Study On Preparation And Properties Of Polygonatum Polysaccharide And Inulin Synbiotin Microcapsules

Probiotics can colonize the intestinal tract to effectively regulate the intestinal microflora and perform their beneficial health functions.Prebiotics are non-digestible or low-digestible food ingredients that selectively promote the growth and activity of one or a limited number of probiotics in the intestinal tract,providing them with nutrition and protection.Probiotics and prebiotics work synergistically to produce a synbiotic preparation that can stimulate the growth of probiotics and the activity of the microbiota already present in the gut to have a beneficial effect on the host.Microencapsulation technology can protect probiotics from adverse environments such as the gastrointestinal tract,improve their storage stability,and perform the bioactive functions of probiotics effectively.In this experiment,the extrusion method and endogenous emulsification method were used to prepare Lactobacillus plantarum microcapsules,comparing their encapsulation rate,delayed release effect and storage stability,and the extrusion method with the best effect was obtained as the preparation method of synbiotics microcapsules.Sodium alginate and chitosan were used as wall materials,different ratios of inulin（IL）and Polygonatum polysaccharide（PP）were used as prebiotics,compounding Lactobacillus plantarum with prebiotics to prepare synbiotic microcapsules.Meanwhile,the physical and microbiological properties were studied,while the chocolate of synbiotic microcapsules were prepared and their microbiological properties were studied,and the following results were obtained.（1）The optimal extraction process conditions for PP were determined by response surface experiments:extraction temperature of 50°C,extraction time of 27min,material-to-liquid ratio of 1:13,and ultrasonic power of 325W.The PP obtained under these conditions was 24.23±0.51%.The detection of prebiotic activity revealed that the cell biomass was the largest and the p H decrease was the most obvious at IL:PP of 2:3,which was consistent with the results of monitoring the viable bacteria count.（2）Compared with the endogenous emulsification method,the microcapsules prepared by the extrusion method possessed superior performance:80.44±0.23%encapsulation rate,75.21±0.62%survival rate,75.78±0.19%gastrointestinal fluid survival rate,and tolerance to high temperature sterilization process（6.10±0.04lg（CFU/m L））.Therefore,the extrusion method was selected as the preparation method of synbiotic microcapsules and its optimal preparation conditions were explored:sodium alginate concentration 2%,Ca Cl₂ concentration0.3 mol/L,chitosan concentration 0.8%,and curing time 3h.The orthogonal test was optimized to obtain the following lyophilized protectant formulation:skim milk 6%,alginose8%,glycerol 4%,and lactulose 8%.（3）The prebiotic ratio（IL:PP）of 2:3 had excellent physical properties:lower water content（6.18%～7.90%）,which was more conducive to the storage of synbiotic microcapsules;better encapsulation,with the highest encapsulation rate of 92.61±0.20%;better heat resistance,with the survival rate of 69.01±0.99%.SEM results showed that the addition of chitosan made the surface of synbiotic microcapsules smooth.The SEM results showed that the surface of sodium alginate-Ca Cl₂ microcapsules became smooth,and the surface voids of synbiotic microcapsules became less compared with that of single Lactobacillus plantarum microcapsules;FTIR results showed that Lactobacillus plantarum and prebiotics were embedded in the microcapsules.（4）The prebiotic ratio（IL:PP）of 2:3 of synbiotic microcapsules possessed excellent gastrointestinal fluid tolerance:in the continuous gastrointestinal fluid simulation test,the microcapsules were more acid-tolerant and had the highest number of release in the intestinal fluid,which could play a good probiotic role in the intestinal tract.The results of separate release test study in gastrointestinal fluid showed that when released in gastric fluid,the number of viable bacteria could reach 7.57±0.05lg（CFU/m L）,and the survival rate was as high as 85.8±0.02%,with stronger acid tolerance;when released in intestinal fluid,it was found that the microcapsules were basically lysed completely within 120min,and the microcapsules had excellent ability to release in intestinal fluid.（5）The synbiotic microcapsules had excellent microbial properties:the survival rate of synbiotic microcapsules in storage at-20℃and 4℃was better than that at 25℃,which showed that low temperature was beneficial to its storage;in the antibacterial test,synbiotic microcapsules did not hinder the antibacterial activity of Lactobacillus plantarum,and the antibacterial effect on Escherichia coli was more obvious,and the antibacterial effect on Staphylococcus aureus was slightly worse but still had antibacterial effect;in the cholesterol-lowering test,It was found that microencapsulation does not encapsulate Lactobacillus plantarum is relatively closed and does not bind its cholesterol-lowering performance（the cholesterol degradation rate was 28.67±0.48%）.（6）The synbiotic microencapsulated milk/dark chocolate prepared with chocolate as a new food matrix had better gastrointestinal fluid tolerance,storage stability and sensory evaluation:the gastrointestinal fluid tolerance of synbiotic microencapsulated chocolate was higher than that of synbiotic microcapsules,and the protection of milk chocolate for Lactobacillus plantarum was stronger than that of dark chocolate;the storage performance of synbiotic microencapsulated chocolate at 4℃was better than that at room temperature,and dark chocolate was better than milk chocolate;both types of synbiotic microencapsulated chocolate had similar sensory quality to that of ordinary chocolate,while milk chocolate was more acceptable.