葡聚糖接枝对大豆蛋白功能特性及结构的影响

采用干热糖基化对大豆分离蛋白进行改性,研究其功能特质及结构特性。以葡聚糖和大豆分离蛋白(soy protein isolate,SPI)为原料,考察底物质量比和反应时间两个因素。结果表明:蛋白质与糖质量比2∶1,反应温度60℃时,产物接枝比较高,褐变程度中等;与SPI相比,糖基化之后大豆蛋白的溶解度提高了72.72%,乳化活性(emulsifying activity,EAI)和乳化稳定性(emulsion stability,ESI)分别提高了117.53%和134.20%。十二烷基硫酸钠聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE)表明SPI与葡聚糖发生了糖基化反应;傅里叶红外光谱(Fourier transform infrared spectroscopy,FT-IR)和荧光光谱分析表明,糖链的引入导致了大豆蛋白空间结构的变化;模拟体外消化特性结果表明,葡聚糖糖基化修饰对SPI体外消化性的改善效果不明显。

Effects of Dextran Grafting on Functional Properties and Structure of Soy Protein

Soybean protein isolate was modified by dry heat glycation to study its functional properties and structural properties.Soy protein isolate(SPI)and dextran were used as raw materials,and reacted by the Maillard reaction at different substrate mass ratios and different reaction times.The results showed that when protein to sugar mass ratio was 2∶1,the reaction temperature was 60°C,the product was grafted well and the degree of browning was moderate.Compared with SPI,the solubility of soy protein after glycation increased by72.72%,emulsifying activity(EAI)and emulsion stability(ESI)increased by 117.53%and 134.20%,respectively;sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)indicated that glycation reaction between SPI and dextran occur.Fourier transform infrared spectroscopy(FT-IR)and fluorescence spectroscopy analysis showed that the introduction of sugar chains led to changes in the spatial structure of soy protein.Glycation modification by dextran had no obvious effect on the improvement of the vitro digestion of SPI.