High Viscosity Yogurt Fermentation Strains Filtration And Preparation Of Bacterium Agent

Fermented dairy products are popular foods such as yogurt, lactic acid drinks, cheese and so on. They include the taste of milk rich, nutritious, digestible and absorbed, etc. With their nutritional value is constantly known by all,their requirements to people are constantly increasing. Bacteria commonly used in fermented milk are Lactobacillus rhamnosus, Lactobacillus bulgaricus and Streptococcus thermophilus. Yogurt,having pure flavor, rich in nutritional value and the more important factors are from the bacteria quality. A strain of good lactic acid bacteria must be strong, short cycle of fermentation time, unique flavor and accepted by the public, only having the above points, it can be called good bacteria. Therefore, the most important thing is to select good bacteria strain.With the increasing number of dairy factories, the traditional method of natural fermentation of yogurt has been gradually replaced by the yogurt fermentation method of high number of viable bacteria, convenient, fast and has become the first choice for the majority of the production of dairy factories. That is why one focus of this paper is the vacuum freeze-dried Lactobacillus rhamnosus Protection Technology. Through its research, we can know under what kind of conditions, the bacteria powder contains the high number of viable bacteria and yogurt flavor.This paper contains the following aspects:(1) Lactobacillus rhamnosus Breeding Techniques. From commercially available yogurt,the purpose is to select a strain of bacteria.After morphological, physiological and biochemical identification and molecular identification, we determine such a strain called Lactobacillus rhamnosus, and named NCU239.(2) Breeding Techniques of Lactobacillus bulgaricus. From commercially available yogurt,the purpose is to select five strains.After morphological, physiological and biochemical identification,we initially identify the five strains of Lactobacillus bulgaricus, named L01, L02, L03, L04, L05 respectively.(3) Breeding of Streptococcus thermophilus. From commercially available yogurt,the purpose is to select five strains.After morphological, physiological and biochemical identification, we initially identify the five strains of Streptococcus thermophilus,named S01, S02, S03, S04, S05 respectively.(4)Research of plain yogurt best ratio.Using the orthogonal experiment,the above three bacteria are used for yogurt ratio test,and the best formula is as followed:milk powder addition amount 12%, soluble sugar content 8%, Lactobacillus Bulgarieus:Streptococcus thermophilus: Lactobacillus Rhamnosusl:3:5,fermentation temperature 36℃.Under the best formula,plain yogurt flavors, organizations such as acid and so on are the best.(5) Freeze-dried Lactobacillus rhamnosus NCU239 Pretreatment Technology.16h is the best time of collecting Lactobacillus rhamnosus bacteria NCU239.When the rotation is 3500rmp/min, centrifugation time was 10min, centrifugation condition is best. (6) Freeze-dried Lactobacillus rhamnosus NCU239 Protectants Research. Using single factor experiments and the Box-Behnken response surface experiments, optimization Lactobacillus rhamnosus NCU239 vacuum freeze-drying protectants formula as follows:11.12% skim milk, trehalose 4.87%,2.96% glycerol, bacteria freeze-dried survival rate can reach 96.48%±1.27%,in line with the theoretical maximum predicted value,so it has some practical significance.(7) Streptococcus thermophilus S03 freeze-dried protectants research..Using the single factor experiment and Box-Behnken response surface experiment, optimize its formula as follows:Glycerine2.26%,Sorbitolum4.35%,Maltose8.76%, bacteria freeze-dried survival rate can reach 94.34%±1.16%,in line with the theoretical maximum predicted value,so it has some practical significances(8) Lactobacillus bulgaricus L01 freeze-dried protectants research.Using the single factor experiment and Box-Behnken response surface experiment, optimize its formula as follows:skim milk 11.22%,glycerol 4.75%,trehalodr 3.89%, bacteria freeze-dried survival rate can reach 94.16 %±1.68%,in line with the theoretical maximum predicted value,so it has some practical significance.(9) milk powder addition amount 12%, soluble sugar content 8%, Lactobacillus Bulgarieus: Streptococcus thermophilus:Lactobacillus Rhamnosus6‰,fermentation temperature 36℃.Under the best formula,plain yogurt flavors, organizations such as acid and so on are the best.(10) Study of black bean black sesame yogurt. Orthogonal test is used to determine black bean,black sesame yogurt the best technology conditions:whole milk 12%,8% sugar, the ratio of black bean to black sesame 1:1.5,2% inoculum,fermentation time 4h, the fermentation temperature 42℃.