Research Of Based On High Density Culture Techniques Of Probiotic Yeast Culture Conditions And Application

In order to improve and research new probiotic productive starter cultures, to improve product quality and reduce the cost of starter cultures, this experiment by Streptococcus thermophilic, Lactobacillus acidophilus and Lactobacillus casei three probiotic strains for fermentation, determine the three types of probiotic mixed bacteria in the best mixing proportion, and uses the single factor experiment and the Box-Benhnken optimization respectively of the two groups mixed bacteria high density culture conditions, and study the proportion of the two groups of mixed bacteria influence on the flavor of fermented dairy products and quality, respectively for the fermentation dairy products production, improve the quality of fermented dairy products, improve system fermented dairy products processing technology and product added value, for the development of new technology of fermented dairy products in China to provide theoretical support. The main research contents and results are as follows:1. The different proportions of probiotic fermented mixed bacteria screening. Paints and Lactobacillus acidophilus, Lactobacillus casei, Streptococcus thermophilic and10groups of different proportions of probiotic mixed bacteria growth curve, the result shows that compared with Streptococcus thermophilic:Lactobacillus casei=2:1, Lactobacillus acidophilus:Streptococcus thermophilic:Lactobacillus acidophilus=1:2:1is the highest probiotic mixed bacteria in the number of living bacterium.2. The study identified two groups of probiotic mixed bacteria culture medium optimization conditions. Skim milk, for medium, according to the OD value of bacteria liquid culture conditions. In the process of bacteria culture of carbon source, nitrogen source, temperature and the influence of the initial pH value on microbial OD value was studied. Through the single factor experiment and the Box-Benhnken response surface optimization probiotic mixed bacteria culture conditions, the results show that compared with Streptococcus thermophilic:Lactobacillus casei=2:1probiotic mixed bacteria optimum culture conditions for glucose content is3.1%, yeast extract powder adding quantity0.31%, the optimum fermentation temperature is42.9℃, the best initial pH value of6.5; Lactobacillus acidophilus:Streptococcus thermophilic:Lactobacillus acidophilus=1:2:1probiotics mixed bacteria optimum culture conditions for glucose content is1.9%, yeast extract powder adding quantity0.3%, the optimum fermentation temperature is39℃, the best initial pH value of6.5.3. The experimental study on the probiotics mixed bacteria in the practical application of yoghurt production. As sensory index, acidity, viscosity, the hydraulic and the number of living bacterium for influence factors were analyzed, and the results show that the Lactobacillus acidophilus:Streptococcus thermophilic:Lactobacillus acidophilus=1:2:lprobiotic mixed bacteria is more suitable for application in the production of solidifying yoghurt, in the form of yogurts palate with close to solidifying yoghurt in the market; Streptococcus thermophilic:Lactobacillus casei=2:1probiotic mixed bacteria is more suitable for the production of type stirred yogurt, made from sweet yogurt, moderate viscosity, yogurt peculiar flavor. Lactobacillus casei and Lactobacillus acidophilus has special good health care function, starter made of low cost.