Study on the detection method of six varieties of genetically modified maize and processed foods

Abstract

To detect and identify six varieties of genetically modified (GM) maize, polymerase chain reaction (PCR) assays were performed in the present study. The effect of heat treatment on the detection of the genes by the PCR methods was investigated. Maize samples were subjected to 100°C and 121°C heat treatment for different time intervals, and PCR tests were then conducted by using primers specific for the maize zein gene. Results revealed that the zein gene still could be detected by the PCR after heating at 100°C for 120 min and heating at 121°C for 30 min. In addition, the establishment of PCR assays on the identification of the six varieties of GM-maize was also evaluated. Primers specific for the inserted genes in the Event 176 (Novartis), Bt11 (Novartis), MON810 (Monsanto), T25 (AgrEvo), CBH-351 (AgrEvo), and GA21 (Monsanto) GM-maize were used to conduct the PCR assays. The detection limits for these GM-maize crops is less than 0.1% (w/w). For further understanding on whether commercially available maize materials and processed foods are mixed with GM-maize, corn middling pellets, canned whole kernel maize, frozen whole kernel maize, corn tortilla and potato chips samples were collected from the markets, and detected by the PCR methods developed in this study. Results showed that five to six varieties of GM-maize were detected in the corn middling pellets and corn tortilla, whereas GM-maize of the MON810 variety as well as the T25 variety were detected in canned and frozen whole kernel maize samples. Potato chips only contained GM-maize of the MON810 variety. The results of this study demonstrate that the PCR analysis is suitable for detecting maize materials and products, and that commercially available maize materials and products in Taiwan are usually mixed with different varieties of GM-maize. Meanwhile, the major product of GM-maize is the MON810 variety.