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Lactobacillus acidophilus as probiotics an important role in the promotion of human health and disease prevention, and is increasingly becoming a hot dairy science research. Its prebiotic effect and its in the number of intestinal survival related, but it is very sensitive to external factors (gastric acid, bile salts, antibiotics), it is difficult to have a sufficient number of viable cells in the intestines play a role, and therefore establish the study of this subject, screening the stress tolerance of the strains to prepare a higher number of viable cells of the microcapsules, and microcapsules characteristics were studied. Characteristics of probiotic preparations required of strains for producing a strain known UV diethyl sulfate complex mutagenesis and tolerance screening, get a superior strain La4-5-2, and individual, groups and identification of physiological and biochemical experiments, the experimental results show that: La4-5-2 mutant strains to meet its species characteristics. Single factor test to determine the effect of various substances enrichment MRS medium, as well as the enrichment effect of the five growth-promoting factor for the nutritional needs of Lactobacillus acidophilus, and then selected the four kinds on La4-5-2 enrichment effect significant material, the amount of the orthogonal experiments four substances obtained the best medium ratio: 1.5% yeast extract, 1.5% beef extract, tomato juice, 15%, 20% of the cucumber juice; experimentally determined by single factor mutant La4-5-2 of the best fermentation conditions, the results show that the optimum fermentation conditions of La4-5-2: initial pH 6.0, fermentation temperature 37 ° C, the inoculum size 3%, liquid volume 55ml/250ml. Mutant strain fermentation medium and the optimum fermentation conditions, the determination of the growth curve, and determine the best time of the bacteria harvested 14h. Finally, determine the best lyoprotectant protective agent composition for skim milk 10%, 6% sucrose, trehalose, 3% sodium glutamate and 1%, La4 are 5-2, the survival rate of 73.45% can be achieved, micro La4-5-2 of the number of viable cells after encapsulation of 3.48 × 1012 cfu / g, and measuring La4-5-2 Properties of microcapsules, 70.11% survival rate in simulated gastric fluid after 3h still, so Lactobacillus acidophilus microcapsules can prove this test obtained able to withstand the damage of gastric juice; processing after 3h still 61.21% in the bile salt concentration of 0.3% solution of survival, microencapsulated La4-5- 2 can tolerate the destruction of the bile salts; after enteric measurement, found that the micro-capsules in the release of microbial cells within 50min, indicating that the microcapsules prepared by this method for enteric, be able to give the body benefit, in line with the Technical Specifications of the microcapsules.
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