The High-activity Concentrated Bifidobacterium Bifidum Yogurt Starters Made By The Vacuum Freeze-drying Technology

With the improvement of people's health ideology in China ,the healthy roles of yogurt and Bifidobacterium bifidum have been recognized.It'significant for promoting the industrial of high-activity concentrated Bifidobacterium bifidum yogurt freeze-drying starters of our own independent intellectual property rights and the rapidly development of fermented dairy product .In this paper , the high-activity concentrated Bifidobacterium bifidum yogurt freeze-drying starters are made by the technology of Vacuum Lyophilization .The Bifidobacterium bifidum's domestication of oxygen-resistant and acid-resistant capabilities and the course of Vacuum Lyophilization are the emphasis of study .After many time's domestication ,the results showed that the domesticated Bifidobacterium bifidum strain showed high oxygen-resistant and acid-resistant capabilities ,without variation .The tomato juice medium which is priceless and enough is used as the compound proliferated culture ,and the main factors of Inoculation amount Outfit fluid volume are stuied to find the effects on the proliferated culture .The results show :pH at 6.5～7.0 ; Outfit fluid volume loaded by the 4/5 of the fermentation tank ;Inoculated with 0.1%(living cell number about 106cfu/ml)and cultivated at 37℃for 12h ,the viable number reach about 7×109cfu/ml .The orthogonal experiment result showed that the optimal technology of Bifidobacteria bifidum single fermented was as follows :Initial pH of medium 7.0 ,inoculation 6% ,addition of 5% saccharose ,fermented temperature 39℃,the curd tim between 4h and 5h ,the viable number reaches 10⁹cfu/ml .The optimum centrifugal force and time of Bifidobacteria bifidum was 6000 r/min ,10min at the normal temperature ,the harvest rate was above 97% .The single-factor experiment and the orthogonal experiment were used to screening the allocation proportion of the protective additive of Bifidobacteria bifidum .The result was :mycose of 20% ,glycerol of 5% ,skim milk of 8% ;pH6.5～7.0;the optimal thickness of freeze-drying of 0.75cm ;At the end of freeze-drying ,the sample was removed after smashing to be refrigerated in the form of bags at 4℃;At the same time ,the survival rate of freeze-drying was found 80% ,the living bacterium is about 4.4×10¹⁰cfu/g .The freeze-drying starters was stabilization on the cell density of living bacteria and clabbering characteristics after conserving 6 months at 4℃,the result was good .