高压复合pH偏移预处理对大豆蛋白糖基化复合物结构及乳化性质影响

本研究运用超高压处理、碱性pH偏移处理对大豆分离蛋白（soy protein isolate, SPI）进行单独和复合处理后，将其与麦芽糊精进行糖基化反应，并测定不同预处理条件对复合物结构及乳化性质影响。结果表明，与单一超高压处理或pH偏移处理相比，高压协同碱性pH偏移处理对糖基化反应的促进效果更明显。复合处理使糖基化复合物的接枝度与褐变程度增大，二级结构由有序向无序的转变程度增大，蛋白质内部疏水基团暴露量增多，蛋白分子三级结构趋于松散。其中400 MPa高压处理协同碱性pH偏移处理对糖基化改性的促进效果最为显著，所得糖基化样品的乳化活性（31.38 m2/g）和乳化稳定性值（36.88 min）最大，分别为对照组的1.89倍和1.60倍。

Effect of high pressure combined with pH-shifting treatment on the structure and emulsifying properties of soy protein isolate glycosylation products

In this paper, high pressure treatment and alkaline pH-shifting treatment were applied individually and in combination on soybean protein isolate (SPI), and then SPI was glycated with maltodextrin. The structure and emulsifying properties of the conjugates under the different pretreatment were characterized. Different pretreatment promoted the occurrence of glycosylation, especially the effect of the pressurization-assisted pH shifting treatment was more prominent. The combined treatment increased the degree of grafting and the browning values, enhanced the transition of secondary structure from an ordered to a disordered state, facilitated the exposure of hydrophobic groups initially buried inside, and loosed the tertiary structure of protein molecule. It was found that pressurization at 400 MPa combined with alkaline pH shifting treatment has the most significant effect on promoting the glycosylation of SPI. Meanwhile, the emulsifying ability and emulsion stability reached the maximum value of 31.38 m2/g and 36.88 min, which were 1.89 and 1.60 times as that of control group.