| Bifidobacteria as a typical probiotics, its function of increasing the health have beenadmitted, aiming at problems in the process of storing and consuming, the studyprotected bifidobacteria by microcapsule technique to prolong the storing life ofbifidobacteria products in a certain range and reduce the loss when passing stomach andintestine.The techniques of making microcapsule by extrusion and spray-drying wereoptimized to get the best condition.Preparations of bifidobacteria microcapsules used sodium alginate as wall materialand pectin as assistant material. By the orthogonal experiments, a optimal method ofpreparation of microencapsulated by extrusion technique was screened and preparedthe microcapsule of bifidobacteria.Study the functional properties of microcapsulebifidobacteria. The result indicated: The prime directions of bifidobacteria was asfollowed: glue was 2％, glue: bacterium=1:2, sodium alginate: pectin=2:1, CaCL2 was0.3mol/L; the diameter of microcapsule was 1～2mm.The viable cell counts ofbifidobacteria was above 109cfu/g, and was of good acid-tolerant, bile salt tolerant,intestines dissolved.The survival ratio of active bifidobacteria was as high as 14.6％after60 days under 37℃and 44.9％after 60 days under 4℃.Gelatin was chosen for the wall material.The best technical conditions forspray-drying of microencapsulation of Bifidobacteria were determined according to theexperiment.The results showed that the best concentration of wall-material was 3％,inletair temperature and outlet air temperature were 105℃and 54℃～57℃respectively, inletflow rate was 360mL/h. Under the optimized conditions,the rate of productivity andsurvival bacterium were 65.7％and 53.5％respectively, the viable cell counts ofbifidobacteria was over 1010cfu/g,the diameter of microcapsule was 1～2μm. The survivalratio of active bifidobacteria was as high as 12.5％for 2hours in simulated gastric, most ofthe microencapsulation of Bifidobacteria broken down for 2 hours in simulated intestinalfluid.Study the storage stabilization of microcapsulebifidobacteria in yoghurt.The resultindicated: the microencapsuled bifidobacteria storing in carrot juicemilk decreased thesensibility to store temperature, increased the ability of acid-tolerant,improved thestability of storage and prolonged greatly the store time. Microcapsuledbifidobacteriastored in yoghurt with pH below 4.2, 40℃for 28d, the viable cell counts was still above1×108 cfu/mL, stored in yoghurt with pH equal 4.2, 20℃～30℃for 28d, the viable cell counts was still above 1×106 cfu/mL.Compared to spray-drying technique, the storagestabilization of microcapsulebifidobacteria by extrusion technique was better. |
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