猪肉乳化香肠中大豆分离蛋白的检测

通过聚丙烯酰胺凝胶电泳法(sodium dodecyl sulfate polyacrylamide gel electrophoresis，SDS-PAGE)电泳检测猪肉乳化香肠中的大豆分离蛋白(soybean protein isolate，SPI)。结果显示，大豆蛋白主要有5条蛋白条带(β-大豆伴球蛋白中的d1、α'、β、d2亚基和大豆球蛋白的d3亚基) 能和猪肉的蛋白条带区分开；其中，获得了由α'亚基蛋白条带的光强度值与SPI质量分数计算得到的一个线性回归方程，该方程作为检测猪肉乳化香肠中SPI添加量(0.5%～10%)的标准曲线。应用得到的标准曲线预测已知SPI质量分数(7%、3%、1.5%、0.8%、0.5%)的猪肉乳化香肠，结果证明该方法具有很好的重复性(变异系数1.90%～7.01%)。同时将SPI质量分数的预测值和真实值进行线性回归分析，得到相关系数为0.98，证明了这种检测方法能应用于猪肉乳化香肠中大豆分离蛋白的定量检测。

Determination of Soybean Protein Isolate in Emulsion-type Pork Sausages

sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was used for the qualitative and quantitative analysis of soybean protein isolate (SPI) in emulsion-type pork sausages. Results showed that SPI displayed five major bands including β-conglycinin d1, α', β and d2 subunits and glycinin d3 subunit in SDS-PAGE, which could be distinguished from pork protein. A linear regression equation with band intensity as a function of SPI concentration of α' subunit in the range of 0.5%－10% was obtained for determining SPI in emulsion-type pork sausages. The prediction values of samples containing SPI at various amounts of 7%, 3%, 1.5%, 0.8% and 0.5% exhibited a high reproducibility with variation coefficients between 1.90% and 7.01%. The successful application of SDS-PAGE was also demonstrated by a high correlation coefficient of 0.98 obtained from regression analysis between the predicted and actual values of SPI in spiked emulsion-type pork sausages.