| Sesamin is a food function factor with many beneficial physiological functions,which has the potential to regulate intestinal flora and promote intestinal health.Attapulgite particles are characteristic mineral clay in our country,which has good emulsification property after being modified by acid.In order to improve the stability and colon-targeting bioavailability of sustained-release sesamin in colon,p H-flora/enzyme triggered colon-targeting microcapsules were constructed based on acid-modified attapulgate-stabilized Pickering emulsion template method,combined with soy protein isolate and chitosan hydrochloride as wall materials in the present study.Moreover,the effects and mechanism of regulating intestinal flora structure and metabolites were further studied.This study provides experimental basis for the construction of colonic targeted delivery system of food functional factor,as well as the basic theory and application of regulating intestinal flora and promoting intestinal health.In this thesis,we used acid modified attapulgite as solid emulsifier,soybean protein isolate and chitosan hydrochloride as wall materials,and soybean oil and sesamin as core materials.Pickering emulsion template method was used to prepare sesamin colon-targeted microcapsules,and their physicochemical properties were determined and characterized.The release kinetics of sesamin microcapsules was studied by simulated digestion experiment in vitro.By analyzing the structure of intestinal flora and its metabolites,the promoting effect of sesamin microcapsules on intestinal health and its mechanism were studied.The main research contents and results of this paper are as follows:Firstly,Pickering emulsion was prepared by using acid-modified attapulgite particles as emulsifier and soybean oil as oil phase.The effects of attapulgite particle mass fraction,oil phase volume fraction and aqueous phase p H value on the stability of Pickering emulsion were investigated.The detection indexes mainly included emulsion type,particle size,morphology and potential.The results showed that Pickering emulsion has the strongest stability when the p H of water phase is 6.0,the mass fraction of attapulgite particle is 1.5%,and the volume fraction of oil phase is2.0%.Secondly,based on stable Pickering emulsion as template,the effects of p H,core wall ratio,wall material ratio,temperature and time of water bath on the embedding rate of microcapsules were investigated by single factor and response surface tests.The embedding rate of soybean oil was used as evaluation index to optimize the preparation technology of sesamin microcapsules.The results showed that the optimum preparation conditions were as follows: p H 6.0,core to wall ratio 1:2.0,wall to material ratio 1:1.0,water bath temperature 55℃,water bath time 3 h.Under these conditions,the maximum embedding rate of soybean oil microcapsules was82.67±0.68%.Under the optimal conditions,the embedding rate of sesame microcapsules was 71.36±0.61%,and the drug loading was 262.97±0.98 μg/100 mg.Thirdly,the basic physicochemical properties,characterization and storage stability of sesamin microcapsules were studied by laser particle size analyzer,fluorescence microscope,scanning electron microscope,infrared spectrometer,thermogravimetric and differential thermal analyzer.The results showed that sesamin microcapsules have good dispersibility,uniform particle size,The average particle size is 17.78 μm,and effective embedding of core material.Infrared spectrum analysis showed that the formation mechanism of microcapsules was the result of electrostatic recombination of soybean protein and cationic polysaccharide chitosan hydrochloride.The vitreous transformation temperature of sesamin microcapsules was 50.24℃,which showed that sesamin microcapsules had stable storage at room temperature.Toxicological study of zebra fish showed that sesamin microcapsules were safe to eat.The release curve,release kinetics equation,colonic delivery and slow release performance of sesamin microcapsules in different digestive fluids were studied by simulated gastrointestinal digestion experiments in vitro.The cumulative release rate of sesamin in gastric fluid(SGF)was 2.58±1.41%,that of sesamin in intestinal fluid(SIF)was 13.61±1.24%,and that of sesamin in colon(SCF)was 90.81±1.58%.Sesamin microcapsules were almost completely decomposed in colon wall material.According to the release data of sesamin in SCF,the release mechanism of sesamin microcapsules in SCF was fitted as Wei bull model.These results indicate that sesamin microcapsules have the properties of colonic localization and slow release.Finally,the changes of intestinal flora structure and metabolites under the intervention of sesame microcapsules were studied by using the anaerobic fermentation culture system of intestinal flora,combined with high-throughput sequencing analysis and GC-MS analysis.The results showed that sesamin microcapsules changed the p H value of intestinal environment,significantly increased the content of short-chain fatty acids,and reduced the types and contents of intestinal harmful gases.The results of high-throughput sequencing analysis showed that sesamin microcapsules significantly increased the relative abundance of intestinal Firmicutes and Lactobacillus,and significantly decreased the relative abundance of Bacteroidete,which can promote the proliferation of intestinal probiotics and regulate the structure of intestinal flora. |
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