Process Optimization And Performance Evaluation Of Bifidobacterium Microcapsules

Bifidobacterium are the dominant microorganisms in the gastrointestinal tract and play an important role in maintaining intestinal health,but they are sensitive to adverse environmental factors such as oxygen and gastric acid,and exhibit poor acid tolerance and are not easily stored.Thus,it is difficult to add it to food to reach the intestinal tract with sufficient number of live bacteria and exert probiotic effects.Curcumin is beneficial to human health,but it is insoluble in water.After oxidative degradation,it can still maintain strong antioxidant activity.After ingestion,it plays a synergistic role with bifidobacterium in maintaining intestinal health and improving body immunity.Sodium alginate microcapsules are more porous and cannot protect Bifidobacterium better during digestion and storage,while the addition of nanoparticles can reduce the porosity of sodium alginate microcapsules.Therefore,in order to protect the activity of Bifidobacterium,this experiment used the extrusion method to prepare Bifidobacterium breve microcapsules with sodium alginate and casein nanoparticles as wall materials,which can provide theoretical reference and reference for the development of Bifidobacterium breve food.The main research contents of this thesis are as follows:1.Casein nanoparticles were prepared by p H cycling method,and the physicochemical properties of casein nanoparticles were investigated by means of Dynamic Laser Scattering(DLS)and Transmission Electron Microscopy(TEM)analysis.The results showed that the most suitable casein nanoparticles for encapsulating curcumin were the combination of casein at a concentration of 1.0% and curcumin at 0.5mg/m L,at which the particle size distribution was more uniform,the Polydispersity Index(PDI)was 0.19±0.01,the average particle size was 200 nm,the potential was-17.35±0.83 m V,and the encapsulation rate of curcumin was 99.73±0.01%.2.By screening the experimental equipment parameters,the optimal experimental equipment parameters were found to be 2 M calcium chloride concentration,30 min curing time and 5 cm microencapsulator nozzle outlet to calcium chloride liquid surface distance.The oxygen-sensitive Bifidobacterium breve Pro Sci-106 was selected to prepare sodium alginate-casein nanoparticle microcapsules with sodium alginate and casein nanoparticles as wall materials.The optimal ratio of sodium alginate and casein nanoparticles was screened as 5:1,at which the encapsulation rate was 85.41±1.03%.However,under this ratio,the encapsulating rate of bifidobacterium in casein nanoparticle-sodium alginate microcapsules co-encapsulating bifidobacterium and curcumin decreased,indicating that curcumin at a certain concentration had certain antibacterial activity.After lyophilization of sodium alginate-casein nanoparticle microcapsules,porous structure appeared on the surface of microcapsules,and bifidobacteria and casein nanoparticle particles could be observed.3.After digestion in simulated gastric juice for 3 h,the survival rate of Bifidobacterium in sodium alginate-casein nanoparticle microcapsules was94.74±2.15%,which was significantly higher than that of Bifidobacterium in sodium alginate microcapsules(85.29±1.20%)and nudiobacterium in sodium alginate microcapsules(57.64±0.82%,p < 0.05).At this time,Bifidobacterium was not released in the microcapsules,the morphology and structure of the microcapsules did not change significantly,and the contents of sodium alginate and casein remained at 98%.After digestion in simulated intestinal fluid for 6 h,the survival rate of Bifidobacterium in sodium alginate-casein nanoparticle microcapsules was 58.33±1.64%,which was significantly higher than that of Bifidobacterium in sodium alginate microcapsules(41.23±1.26%)and nudiobacterium in sodium alginate microcapsules(29.61±0.50%,p <0.05).At this time,the microcapsule was broken but not completely digested,with sodium alginate and casein remaining 45.15±0.38% and 37.47±0.72%,indicating that the microcapsule could slow the release of Bifidobacterium.In addition,the storage process of sodium alginate-casein nanoparticles microcapsules showed good storage stability,and the viable bacteria count was still 7.43 lg CFU/m L when stored under 4℃ for 21 days,which was significantly higher than the viable bacteria count of sodium alginate microcapsules 6.8 lg CFU/m L(p < 0.05).In conclusion,the addition of casein nanoparticles can effectively solve the problem of sodium alginate microcapsules,and play a good protective role for Bifidobacterium breve Pro Sci-106 in sodium alginate-casein nanoparticles microcapsules and provide a scientific theoretical basis for the subsequent development of Bifidobacterium food.