米糠蛋白的超声改性及在亚麻籽油微胶囊中的应用研究

以溶解性、乳化活性指数和乳化稳定性为指标,优化了米糠蛋白超声改性的工艺条件。然后以改性蛋白、麦芽糊精为壁材,亚麻籽油为芯材,采用喷雾干燥法制备微胶囊粉末油脂,并研究改性蛋白对其包封效率、粒径、zeta-电位及微观结构的影响。结果表明:当超声功率密度5 W/mL、超声时间30 min、蛋白质量浓度4 g/100 mL时,米糠蛋白的溶解性、乳化活性和乳化稳定性最高,分别为79.04%、19.97m^2/g和168.25 min。此时二硫键含量降低了38.68%,表面疏水性升高了65.11%,表明蛋白结构部分展开,乳化性得到改善。添加超声改性蛋白制备的粉末油脂的包埋率最高为75.52%,复溶后其粒径分布图左移,平均粒径降低;zeta-电位升高使油滴不易聚集,提高了乳化稳定性。SEM图像显示,粉末油脂表面光滑连续并且颗粒较小,破裂现象不严重。超声改性米糠蛋白在粉末油脂中的β-转角结构含量增加,蛋白质结构发生伸展和重组,分子柔性增大,导致粉末油脂复溶后具有较高的乳化性,为开发新型微胶囊壁材奠定了基础。

Ultrasonic modification of rice bran protein and its application in flaxseed oil microcapsules

The process conditions of ultrasonic modifying rice bran protein was optimized,taking solubility,emulsifying activity and emulsion stability as indicators.The microcapsulated powder oil was prepared via spray drying process using modified protein and maltodextrin as the wall materials,flaxseed oil as the core material.Besides,the effects of modified protein on its encapsulation efficiency,particle size,zeta-potential and microstructure were studied.Results indicated that the highest solubility,emulsifying activity and emulsion stability of rice bran protein were achieved with 4 g/100 mL of protein after 30 min of ultrasound treatment with power density of 5 W/mL,being 79.04%,19.97 m^2/g and 168.2 min,respectively.The protein structure was partially expanded and the emulsbility was improved,which were illustrated by a decrease in the content of disulfide bond by 38.68%,and an increase of surface hydrophobicity by 65.11%.Moreover,higher encapsulation rate of 75.52%was obtained with the powdered-oil containing ultrasonicmodified protein.The particle size distribution was shifted to the left,while the average particle size decreased after reconstitution.Futhermore,the emulsion stability was improved by preventing the aggregation of oil droplets with a higher zeta-potential.The SEM image showed that surface of this powdered-oil was smooth,and the particles were small without severe rupture on the surface.Theβ-turn content of ultrasonicmodified protein in powdered-oil increased and the protein was stretched and restructured,which enhanced the molecular flexibility and finally resulted in better emulsifying property.This laid the foundation for the development of novol materials for microcapsules.