Study On The Microcapsules And Nanocapsules Of Gelatin-Acacia-Tannin Containing Capsaicin

The basic principle and character of polymeric assembly were summarized in the dissertation. The properties and applications of wall and core materials, preparation methods, structure and characterization, the applications of microcapsules were reviewed in details. The capsaicin-containing microcapsules and nanocapsules of gelatin-acacia-tannin were prepared by complex coacervation, and then characterized by optical microscope, scanning electron microscope, infrared spectrum, ultraviolet-invisible spectrum and so on. It was shown that molecular assembly was suitable for the microencapsulation of sensitive medicines and natural plant extracts because it had the properties of moderate chemical reactions and easily controlled procedures. The contents of capsaicin of microcapsules and nanocapsules were determined by the convenient, rapid and practical method of vanillin-sodium nitrite colorimetry. Moreover, the assembly ratio between gelatin and acacia were measured on the basis of equal charge interaction, and the assembly mechanism was discussed in the paper. The processing factors including assembly temperature, pH, solution concentration, stirring rate, types and dosage of surfactants, tannin for preparing microspheres were optimized to a specific condition, namely pH = 4.1-4.3, assembly time about 1h, temperature from 45℃-55℃. The microcapsules and microspheres had the mean diameter of 20-30μm with good dispersion, even distribution and round shape. The emulsified effects of three types of surfactants were analyzed on the basis of the morphology and particle diameter of microcapsules and microspheres, showing that hydroxylethyl cellulose had a good performance. Stirring rate exerted an important influence on the appearance and particle size distribution of the products. When stirring rate reached 350 rpm, the microcapsules and microspheres had good size distribution and morphology. The interaction mechanism between tannin and gelatin was also discussed, proving that because of the hydrogen bond and hydrophobic interaction between tannin and gelatin, a rigid layer was created at the surface of microcapsules and microcapsules to decrease aggregation and make them have good morphology and dispersion. The nanocapsules with the mean diameter of 400-600nm were also prepared by polymeric assembly, and the mechanism difference between microcapsules and nanocapsules was investigated in the thesis. The mean microencapsulation efficiency and drug loading content of microcapsules and microspheres were 78.92% and 18.69% respectively, and the release behavior was studied in the paper.The antimicrobial effects of the microcapsuls and microspheres on the bacterium, such as Botrytis cinerea Pers., Penicillium spp., Aspergillus niger V. Tiegh, and B. squamosa J. C. Walker, were studied in the paper. It was suggested that the pH had an important effect on the inhibition effect of the products, showing that the microcapsules and microspheres had a maximal inhibition effect at pH = 5.0. With the increase of capsaicin content in the microcapsules and microspheres, the inhibition effect also rose, but showing the nonlinear relation between capsaicin content and inhibition effect. The antimicrobial effect increased during the release of microcapsules and microspheres, and the inhibition rate on the spore fermentation of Botrytis cinerea Pers. reached 69.30% after release hour about 72h. The inhibition effect of microcapsules and microspheres on these bacterium reached maximum at the temperature of 60℃. When the temperature increased, the inhibition effect decreased greatly, showing little inhibition effect at 80℃...