Commodities among the most common brands of corn meal (12 samples of cornflakes, 9 samples of maize flour, 6 samples of cornbased biscuits, 6 samples of maize pasta, and 4 samples of tortillas) were bought in local supermarkets in the period from May to July 2007. Sample collection was carried out every month. Cornflakes, tortillas, maize pasta and corn-based biscuits were ground thoroughly in a homogenizer, while maize flour was extracted without any pre-treatment.