Capillary electrophoresis of wheat gliadin proteins and its potential for wheat varietal identification using pattern matching software

Abstract

Gliadins from 11 wheat flours were extracted with 30% ethanol and fractionated by capillary electrophoresis on a 20-µm i.d. untreated fused silica capillary using 0.1 M phosphate buffer (pH 2.5) containing polymer modifier. Capillary electrophoresis conducted at a constant current provided very good resolution and reproducibility (relative standard deviation <0.5) in mp;lt;15 min. Pattern matching of the profiles was performed with the PatMatch program to provide quantitative comparisons, using the relative mobility and intensity data for each gliadin protein. Data processing parameters, including the integration of the electrophoregram, were optimised for separation of gliadins extracted from either whole-grain or flour samples. The reproducibility and repeatability were compared using peak height and/or area percentages. The optimal window width for identifying matching gliadin peaks was 0.80–1.20% relative mobility units. Using these conditions, it was concluded that unknown varieties could be identified with a confidence level of 90–95%.