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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.