十二烷基硫酸钠-聚丙烯酰胺凝胶电泳法测定饮料中红豆含量

Determination of red bean content in beverages by sodium dodecyl sulfate-polyacrylamide gel electrophoresis

目的建立十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE)法定量分析植物蛋白饮料中红豆成分含量的方法。方法从8个主要蛋白条带中选取一个蛋白条带作为定量标记蛋白,配制红豆标准品进行SDS-PAGE实验,用Image J软件测量特征蛋白条带的灰度面积值,得到特征蛋白条带灰度面积与红豆含量关系的标准曲线。最后以市售红豆饮料为实际样品,检验该方法对于复杂样品的实用性。结果红豆含量在3~8 g/100 mL范围内,特征蛋白条带灰度面积与红豆含量呈良好的线性关系(r~2=0.9944)。向市售样品中添加2 g/100 mL标品,得到加标回收率为99.2%,相对标准偏差为1.68%(n=3)。结论该方法为红豆饮料中红豆含量的检测提供了一个可行的手段。日后,该方法可推广应用于其他以蛋白为标志物的饮料成分的定量测定。

Objective To establish a method for quantitative analysis of red bean in plant protein beverages by sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE).Methods One of the 8 main protein bands was selected as a quantitative marker.A series contents of red bean protein standard solutions were prepared and analyzed by SDS-PAGE,and the spectrum was treated by Image J software to measure gray area values of the marker bands.A standard curve was drawn between the gray area and red bean content.Finally,the applicability of the method was tested by a real sample,a commercially available red bean beverage.Results A good linear relationship between the gray area and the red bean content was found(r 2=0.9944)in the range of 3‒8 g/100 mL.Adding 2 g/100 mL standard solution to a commercial product,the recovery rate was calculated to be 99.2%,and relative standard deviation was 1.68%(n=3).Conclusion This method provides a convenient and feasible method for the quality detection of red bean beverages.In the future,this method can be extended to apply to the quantitative determination of other ingredients in beverages with protein as markers.