| Bifidobacteria are widely present in the digestive system of humans and animals,and are one of the dominant flora of the human healthy intestine,with various probiotic effects such as cholesterol-lowering,tumor suppression,immune regulation,delaying aging and regulating the composition of intestinal flora.However,some Bifidobacteria are sensitive to stomach acid and other adverse environments,and their viability decreases dramatically after passing through the stomach and upper part of the small intestine,resulting in a significant decrease in the number and vitality of microorganisms entering the intestine,making it difficult for them to play a better probiotic role.Using microencapsulation technologycan play a better protective effect on Bifidobacterium,enhance its resistance to external adverse environment,control its release time and location,reduce its loss in storage and transportation,improve the survival rate of the strain,and extend the shelf life.In this thesis,Bifidobacterium breve BX-18 JZ isolated from the feces of healthy infants was used as the research object,and the microencapsules of Bifidobacterium breve were prepared by Microencapsulation Granulator B-390 with sodium alginate and soybean isolate as the composite wall material,and the optimal preparation process was determined by optimizing the concentration of sodium alginate,soybean isolate,calcium chloride,curing time and core-to-wall ratio,and the morphology was observed.Evaluate its properties such as resistance to vacuum freeze-drying,acid resistance,enteric solubility,tolerance to continuous gastrointestinal fluid and storage stability to provide some data support for the development of microencapsulation technology in industry.The main results are as follows:The optimal production process parameters for the microencapsules of Bifidobacterium breve were obtained by single-factor and orthogonal tests as follows:sodium alginate concentration of 1.8%,soybean isolate concentration of 2.5%,calcium chloride concentration of 1.5%,curing time of 40 min,and core-to-wall ratio of 1:1.The microencapsules prepared by this process showed an encapsulation rate of 90.76%.The Bifidobacterium breve microencapsules prepared according to the best production process had a round shape,less surface folds and pores,no adhesion or trailing.After vacuum freeze-drying,the survival rate of Bifidobacterium breve microencapsules reached 97.64%,which was 27.97%higher than that of the unembedded group.After treatment in artificial simulated gastric juice for 2 h,the survival rate could reach 83.58%,which was 33.20%higher than that of the unembedded group.After 60 min of treatment in artificial simulated intestinal fluid,the bacteriophage was released completely.The survival rate of the strain after continuous gastrointestinal fluid treatment reached 75.21%,which was significantly higher than that of the unembedded group(37.25%).The survival rate of Bifidobacterium breve microencapsules reached 66.67%after storage at 4℃for 28 d,and the number of viable bacteria reached 5.1×10~9CFU/m L.When it was placed under 25℃,the viable count still reached 9.0×108 CFU/m L.The storage temperature was increased to 37℃,the viable count of the encapsulated group was higher than that of the unencapsulated group,reaching 6.95×10~4CFU/m L.This indicates that Bifidobacterium breve BX-18 JZ could improve its storage stability after encapsulation.This project used microencapsulation granulator B-390 to prepare Bifidobacterium breve composite microencapsules,the preparation conditions are mild,the embedding rate is high,and the prepared particles are complete,which can provide some data support for the preparation and development of composite microencapsules in industry. |
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