超声辅助木瓜蛋白酶改性对米糠蛋白溶解性和乳化性的影响

Influence of ultrasound-assisted papain modification on solubility and emulsification of rice bran protein

采用超声辅助木瓜蛋白酶改性技术提高米糠蛋白溶解性和乳化性。首先米糠蛋白在超声功率密度5 W/m L、超声时间30 min、蛋白质量浓度4 g/100 m L条件下进行预处理,然后通过单因素实验优化了酶反应条件。结果表明:最佳酶反应条件为酶添加量2. 5 g/100 m L、酶反应时间3 h、pH 7、酶反应温度50℃;改性后米糠蛋白溶解性和乳化活性增强,乳化稳定性降低;改性后米糠蛋白二硫键、α-螺旋和β-转角含量减小,表面疏水性、β-折叠和无规则卷曲含量升高,表明超声辅助木瓜蛋白酶改性破坏了蛋白质空间结构,进而改善了米糠蛋白溶解性和乳化性。

Ultrasound-assisted papain modification technology was used to improve the solubility and emulsification of rice bran protein. First,rice bran protein was pretreated under the conditions of ultrasonic power density 5 W/m L,ultrasonic time 30 min and protein mass concentration 4 g/100 m L,and then the enzymatic reaction conditions were optimized by single factor experiment. The results showed that the solubility and emulsification activity of rice bran protein enhanced but emulsion stability reduced under the optimal reaction conditions of enzyme dosage 2. 5 g/100 m L,pH 7,enzymolysis temperature50 ℃ and enzymolysis time 3 h. The contents of disulfide bond,α-helix and β-turn of rice bran protein after modification decreased,and the hydrophobicity and contents of β-sheet and random coil increased. These changes indicated that ultrasound-assisted enzyme modification destroyed the spatial structure of protein,thereby improving the solubility and emulsification of rice bran protein.