Screening Of Exopolysaccharide-producing Lactobacilli And Application Of Dextran In Acid In Soymilk

Lactic acid bacteria exopolysaccharides (LAB EPS) are generally regarded as safe (GRAS)organisms, therefore the EPS-producing LAB strains can be directly applied to fermented dairy products with highly stable properties in the rheology, texture and mouthfeel. LAB can be used directly in the food,so there is a wide range of research and application value.The main results are described as follows:1.4 strains of EPS producing strains were screened from the surface of commercial vegetables,named as F4, H9, H11 and H12. Strain H11 can produce 42.4 g/L of EPS in sucrose -MRS medium.Through the biochemical characteristics and sequencing analysis of these four strains, identified F4, H9 and H12 for the same strain, belong to Weissella confuse, strain H9 belong to Weissella cibaria.2. The results showed that the sucrose content was 20% and the rotational speed of 80 r/min was the best. Polysaccharide is obtained through ethanol precipitation, dialysis and lyophilization. The structure of extracellular polysaccharide H9 and H11 were analyzed by infrared spectroscopy and nuclear magnetic resonance spectroscopy. The results showed that 2 polysaccharides were a novel polysaccharide with the structure of (1?6)-?-D-Glup.3. The viscosity and antioxidant properties of fermented soymilk using strain H9 is better. Study on the stability of fermented soymilk by H9, the fermented soybean milk during storage at 25? and 4?.The research shows that the yogurt has characteristics of low acidity, high viscosity and high water retention. And 4? preserved is better than 25?.