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3 Methods for identifying genetically engineered foods

The use of recombinantly produced chymosin in cheese production since the end of the 1980s represents one of the first applications of genetic engineering in the food industry. The Flavr Savr tomato was the first genetically modified product entering commerce that was itself a GMO; it thus brought the consumer into close contact with new plant technology. Since then, at least 27 other genetically engineered agricultural crops have been approved.

The ever-increasing number of approvals granted spurred strong interest in developing methods for identifying GMOs in food. The sceptical attitude prevalent in the populations of certain European countries (especially the German-speaking populations) towards gene technology have reinforced interest in detection methods. The availability of suitable identification procedures is necessary also for various food control activities, such as the observance of regulations on the labelling on GMOs and of regulations with respect to seed certification. The requirements on the specificity of detection methods will increase significantly with the number of distinct products available, the appearance of mixtures of distinct GMO products and increased processing of such products or complex mixtures.

Almost the entire first generation of detection methods is based on techniques applying the polymerase chain reaction (PCR) (Saiki et al., 1985; Mullis and Falloona, 1987). Although other methods may be suitable for certain tasks, their range of application tends to be much more limited than the PCR. This gap may decrease with more research and development in the respective areas. This report concentrates on PCR-based methods and certain experiences made with this technique in general and with special regard to the analysis of food stuffs. Alternative methods worth considering for special applications are also discussed. Numerous schemes for nucleotide-based amplification methods as depicted in Wolcott (1992), Carrino and Lee (1995) or current scientific text books are mentioned as useful background on the various techniques.