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PASTA AND SEMOLINA TECHNOLOGY
of a 4-year European study (Autran, 1995; Feillet & Laignelet, 1996) have investigated the current trends in this area and in particular the problems introduced by the high-temperature drying of pasta. As far as the available methods are concerned, there still seems to be a problem with regard to quantifying T. aestivum adulteration. The conclusions were that only three of the tests (electrophoresis of the a-gliadins, RP-HPLC of a y-gliadin fraction, and the immunochemical test for friabilin) were ‘workable’ and that all the methods had problems in determining the proportion of T. aestivum present. The main areas of current activity that use proteins as markers of adulteration are the immunochemical detection of T. aestivum and in particular the continued attempted commercialisation of the antibody methods. Polyclonal antibodies were raised against unheated and heated T. aestivumspecific y- and a-gliadins (Stevenson et al., 1994) with a view to detecting their presence in pasta products. However following the use of the protein friabilin to detect T. aestivum semolina and the European Patent application by RhGne-Poulenc Diagnostics, a number of rapid test kits were developed (Boney, 1998). RhGne-Poulenc Diagnostics Technologies have since launched three antibody-based tests (Pastascan, Durotest S (for use with semolina) and Durotest P (for use with pasta; Autran et al., 1994). All are based upon detection of friabilin. Pastascan and Durotest S use ‘dipstick’ technology to produce a quick qualitative result indicating the presence or absence of T. aestivum. Durotest P, however, is designed to give a quantitative result. Cortecs Diagnostics, in collaboration with Nottingham Trent University, have also released a test kit based on the detection of a T. aestivum-specific y-gliadin. Information regarding this kit is very limited but their literature suggests a limit of detection of about 1%.As yet no information is available concerning the reproducibility, accuracy or precision of these tests. A further point that needs to be addressed for all protein-based detection methods is that little is known about the expression of particular wheat genes, and the effect that growth conditions have on the expression of the protein encoded. Recent results (G. Wiseman, unpublished observations) have shown that lines of T. aestivum are in existence which, although they have been shown to contain the D genome, appear not to express the agliadins, making them undetectable by many of the present detection methods. Therefore it would seem vital that investigations be carried out to determine if the expression of marker proteins varies from one T. aestivum cultivar to another. While such research may not be required for empirical study, it is essential when a greater precision is needed and in situations where small changes could have large implications for particular manufacturers, importers or retailers who may be adjudged to have ‘adulterated’ pasta following such an analysis. The problems and uncertainties associated with the quantification of specific proteins are a major motivation to