大米淀粉膜的制备及其性能

大米淀粉颗粒粒径较小且均匀，在水中有较好的分散性，具有良好的成膜性并且可以在自然中降解，在食品包装、医用敷料及化妆品行业中有着广泛的应用。以大米淀粉为原料，NaOH为糊化剂，甘油为增塑剂，柠檬酸为交联剂和pH调节剂，采用流延法制备了淀粉膜。通过对淀粉颗粒的形貌观察及糊化温度、淀粉溶液的表观粘度及pH值测定、淀粉膜的力学性能、透光率及承载甘草酸二钾释放性能等的测定，研究了大米淀粉的糊化条件，柠檬酸、淀粉和甘油质量分数对淀粉膜性质的影响以及承载物质的释放情况。结果表明，大米淀粉呈光滑的多边形颗粒，直径为5~8 μm，在偏光显微镜下呈现马耳他十字结构，糊化温度范围为82.5~100.8 ℃。柠檬酸在淀粉成膜过程中会与淀粉分子相互作用，同时能够调节溶液的pH值以适应人体皮肤。淀粉质量分数越高，淀粉膜断裂伸长率越低，拉伸强度越高；甘油质量分数越高，淀粉膜断裂伸长率越高，拉伸强度越低。在甘油质量分数为3.0%时淀粉膜透光率最佳，结晶度最低。制备的淀粉膜能够承载且能高效释放抗炎物质甘草酸二钾，在护肤领域具有广泛的应用前景。

Preparation and Properties of Rice Starch Film

Rice starch particles have small and uniform particle size， good dispersibility in water and film-forming property， and can be degraded in nature. At present， starch is widely used in food packaging， medical dressings and cosmetics industries. Using rice starch as raw material， sodium hydroxide as paste， glycerol as plasticizer and citric acid as crosslinking agent and solution pH regulator， starch film was prepared by tape casting. By measuring the morphology of starch particles， the gelatinization conditions of starch particles， gelatinization temperature， apparent viscosity and pH value of starch solution， mechanical properties， light transmittance and potassium glycyrrhizinate release performance of starch film tostudy the gelatinization conditions of rice starch， the effects of mass fractions of citric acid， starch and glycerol on the properties of starch film and the release of carrier substances. The results show that the rice starch used in this paperexists in the state of dispersed particles， and the gelatinization temperature ranges from 82.5 to 100.8 ℃.Citric acid interacts with starch molecules in the process of starch film formation， and can adjust the pH value of the solution to adapt to human skin. When the concentration of starch in the starch film becomes higher， the hardness after film formation is greater. The higher the concentration of glycerol， the better the elongation at break of starch film and the worse the tensile strength. In addition， the transmittance of starch film is the best when the concentration is 3.0%， which with good light transmittance has low crystallinity. Finally， the starch film prepared in this paper can contain the effective substance dipotassium glycyrrhizinate， which can be used as a skin repair film in cosmetics.