THE USE OF REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY TO DETECT COMMON WHEAT (TRITICUM-AESTIVUM) ADULTERATION OF DURUM-WHEAT (TRITICUM-DURUM) PASTA PRODUCTS DRIED AT LOW AND HIGH-TEMPERATURES

This investigation describes the development of an analytical method for the detection of common wheat (Triticum aestivum L.) adulteration of durum wheat (Triticum durum Desf.) pasta dried at low (60 degrees C) and high (92+78 degrees C and 100 degrees C) temperatures. Gliadin proteins were extracted in 70% (v/v) aqueous ethanol containing 1.0% (w/v) dithiothreitol and concentrated in order to maximise protein levels before analysis by reversed-phase high-performance liquid chromatography (RP-PPLC). A mixture of gamma/beta-gliadins were eluted as a single peak between 46-47 min on the common wheat pasta profiles, but were absent over the same time period on elution profiles obtained from durum wheat pasta. Adulteration was detectable at levels as low as 1-2% (w/w) for pasta dried at 60 degrees C and 92+78 degrees C, and 3% (w/w) for 100 degrees C dried pasta. Furthermore, the adulterant gamma/beta-gliadins peak was not affected substantially by common wheat intercultivar polymorphism, and the accuracy of this method was not reduced by the presence of commercially relevant levels of egg in the pasta sample.