葡聚糖-大豆分离蛋白耦联接枝工艺优化及接枝产物理化特性研究

Optimization of grafting reaction process between soy protein isolate and dextran and research on physicochemical properties of conjugates

为研究条件温和、高接枝度、低褐变程度的糖接枝技术,以葡聚糖、大豆分离蛋白为原料,研究大豆分离蛋白-葡聚糖接枝物的制备工艺。选取物料比、接枝温度及接枝时间进行单因素实验;采用物料比、接枝温度及接枝时间为变量,以接枝度(DG)为响应值,通过响应面实验设计,优化糖接枝蛋白制备工艺,并进行理化特性分析。结果表明,糖接枝反应的最佳工艺条件为:蛋白∶糖(质量比)1∶1.2,接枝温度83℃,接枝时间7.3 h,此工艺条件下,接枝度可达56.38%,褐变程度为0.041。分别以聚丙烯酰胺电泳、氨基酸分析鉴定糖接枝蛋白,表明葡聚糖以共价键接枝在蛋白上。糖接枝蛋白在pH为7.0处的溶解性与原蛋白相比提高40.48%;乳化活性和乳化稳定性明显提高,分别比原蛋白提高69.76%和62.11%。

Dextran（DEX） and soy protein isolate（SPI） were used as materials to study the preparation technology of SPI-DEX conjugates in order to research conjugation technique with the mild condition,high grafting degree and low browning degree.The material ratio,grafting temperature and grafting time were selected as factors to carry out the single factor experiment. The response surface method was applied to optimize technical parameters of preparation using material ratio,grafting temperature,grafting time as variables,and degree of grafting as response value.The physicochemical properties were analyzed on SPI-DEX conjugates.The results showed that the optimum parameters were the material ratio 1 ∶ 1.2,grafting temperature 83 ℃ and grafting time 7.3 h. Under this condition,the optimum parameters reached to 56.38% and the browning degree was0.041.Moreover,properties of SPI-DEX conjugates were also studied by SDS-PAGE and amino acids analysis. The results exhibited dextran grafted on the protein exactly.The solubility of the SPI-DEX at pH = 7.0 increased by 40.48% in comparison with SPI.The emulsifying activity and emulsifying stability increased by 69.76% and 62.11% compared with SPI.