Persistence of transgenic genes and proteins during soybean food processing

The soybean is a typical legume which is used to elaborate several foods around the world. Ten imported soybean seed samples were collected and planted to identify possible genetic modifications. DNA was isolated from 20 days old seedlings. After that, PCR was carried out using the 35S, RR and cry1AB/1AS primer pairs. Nine soybean samples were identified as genetically modified. These soybeans were used to prepare six different soybean foods. During food processing, critical steps were identified; such as drastic changes in temperature and pH. A sample was taken from these critical points and from the final product for DNA extraction and PCR amplification. In most of the samples the presence of the CaMV 35S promoter and the gene cry1A was identified. In addition, presence of transgenic proteins was evaluated using ELISA-DAS assay. Presence of CP4 EPSPS proteins was detected in most of the studied soybean food samples except in yogurt and tofu. No cry1AB/1AC proteins were identified in any of the samples tested.