大豆分离蛋白与单糖、双糖、多糖共价复合物的冻融特性及结构表征

研究糖种类对大豆分离蛋白(soybean protein isolate,SPI)-糖共价复合物冻融特性的影响,以改性产物的乳化性质和乳析指数为指标,研究SPI与葡萄糖(glucose,G)、麦芽糖(maltose,M)和葡聚糖(dextran,D)共价复合产物冻融特性的变化,并分析改性产物的出油率、接枝度、傅里叶变换红外光谱、荧光光谱变化情况。结果表明,在反应温度80℃、反应时间3 h、蛋白质量分数4%、SPI与M质量比4∶1的条件下,SPI-麦芽糖共价复合物(SPI-M)的乳化活性和乳化稳定性分别是对照样品的1.41倍和1.29倍,经过3次冻融循环后,乳析指数分别降低了29.68%、28.3%、29.57%,出油率分别降低了4.8%、16.8%、22.6%,SPI-M的冻融稳定性显著提高,且SPI-M的乳化性和冻融稳定性均好于SPI-葡萄糖共价复合物(SPI-G)和SPI-葡聚糖共价复合物(SPI-D)。接枝度分析表明SPI-M的接枝度明显高于SPI-G和SPI-D的接枝度;傅里叶变换红外光谱分析表明糖分子以共价键的形式接入到SPI分子中;荧光分析表明蛋白结构发生改变。

Freeze-Thaw Properties and Structural Characterization of Covalent Complexes of Soy Protein Isolate with Monosaccharides,Disaccharides and Polysaccharides

In order to study the effect of sugar type on the freeze-thaw properties of soy protein isolate(SPI)-sugar covalent complex,this experiment examined and compared the emulsifying properties,creaming index,oiling off,degree of grafting,Fourier transform infrared(FTIR)spectra and fluorescence spectra of SPI complexes with glucose(G),maltose(M)and dextran(D).The results showed that under the conditions of reaction temperature 80℃,reaction time 3 h,protein concentration 4%,and SPI-to-M ratio 4:1,SPI-M complex was obtained whose emulsifying activity and emulsion stability were 1.41 and 1.29 times as high as those of the control sample,respectively.After one,two and three freeze-thaw cycles,the creaming index decreased by 29.68%,28.3%,and 29.57%,respectively,and the oiling off decreased by 4.8%,16.8%,and 22.6%,respectively.The freeze-thaw stability of SPI-M was significantly improved relative to the control group,and its emulsifying activity and freeze-thaw stability were better than those of SPI-G and SPI-D.The grafting degree of SPI-M was significantly higher than that of SPI-G and SPI-D.FTIR spectroscopy indicated that the sugar molecules were inserted into the SPI molecule through covalent bonds.Fluorescence analysis indicated that the protein structure changed.