Extraction and PCR analysis of soy DNA in chocolate

The manner in which to discriminate between genetically modified (GM) versus non-modified foodstuffs is based on the presence of newly introduced genes at the protein or DNA level. Current available methods are almost exclusively based on the polymerase chain reaction (PCR). These methods consist of three steps: DNA isolation, amplification of the desired DNA fragment and visualisation of the obtained amplification products. The first and crucial step is the DNA isolation. In this study three different methods are described for the isolation of DNA from chocolate, two of which are commercial kits. The results indicate that both kits, in contrast with the non-commercial method, are suitable for the isolation of DNA from chocolate, provided that the adapted PCR conditions are applied.