2.0×107 CFU/mL. The group adding to the oligosaccharides made the number of viable cell number declines slowly during the storage.