Quality of long-time stored food wheat from the point of view of the contamination by heavy metals

In this contribution, some findings on the accumulation of certain elements (Fe, Mn, Zn, Cu, Co, Ni, Cr, Pb, Cd), with possible negative effects on human health, in long-term (13 months) stored food wheat, Triticum aestivum, L., are presented. The samples were taken from the storage depots in the Hontianske Nemce and Rybany regions, which are classified as uncontaminated with respect to the elements of interest. All samples contained variety Vlada from the 2004 harvest. The samples were milled by a laboratory mill (Brabender Quadrumat Senior) gaining four milling products: 2 low grinded flours (denoted MF 1. and 2.), milling bran (MF 3.), and grinding bran (MF 4.). Further source of samples, for comparison of contamination levels, was the highly contaminated region of Spis; cereal samples from selected localities of Kluknava agricultural company, harvest 2003. The analysis of presence of these trace elements was performed by the flame atomic absorption spectrophotometry (AAS). The reference values for the maximal acceptable levels of the concentration of the elements of interest were taken from the Food Codex of the Slovak Republic. The results indicate significant differences in the content of the risky elements in the four milling fractions. Particularly high concentrations (above limits) of Pb and Cd in the wheat were observed in the samples from the uncontaminated Rybany and Hontianske Nemce regions which were even higher than those observed for contaminated Spis region. The limits for Ni and Cr have not been exceeded. Higher above-limits concentrations of Fe, Mn, Zn, Cu, and Co have been found in all bran parts (fractions 3. and 4.) from all regions. The results have implications for choices regarding an appropriate milling technique and the subsequent processing of the particular milling fractions. It has been found/confirmed that the raw material (grain) from the long-term storage is unsuitable for whole-grain products. The results also underline the necessity of a more strict control of the deposits for the presence of certain elements in the food wheat including the so called non-risky localities in Slovakia. The research on the causes of the distribution of the elements of interest (heavy metals) into grain in the selected storage depots continues.