To determine GM foods, PCR (Polymerase Chain Reaction) based methods, commercial kits, bio-sensors, microchips and other methods are used.

PCR Based Methods: The most important steps in this method are; isolation of DNA, purification of DNA and preparing samples. The main methods of PCR are PCR-ELISA, Real-time PCR, Doubles, Multiplex PCR and quantitative PCR.
Commercial Kits: There [...]

Genetic science has been used to enhance foods nutritionally especially for poor people. Zeaxanthin riched potato, flavonoid enriched tomatoes, brassica and stearidonic acid (SDA) enriched canola ad omega-3 fatty acid and eicosapentaeoic acid (EPA) enriched soybeans are examples.
The new genetically modified crop is corn. It has been enhanced with vitamin A, C and folate. According [...]

Some Genetically Modified Foods (GMOs) include Bt genes obtained from Bacillus thuringiensis which is soil bacterium. Bt gene make foods resistant to insects.
B. thuringiensis itself has been used as an insecticide for many years and it is preferred to decrease toxic chemical usage to in USA and Europe. But nowadays, transgenic Bt corn, cotton potato, [...]