Abstract:To improve the tolerance to gastrointestinal fluid and release performance of Lactobacillus plantarum，synbiotic microcapsules were prepared by extrusion method with L.plantarum and prebiotics（inulin and Polygonatum polysaccharide）at different mass ratios as the core materials and sodium alginate and chitosan as the wall materials.The optimal preparation conditions of the microcapsules were determined by single factor and orthogonal experiments with the embedding rate，survival rate，storage stability，tolerance to gastrointestinal fluid，and release rate as evaluation indicators.The results showed that the prebiotics at different mass ratios all had synergistic effect on the growth of L.plantarum.The preparation conditions of the microcapsules were optimized as sodium alginate of 2%，CaCl2of 0.3 mol/L，chitosan of 0.8%，and curing for 3 h.Under these conditions，the embedding rate of the microcapsules without prebiotics reached 80.44%.When the mass ratio of inulin to Polygonatum polysaccharide was 2 ∶3，the embedding rate was the highest（92.61%），and the survival rate of L.plantarum after freeze-drying was also the highest，reaching 81.44%.The experiment with simulated gastrointestinal tract in vitro showed that the embedded synbiotic microcapsules had a significant protective effect on L.plantarum.In the continuous gastrointestinal fluid simulation experiment，the viable count of L.plantarum in the suspension dropped by 7.36 lg（cfu/mL），while that in the microcapsules by 1.81 lg（cfu/mL）to the maximum.When the mass ratio of inulin to Polygonatum polysaccharide was 2 ∶3，the survival rate of L.plantarum in gastric fluid and the release rate in intestinal fluid peaked，which indicated that the synbiotic microcapsules prepared with this mass ratio had the best release performance in gastrointestinal fluid.