DETECTION OF GENETICALLY MODIFIED FOODS: COMPARISON OF (DNA) EXTRACTION METHODS FROM GENETICALLY MODIFIED MAIZE AND ITS DERIVED PRODUCTS.

Abstract

This work was conducted to compare between six methods for the extraction of DNA from raw maize and its derived products. On the other hand, the method (s) that given the highest levels of DNA yields and quality will be chosen to screen and detect the genetic modification in the samples that collected from the Egyptian food market. The methods were evaluated for the extraction of DNA from maize kernels (no treatment), maize flour (mechanical treatment), maize snacks, canned maize (sweet corn), frozen maize (sweet corn), maize starch, maize extruded, popcorn, corn flacks, (mechanical, thermal and treatment). Maize snacks, corn flacks, bread with corn flour and maize starch. The quality and quantity of DNA extracted from standards, containing known percentages of GMO material and from different food products. GMO Screen 35S/Nos test kit for qualitative detection of GMO varieties in food, feed and seed was used to screen the genetic modification in the samples. The positive samples for 35S promoter and or NOS terminator were identified by standard methods that adopted by EU. All methods extracted a good DNA quality from raw materials for most of the raw materials. High pure DNA extraction kit recovered the highest levels of DNA. DNA yields for maize-derived foods generally decreased with the extent that the product had been processed. The High pure DNA extraction kits (Roch) was generally the best method for the extraction of DNA from most of the maize-derived foods. The results from screening indicated that 17 samples from investigated samples were positive for the presence of 35S promoter. 34% from the samples positive for the genetically modified maize line Bt 176.