Qualitative and Quantitative Detection of GM Soy Grain, Soy Meal and Food Products

Abstract

This research was aimed to study the status and distributio nof GM soy grain, meal and food products derived from GM soybean and maize.  Samplings were made by collecting soy grain and meal from plant quarantines, the Department of Agriculture, some local grocery stores and food productes from private firms, supermarkets and local grocery stores in Bangkok and vicinity areas around Bangkok during January 2002 - September 2005.  Samples were then initally screened for GM grain, meal and food products by checking for the presence of 123 bp and 180 bp DNA fragements of CaMV 35S  promoter and nos terminator respectively by using PCR.  The positive samples were quantitatively analysed for 5-enol-pyruvyl-shikimate-3 phosphate synthase (DPSPS) by real-time PCR.  Results showed that the ratio of GM soy grain and meal and food products were 5.2 , 29.8 and 8.0% respectively.  Trends in the distribution of GM soy grain, meal and food products showed different patterns during the years 2002-2005.  In 2004, the ratio of GM soy grain, meal and food products sharply decreased.  When the positive samples quantitatively analysed for EPSPS, the average percentage of EPSPS contaminated in GM soy grain was the highest at 94.2%, while the contaminated level of GM soybean food products was at 3.7% which was not higher than the Thai standard level (5%).