Transgenic raw materials in food production – Detection of transgene and heterologous protein levels (NT TR 542)

Abstract

  The aim of the project was to find out through a model case whether the threshold of 1 % GM material in foods is detectable with the present analytical methods. The transgenic barley material was homozygotized through microspore culture for production of doubled haploid (DH) plants. The transgenic and non-transgenic barley samples were malted, mashed and fermented. The produced malts, worts and beers were analyzed with respect to the transgene and heterologous protein. The detection of heterologous protein from the malted grains was successful only by immunomicroscopy. The heterologous enzyme was localized in the aleurone layer and scutellum of the transgenic malt, but no enzyme was detected in the starchy endosperm. This suggests that the heterologous protein was expressed but in very low level in the transgenic seeds. The real-time PCR proved to be repeatable and extremely sensitive for the detection of transgene. The threshold of 1 part in 1000 (0.1%) which is in the range of the legal requirements was obtainable with high confidence. Detectable DNA was also obtainable from wort, although repeated trials of DNA extraction from beer was not possible.