Studies On Exogenous Lactic Acidbacteria Screening And The Microcapsule Technology

To select a new lactic acid bacteria with high-performance,five lactic acid bacteria are obtained from the powder of Germany alfalfa,and physiological method and 16 S rRNA method are combined to identify these lactic acid bacteria. In the early stage,the number 7 lactic acid bacteria from domestic routine silage is used as the control group to single out these exogenous lactic acid bacteria and get the qualified lactic acid bacteria,the quality of which is higher than that of conventional domestic lactic acid bacteria;with the exogenous lactobacillus plantarum used as test strains and the resistant starch as the core material filler to produce resistant starch-sodium alginate-chitosan microcapsule,PB experiment is designed to get significant factors. Under this has no effect on the encapsulating efficiency. The optimal concentration of the filler is to be studied and the particle size of microcapsule is to be measured. And finally the condition of encapsulationg was optimized by using response surface design. Then with the simulated experiment and classical constant temperature acceleration experiment(in vitro) to verify the effect of encapsulation. The findings are as follow:(1) five lactic acid bacteria,two lactobacillus plantarums(R 1 and R 5),and three Enterococcus faeciums(R 2,R 3 and R 4) are obtained from the Germany alfalfa powder;the acid producing rate and growth curve are measured and are contrasted by using conventional domestic advantage 7 strain of lactic acid bacteria,as a consequence of which strains R 1,R 5 and 7 are screened at the beginning;then experiment involving resistance to heat,resistance to low pH and the antibacterial ability tests is conducted to screen R1.(2) by means of PB experiment,four significant factors are obtained in the production of the micro-encapsulation,after which the single factor analysis is carried out. As a result,the concentration of sodium alginate is 2 %,the quality ratio of Core material and wall material is 1:6,the concentration of calcium chloride is 0.1 M and the emulsifying time is 15 min. Based on the above researches,it turns out that the optimal concentration of resistant starch is 2 % with particle size between 250-350 um;the survival rate of resistant starch-sodium alginate-chitosan microcapsule in the stimulated gastrointestinal tract digestive system reaches as much as 47.2 %,which is higher than that of the not encapsulated plant lactobacillus,sodium alginate microcapsule with a single material and the composition of sodium alginate-chitosan microcapsules.(3) the optimal actual conditions of the encapsulation by Response Surface Analysis are as follow:the bacteria/wall material ratio is 1:6,the concentration of sodium alginate is 1.9 %,the emulsifying time is 16 mins,the concentration of CaCl2 is 0.1 M;with regard to the experiment on the tolerance of the stimulated gastric juice and high bile salts respectively,the microcapsule survival rate can reach 46.3 % and 40.5 % accordingly;the release rate of artificial intestinal juice is 87.1 %;Based on the Arrhenius equation to predict that the active ingredients of microcapsules decreased 2 order of magnitudes,the effective time for the microcapsules is 72 d.