菜籽分离蛋白-卡拉胶轭合物-花椒精油 Pickering乳液的构建及其理化性质分析Fabrication of rapeseed protein isolate-carrageenan conjugate- pepper essential oil Pickering emulsion and analysis of its physicochemical properties

为促进花椒精油和菜籽蛋白的开发利用，采用热诱导法制备了菜籽分离蛋白（RPI）-卡拉胶轭合物纳米颗粒，并以此为乳化剂制备Pickering乳液负载花椒精油。通过单因素试验和响应面试验优化了RPI-卡拉胶轭合物-花椒精油Pickering乳液的制备条件。对制备的RPI-卡拉胶轭合物-花椒精油Pickering乳液的类型、微观结构、热稳定性、贮藏稳定性进行了表征，并考察了其抑菌活性。结果表明：RPI-卡拉胶轭合物-花椒精油Pickering乳液最佳制备条件为RPI-卡拉胶轭合物纳米颗粒添加量0.95%、花椒精油与大豆油混合物（体积比2∶ 3）添加量50.6%、水相pH 9.8，在此条件下包封率为92.34%。制备的RPI-卡拉胶轭合物-花椒精油Pickering乳液为水包油型，其在20~60 ℃范围内具有较好的稳定性，但在60 ℃以上不稳定。经过30 d贮藏，乳液乳滴粒径变化较小。乳液具有良好的乳滴特征，为稳定性提供了物理基础。与花椒精油和大豆油的混合物相比，RPI-卡拉胶轭合物-花椒精油Pickering乳液在作用受试菌42 h前具有相似的抑菌效果，但在42 h后表现出更强的抑菌效果。综上，RPI-卡拉胶轭合物-花椒精油Pickering乳液包封率较高，且具备优越的热稳定性、贮藏稳定性和抑菌活性。In order to promote the development and utilization of pepper essential oil and rapeseed protein, rapeseed protein isolate (RPI)-carrageenan conjugate nanoparticle was prepared by thermal induction method, and Pickering emulsion was prepared to load pepper essential oil from this material. The preparation conditions of RPI-carrageenan conjugate-pepper essential oil Pickering emulsion were optimized by single factor experiment and response surface methodology. The type, microstructure, thermal stability and storage stability of the prepared RPI-carrageenan conjugate-pepper essential oil Pickering emulsion were characterized, and its antibacterial activities were investigated. The results showed that the optimal conditions for the preparation of RPI-carrageenan conjugate-pepper essential oil Pickering emulsion were obtained as follows: dosage of RPI-carrageenan conjugate nanoparticle 0.95%, dosage of pepper essential oil-soybean oil mixture (volume ratio 2∶ 3) 50.6%, and aqueous phase pH 9.8. Under these conditions, the encapsulation rate was 92.34%. The prepared RPI-carrageenan conjugate-pepper essential oil Pickering emulsion was oil-in-water type, which had good stability at 20-60 ℃, but was not stable above 60 ℃. After 30 d storage, the average particle size of the emulsion changed little. The emulsions had good milk droplet characteristics, which provided a physical basis for stability. Compared with the blend of pepper essential oil and soybean oil, the RPI-carrageenan conjugate-pepper essential oil Pickering emulsion showed similar antibacterial effect within 42 h of action on the subject bacteria, but showed stronger antibacterial effect after 42 h. In conclusion, RPI-carrageenan conjugate-pepper essential oil Pickering emulsion has higher encapsulation rate and superior thermal stability, storage stability and antibacterial activity.