Qualitative and quantitative detection of genetically modified maize and soy in processed foods sold commercially in Brazil by PCR-based methods

Qualitative and quantitative polymerase-chain-reaction-based methods to detect genetically modified (gm) soy (RoundupReadyTM soy) and maize (Bt176 Maximizer maize; Bt11 maize, MON810 Yield Gard corn, T25 LibertyR Link maize) were applied to processed foods sold commercially in Brazil. In total 100 foods containing maize and 100 foods containing soy were analysed in 2000 and again in 2001. In 2000, 13% of the soy containing products and 8% of those containing maize were shown to consist of material derived from the corresponding genetically modified organisms. In five samples of the products containing gm soy <4% and in eight samples >4% of the soy derived material was identified as coming from gm soybeans, whereas in the case of products containing gm maize five samples of the maize derived material were found to contain <4% and three samples >4% of gm maize. In 2001, gm soy was found in 21% of the soy containing foods, and gm maize was found in 9% of the maize containing products. Eight samples of the products containing gm soy were shown to contain <4% and 13 samples >4% of gm soy, the corresponding values for gm maize were five samples <4% and four samples >4%.