Study On High Density Culture And Drying Process Of Lactobacillus Casei

As people pay more attention to healthy diet consumption, probiotics with hashealth care function are also be favored. As a preferred probiotic strain, Lactobacillus has a wide application prospect and market potential. To rapidly developing an efficient preparation technology of active agent of Lactobacillus and laying a foundation for production practice, it’s of great significant to the practice of pharmaceutical production of high activity of lactic acid bacteria. High density cultivation of Lactobacillus casei1.12.8which has an auxiliary protective effect on alcoholic liver damage was studied in this paper. It’s aimed to prepare compound Lactobacillus agent with high survival rate high viability, by optimizing the proliferation medium, choosing the suitable fermentation condition and fermentation processing for high density cultivation, conducting the research to the technology of vacuum freeze drying and spray drying.Orthogonal test was used in order to choose the optimum carbon source, nitrogen source and growth factor in proliferation medium. The results showed that2%glucose,1.5%tryptone and0.7%yeast extract were preferable for the growth of L. casei1.12.8. In this medium, the·OH and DPPH scavenging activity could reach to89.82%and77.97%when cultivated18h with37℃. Viability of L. casei1.12.8could reach to6.03×109CFU/mL under the same cultivating condition.Fermentation condition and process of L. casei1.12.8were also researched. The results of effects of gas environment, pH, neutralizer and fed-batch process on its growth showed that N2, pH5.5and20%NH3·H2O were the best fermentation condition. Supplying proliferation medium every3h and adding100mL feeding at18h were the best fermentation process. Viability of L. casei1.12.8reached to5.13×1011CFU/mL under this condition. After fermenting to18h with skim milk, acidity reached to89.12(?). The·OH and DPPH scavenging activity could reach to89.97%and79.63%.At last, the freeze and spray drying conditions were researched by single factor and response surface methods. The results show that the optimum protective agent contained109.2g g/1trehalose,19.6g/1glycerin,30.0g/1sodium glutamate and2.1g/1sodium acetate. The survival rate of L. casei1.12.8after freeze-drying was76.37%, but the activity of L. casei1.12.8was weaker than that cultivated in liquid medium before logarithmic phase. Single factor test was also used studied the effect of heat-shock condition spray drying conditions on viability of L. casei1.12.8. The results showed that50℃heat-shock treatment with30min, air temperature of120℃, and feed rate of12mL/min were the optimum spray drying processing. Under these conditions, the highest survival rate of63.90% was obtained, and nearly11.22% survival rate was improved. The moisture content was about5.90%, the-OH and DPPH scavenging activity could reached to67.85% and58.05%, respectively. After fermenting to18h with skim milk, the acidity was about82.03(?).