Capillary electrophoresis of wheat gliadin: Initial studies and application to varietal identification

Abstract

Wheat gluten proteins have important functional properties, and are reliable indicators of genotype. They are also very heterogeneous, demanding use of powerful analytical techniques. Gel electrophoresis methods are widely used for gluten analysis, but they are labor-intensive, and their data are not easily quantified. Methods of capillary electrophoresis (CE) are now available that promise to overcome these disadvantages. We here report successful application and optimization of two CE procedures for gliadin analysis. The first procedure used 0.06 mol/L sodium borate buffer, pH 9.0, containing 200 mL/L acetonitrile + 10 g/L sodium dodecyl sulfate; separations were excellent, but reproducibility was difficult to maintain. The second buffer, 0.1 mol/L phosphate, pH 2.5, containing a linear hydrophilic polymer, overcame this problem, providing separations of gliadins that are rapid, high-resolution, automatic, and easily quantified. CE analyses of gliadin also reliably differentiate varieties of all U.S. wheat classes. CE is thus a valuable technique for gliadin analysis, complementary to other methods of electrophoresis and chromatography. CE has much potential to become a routine tool for wheat varietal identification and classification, and for prediction of quality.