Study On The Preparation Of Lactobacillus Acidophilus Microcapsules And Their Quality Evaluation

This paper used extrusion method to form Lactobacillus acidophilus microcapsules in order to improve the activity of Lactobacillus acidophilus in gastric juice and expand applications. Sodium alginate and chitosan were chosen as the wall materials to prepare fleeze-drying microcapsules.The physical-chemical properties and the storage stability of the microcapsules were also evaluated in detail.1. Lactobacillus acidophilus loaded microcapsules based on sodium alginate and chitosan have been prepared by extrusion technology, and its embedding rate were more than99.9%. The loss during encapsulation and coating was very low due to the gentle methods used. The microcapsules storage stability was considered as the standard, used single factor experiment to fix on the optimum processing technology parameters:sodium alginate concentration was2.0%, chitosan concentration was0.7%, chitosan solution pH was6.0, chitosan deacelation degree was96.8%, core:sodium alginate was1:4.2. The freeze drying technology of Lactobacillus acidophilus microcapsules were also investigated, used single factor and orthogonal experiment to fix on the best frozen desiccant type and dosage. When the concentration of skim milk and trehalose were1.5%and3%respectively, the survival rate of Lactobacillus acidophilus in the microcapsule after freeze drying was1.75×109cfu/g.3. The physical-chemical properties of wet and dried microcapsules were evaluated and observed in detail. The color of wet capsules were transparent and the dried were white. Both particle size was1-2mm. The results by SEM indicated that the dried capsules had smooth surface and network structure in the internal.4. When capsules were suspended in simulated gastric fluid (SGF) for3hours, the survival rate of Lactobacillus acidophilus in the microcapsule was over10cfu/g. The cell release from the wet and dried capsules in simulated intestinal fluid (SIF) was significantly different. After5hours suspended in SIF, the cells embed in wet capsules released completely. A time lag was observed in the early phase of the cell release from the dried capsules in SIF and the release rate increased after6hours. Complete release of the encapsulated cells in SIF was achieved after24hours.5. The cell release data from capsules in SIF (after2hours exposure to SGF) were analyzed according to the Higuchi equation, Korsmeyer-Peppas equation, and Peppas-Sahlin equation using MATLAB version R2009b. The results indicated that cells released from capsules were largely due to the polymer relaxation, not the diffusion through water-filled pores in the matrix.