Plant Mutation Breeding Of Lactobacillus And Its Application In Yogurt

Yogurt is a kind of nutritional value rich drinks,it has the finishing of intestinal,antibacterial,relieve lactose intolerance,improve constipation,lower cholesterol,cancer and other effects.Yogurt is a kind of fermented dairy products,which is very popular among the people of all countries.It has become an important part of daily food.In this paper,we mainly do the following work by using the screening of Lactobacillus:From the purchase of Sichuan pickled cabbage,northeast sauerkraut and local city sold in Chinese Cabbage by means of isolation,screening and identification of a strain of growth characteristics and better ability of acid production strain L.p-6.Through the morphological observation of the strain L.p-6 and combined with physiological and biochemical tests and 16 S rDNA full sequence analysis of the final determination of the strain L.p-6 is a plant lactobacillus.The strain L.p-6 was induced by ARTP and got a stable strain L.p-6-5 with strong acid producing ability.The addition ratio of the bacteria was determined through experiments.The contents of fermentation acidity and acetaldehyde were physical and chemical indexes,Observation and Analysis on the texture of yogurt,the effect of different strain ratio on the quality of yogurt was compared,the optimum proportion of the three strains was determined.It was found that the best quality of yogurt was obtained when the ratio of Lactobacillus to Streptococcus was 1:10:40.The fermentation conditions were optimized based on the determination of the proportion of the strains.The effects of fermentation temperature,inoculation amount and the amount of sugar added on the quality of yogurt were studied.Affect degree of the three factors on the quality of yogurt for temperature > inoculation amount > white sugar content and the optimal fermentation conditions for temperature 41 degrees,inoculation amount is 3%,sugar addition is 3%,under these conditions,the obtained yogurt sensory score up to 96 points.At this time the product acidity value is 85 ° T,pH is 4.3,acetaldehyde content is 22.48 mg/L.The effects of different fermentation conditions on yogurt fermentation system was studied.5L and 10 L fermentation tank fermentation yogurt test research to enlarge the influence of fermentation on the quality of yogurt on the basis of 200 mL yogurt bottle fermentation.It was found that the acidity of yogurt produced by the fermentation of 10 L was higher than that of the sour milk produced by the fermentation of 5L.And after the 4 degree of storage conditions of yogurt to track the acidification process,the test found that in the storage process,the acidity of yogurt increased continuously.During the storage period of 21 d,the pH of yogurt was between 4.1 ~ 3.9,and the highest titration acidity was less than 100 ° T.It was found that the acidification of fermented yogurt was weak,which had a certain significance for prolonging the shelf life of the product.