Study On Preparing Technology Of The Lactobacillus Caseiei Direct Vat Set

In order to development of Lactobacillus caseiei direct investment set an d provide convenience for production of dairy products and fermented meat, L actobacillus casei was used as the bacteria to research on the optimal growth environment and optimize of Lactobacillus caseiei multiplication medium by Bo x-Benhnken experiment. Treatment of freeze drying for preservation and optimiz e the composition of the freeze protective agent.The main results are as follow1.Activiating the Lactobacillus caseiei and selecting the best basis of Lact obacillus caseiei medium is the MRS broth medium; discussing the optimal cul ture conditions:temperature35℃, the best quantity of5%, initial pH7.0OD value by measuring the culture medium to map the growth curve of Lactobacil lus caseiei, found that Lactobacillus caseiei cultured in quiet place after24h in to the plateau,27h after enter the rest phase.2.The MRS agar was used as the basic medium for optimization of Lacto bacillus caseiei multiplication medium by single factor experiments and Box-Be nhnken experiments. The result showed that the optimum culture conditions we re as follow:the optimum culture medium components were as follow:mixed su gar(glucose: lactose=1:1)3.77%, yeast extract powder1.49%, soybean milk3.96%.The viable cells concentration of train Lactobacillus caseiei could reach2.81×1012CFU/mL with the optimized medium and culture conditions,which wa s8.21fold higher than in MRS.3. Optimizing the Lactobacillus caseiei freeze-dried protective agent compo sition by Plackett-Burman design,the steepest grade test and Box-Benhnken exp eriments.The result showed that the freeze-dried protective agent were as folio w:glycerol3.5%, soybean oligosaccharides0.4%,ascorbic acid0.08%,skimmed milk7.5%. Under this condition, re-watering freeze-dried powder’s OD value was1.678.The viable cells concentration of freeze-dried powder could reach8.78×1012CFU/mL,the survival rate of Lactobacillus caseiei after vacuum freez e-dried reached79.10%.4.Bacteria powder’s living bacteria number remained at12times square m agnitude at4℃and pressure during70days storage.The clotting time and titr ation acidity change trend of fermented milk were little which indicates that th e fermentation performance of bacterial powder stability.