| As naturally occurring human intestinal probiotics on human health has played a role,in diet structure change greatly influenced the natural diversity of gut microbes,all kinds of diseases such as cardiovascular disease,diabetes,obesity prone to cause the people to restore the attention of the dynamic balance of gut microbes.Lactobacillus plantarum has the functions of maintaining the balance of intestinal ecological environment,inhibiting the growth of pathogenic bacteria and improving the body immunity,which is of great significance in maintaining human health and preventing and treating some diseases.In this thesis,the resistant starch with both heat resistance and prebiotic properties was used as the main wall material,and the effective encapsulation rate was used as the main index to systematically study the process and technology of constructing Lactobacillus plantarum TH103 microcapsules by spray drying method.The physical and chemical characteristics,sustained release characteristics and storage stability of the obtained TH103 microcapsules were characterized.To analyze the protective effect and mechanism of microcapsules against Lactobacillus plantarum TH103.(1)The growth curve of Lactobacillus plantarum TH103 was observed and drawn.The logarithmic growth period was from 2 h to 14h.After 14 hours,it entered the stable phase.The strain with a culture time of 12h was selected to make the bacterial suspension.At this time,the strain had strong stress resistance and sufficient quantity,which was suitable for embedding.(2)The preparation process of Lactobacillus plantarum TH103 microcapsule was optimized,and the embedding rate was taken as the index.RS3 resistant starch and whey protein isolate were selected to be combined with the bacteria for embedding,and the formula was as follows:When the air inlet temperature of spray drying was 120℃,the air inlet volume was 30%,and the wall material ratio was 10%(RS3:WPI=1:5)+6%trehalose,the viable bacteria count and embedding rate of Lactobacillus plantaruum microcapsules were 8.48±2.83x10~9CFU/g and 58.00±2.05%.(3)The physical and chemical properties of the prepared Lactobacillus plantarum TH103 microcapsules were characterized,the sustained release characteristics were studied and the storage properties were determined.The conclusions were as follows:In terms of physical and chemical properties,the microcapsules were milky powder on the macro level and spherical particles with concave surface wrinkles on the micro level.The diameter of the microcapsules was about 19μm,and the water content was 6.42%±0.59%.In terms of sustained release characteristics,microcapsules had a good effect of resistance to digestive tract stress.After the whole 8h gastrointestinal test,the number of viable bacteria in microcapsules only decreased by 0.62log CFU/g compared with the initial number of viable bacteria,and the number was maintained at 8.92log CFU/g.In terms of storage stability,the number of viable bacteria in the microcapsules did not decrease significantly in the storage at 4℃and-20℃,but decreased by 3.45log CFU/g in the storage process at 25℃.The theoretical storage period of microcapsules at 4℃is 238days.The theoretical storage period at 25℃is 29 days.(4)Evaluation of the application of Lactobacillus plantarum TH103 microcapsules in yogurt showed that the viable count of Lactobacillus plantarum TH103 microcapsules in yogurt did not decrease significantly within the 21-day shelf life of yogurt,and the viable count maintained at 9.65log CFU/g at 21 days,only decreased by 0.33log CFU/g.For brewing,the recommended optimal brewing temperature is warm water at 40℃. |
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