超声协同接枝反应改性大豆蛋白及其冻融稳定性

Graft Reaction and Freeze-thaw Stability of SPI Modified by Ultrasonic Assisted Glycosylation

采用超声波技术促进大豆蛋白-葡聚糖(SPI-D)接枝反应,提高改性产物的冻融稳定性,研究SPI质量分数、SPI∶D质量比、超声反应条件(温度、功率、时间)对接枝产物的接枝度、褐变程度和冻融循环后乳析指数的影响。结果表明:SPI质量分数4%、SPI∶D质量比2∶3、超声反应温度80℃、超声反应功率500 W、超声反应时间40 min条件下,接枝度为32.43%,褐变程度为0.322。改性产物与对照相比,经1,2,3次冻融循环后乳析指数分别降低了57.76%,75.33%,96.20%,显著提高了改性产物的冻融稳定性。由Pearson相关系数和Lorentz函数拟合得知接枝度与冻融稳定性高度相关。红外光谱分析表明发生美拉德反应。紫外光谱分析表明超声SPI-D的分子结构较SPI疏松,其结构朝向有利于提高冻融稳定性方向转变。

The soybean protein isolate-dextran grafts（SPI-D） were prepared by ultrasonic assisted wet glycosylation to improve the freeze-thaw stability of SPI, studied the concentration of SPI, the mass ratio of SPI to dextran, ultrasonic reaction conditions（temperature, power, time） on grafting degree, browning degree and creaming index of emulsions prepared by grafts after freezing and thawing cycle. The results showed that under the protein concentration 4%, SPI∶D ratio2∶3, ultrasonic reaction temperature 80 ℃, ultrasonic reaction power 500 W, ultrasonic reaction time 40 min, the degree of graft attained 32.43%, the degree of browning was 0.322, compared with the control SPI, the creaming index of modified products decreased by 57.76%, 75.33% and 75.33% after 1, 2, 3 times freeze-thaw cycle respectively. Pearson correlation coefficient and Lorentz function fitting indicated that degree of graft was highly correlated with freeze-thaw stability. Infrared spectrum analysis proved the happening of maillard reaction, and UV spectrum analysis showed that the molecular structure of the ultrasonic SPI-D became more loose, its structure changed to the direction which had high freeze-thaw stability.