Cereal Chem 47:720 - 731.  |  VIEW ARTICLE
Nutrient Composition of Selected Wheats and Wheat Products. VI. Distribution of Manganese, Copper, Nickel, Zinc, Magnesium, Lead, Tin, Cadmium, Chromium, and Selenium as Determined by Atomic Absorption Spectroscopy and Colorimetry.

E. G. Zook, F. E. Greene, and E. R. Morris. Copyright 1970 by the American Association of Cereal Chemists, Inc. 

Magnesium and eight trace mineral elements, manganese, copper, nickel, zinc, lead, tin, cadmium, and chromium, were determined by atomic absorption spectroscopy in 11 known wheats or wheat blends, 20 commercially prepared flours from these wheats, and 25 specially prepared products from the flours. The same minerals were determined in ten consumer products from ten different cities. There was significant variation among the five hard wheats in their content of nickel, zinc, lead, tin, cadmium, and chromium. The concentrations of all elements but lead were lower in the Baker's patent flour than in the hard wheats. Flour was the major source of manganese, copper, zinc, magnesium, and lead in breads, but only one-half or less of the chromium, nickel, tin, and cadmium in bread could be attributed to the contribution of the flour. Manganese, copper, zinc, cadmium, and chromium varied significantly in the four soft wheat samples, most of the variation being contributed by a single low mineral wheat. In general, the more highly refined short patent (cake) flours were lower in mineral content than the straight-grade and cut-off flours from the soft wheats. The concentrations of manganese, copper, zinc, and magnesium were about the same or lower and nickel, tin, cadmium, and chromium higher in the cake and crackers than in the respective flour from which they were made. Approximately 20 to 30% of the mineral content of the two durum wheat samples was recovered in the semolinas prepared from them. The mineral content of macaroni was almost entirely accounted for by the contribution of the semolinas. There was relatively small difference between the mineral content of bread prepared by conventional sponge-dough and continuous-mix procedures. Air classification vs. conventional milling had no significant effect on the mineral content of flour. Although there were significant variations in the lead, cadmium, and chromium concentrations in most of the market samples of consumer products, there was no discernible effect of geographic location on the general mineral content of these products. Whole-wheat consumer products contained greater concentrations of manganese, copper, zinc, magnesium, and chromium than did products made from white flour. The selenium content of a small group of wheat blends and products was determined by a colorimetric method. The selenium concentration of the hard wheat samples exhibited about a twofold variation, but little variation was found in the selenium content of bread.