Bergerová E., Godálová Z., Siekel P. (2011): Combined effects of temperature, pressure and low pH on the amplification of DNA of plant derived foods. Czech J. Food Sci., 29: 337-345.The effect of food processing on the DNA integrity was studied by means of PCR amplification of soybean, transgenic MON 810 and non-transgenic maize, bean, and pea. The degree of DNA degradation was checked by PCR and visualised by agarose gel electrophoresis. The conditions of technological treatment such as temperature, pH, pressure, and their combination may negatively influence the integrity of DNA in processed foods and hence PCR detection of food components. The DNA over 300 bp was amplifiable when mild processing parameters up to 100°C were performed at approximately neutral or low acidic pH. The autoclaving (12°C; 0.1 MPa) significantly reduced the size of amplifiable DNA in the time dependant manner and that was intensified by acidic pH. The maximum amplicons length achieved for highly processed matrices was 300 bp. The major impact on the DNA integrity was exerted by the combination of pressure, temperature, and low pH.

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Godálová Z., Bergerová E., Siekel P. (2013): Effect of high temperature and pressure on quantification of MON 810 maize. Czech J. Food Sci., 31: 376-381.Maize MON 810 (Zea mays L.) is the only transgenic cultivar grown in the European Union countries and food products with its content higher than 0.9% must be labelled. Processing such as high temperature (121°C), elevated pressure (0.1 MPa), and low pH 2.25 fragmented DNA. A two order difference in the species specific gene content compared to the transgenic DNA content in plant materials used has led to false negative results in the quantification of transgenic DNA. The maize containing 4.2% of the transgene after processing appeared to be as low as 3.0% (100°C) and 1.9% (121°C, 0.1 MPa). The 2.1% amount of the transgene dropped at 100°C to 1.0% and at 121°C, 0.1 MPa to 0.6%. Determination of GMO (Genetically Modified Organism) content in processed foods may lead to incorrect statement and labelling could mislead consumers in these cases.

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