Studies On Highly Effective Proliferation Conditions Of LAB And The Processing Of Direct-to-Vat Cultures

Along with the improvement of the level of people's life and the health care, thefermented foods with lactobacillus was paid more and more close attention to by bothconsumers and the researchers because of their rich nutrition and pleasing taste.Generally at this moment, the researchers mostly focus their energy on the processingof DVS.In my experiment, I studied on the concentrating culture and the processing ofDVS in the following aspect:Firstly, starting from the choose of the best basic culture medium, I inoculatedStreptococcus thermophilus and Lactobacillus bulgaricus into different culturemediums together with the same amount. And finally I chose the improved TJAwhose proliferation efficiency was the best of all as the basic culture medium. Itprepared well for their concentrate culture.Secondly, for the sake of finding out their growth status and rhythm, I drew thecorresponding curves by running after for 30 hours according to pH value,OD valueand the amount of live LAB.Thirdly, by the single-factor-experiment and the orthogonal experiment, I havefound out a kind of high efficiency buffer I. It can adjust the acidity at any time andprevent autolyzation to a certain extent so that to promote their efficient growth andreduce their death.Then, by the single-factor-experiment and the orthogonal experiment, Iconfirmed to add 1.5% peptone solution, 4% carrot juice, 2% potato juice and 4%wort to TJA medium as nutrition enhancement to enrich the basic culture medium sothat to make optimized TJA. It can provide enough nutrition for the growth oflactobacillus. I also made a selection of collection method and finally chose centrifugingmethod, that is: by the speed of 3000rpm for 10min.I tried to desiccate the fermentation broth of lactobacillus by spray-dryingprocess and freeze-drying process. Then to measure the residual quantity oflactobacillus and contamination situation so that to make a comparison between them.Finally, it was approved that the freeze-drying process was better.Finally, I produced DVS by freeze-drying method. And I have also found out akind of complex freeze-drying protectant which have reduced death of lactobacillus.The protectant was made as follows: I took degreased milk as solvent, and addingmonosodium glutamate for 20g/L, glycerol for 30 mL/L, Vitamin C for 20g/L, That isthe complex freeze-drying protectant. It was used for a dosage of three times of thevolume of the mud.