Based On Liquid Food Polysaccharide PH-responsive Bioactive Compound Delivery System And Its Release Property

As the change of consumption concept, to strengthen the design of targeting controlled release dellivery of bioactive compound, solve the unstable change of bioactive compound encountered in food processing and physiological barrier and improve the effectiveness and bioavailability of functional foods are the key problems in food science. Considering the functional stability and bioavaibility of bioactive compound, using starch and chitosan as carrier material, polysaccharide complex film coating carrier material and its target-controlled delivery system for liquid foods were designed in this thesis, which was controlled by the digestion resistibility of starch and p H-responsiveness of chitosan.The time of starch film shifting to be brittle and flaw, and the digestion resistibility of starch film were controlled by the esterification degree and the thickness of the film. The changes of structure and property in resistant starch acetate(RSA) film was investigated during food storage and simulated gastrointestinal transportion by scanning electron microscope, X-ray diffraction and dynamic mechanical analysis. In addidtion, the swelling behavior of the chitosan film in yoghurt and its p H-responsiveness in gastric fluid were controlled via modulate the molecular molar mass and thickness of chitosan film. Based on that, a suitable chitosan was found to delay bioactive compound releasing in yoghurt and improve its releasing in simulated GI tract.Through the methods of extrusion-spheronisation and fluid-bed spray coating, film-coated microparticle delivery systems for liquid food were established by RSA and chitosan, respectively. And their releasing properties during yoghurt storage and in-vitro simulated GI tract environment were obtained. It has been proven that an ideal immune peptide controlled release liquid food system could be established by RSA and chitosan complex-film carrier material.Combined the digestion resistibility of RSA and p H-responsiveness of chitosan, using RSA(degree of substitution 0.9) and chitosan(molecular weight 7.8×104g/mol) as complex-film coating materials, polysaccharide double-film coated microparticle delivery systems for liquid food was established and the releasing properties of polysaccharide double-film coated microparticles during yoghurt storage and in-vitro simulated GI transportation were investigated by different coating thickness. The results indicated that bioactive compound could achieve the storage stability in yoghurt and be released regularly in GI tract after adjusting and matching the thickness of inner RSA film and outer chitosan film. The result of in-vitro releasing test indicated that the bioactive compound release was lower than 30% before the microparticles transported to colon and 50% bioactive compound was releasing in colon when the coating weight of outer chitosan film was 6~7% and coating weight of inner RSA film was 4~5%. After that, the storage stability of this polysaccharide double-filmed coated microparticle in yoghurt and its colon-target controlled releasing in GI tract were explained by the physical model and mechanism.Furthermore, the releasing behavior and bioavailability of this system during storage and in animal digestive tract were verified and evaluated from the level of animal, cell and protein expression. By fluorescence labeling and living image, after storing for different time, yoghourt containing FITC labeled polysaccharide double-film coated microparticles was oral administrated to nude mouse. The result showed a good colon-target property of these microparticles. Compared to intraperitoneal injection or oral administration TP5 solution with the same dosage of thymopoietin(TP5), immune model rat which was oral administrated yoghourt containing TP5 polysaccharide double-film coated microparticles with different storage time possessed the higher the ratio of CD4/CD8 and Ig G expression analyzed by flow cytometry and ELISA, indicating the improvement of TP5 immunologic function.This research focused the key problems about the preparation of the targeting controlled delivery carriers and the estblishment of polysaccharide double-film coated microparticles for liquid food system. Through controlling the matching between the digestion resistibility of RSA and p H-responsiveness of chitosan, the challenge of the demond achieved simultaneously of storage stability and colon-target controlled releasing of bioactive compound was overcome and the bioavailability of immune peptide was improved. Thus, it provided a novel method and new idea for enhancing bioavailability of functional foods and designing polysaccharide controlled release carrier materials.