Levels of essential and non-essential metals in the raw seeds and processed food (roasted seeds and bread) of maize/corn (Zea mays L.) cultivated in selected areas of Ethiopia

The levels of metals in raw maize seeds and its processed foods (roasted seed and bread) collected from Shendi, Finote Selam and Debre Tabor (Ethiopia) were determined by flame atomic absorption spectrometry (major metals) and graphite furnace atomic absorption spectrometry (trace and heavy metals) after wet digestion. The concentration of the metals determined (mg/kg dry weight) were in the ranges in raw seed, roasted seed, and bread: K 1633–1935, 1753–2008, 1589–2036; Na 125–164, 137–190, 160–195; Mg 388–400, 394–411, 378–401; Ca 66.5–104, 118–178, 102–144; Cr 0.17–1.58, 0.18–1.72, 0.18–1.65; Mn 1.04–3.98, 1.09–4.60, 0.52–2.83; Fe 18.0–115, 16.5–103, 45.3–146; Co 0.41–0.49, 0.50–0.76, 0.34–0.75; Cu 0.04–1.32, 0.04–2.72, 0.05–3.12; Zn 61.7–77.6, 59.2–83.0, 108–116; Pb 0.31–2.59, 0.82–3.11, 1.55–3.41; respectively. Nutritionally, the processed maize foods are found to be better sources of minerals than the raw seeds. Maize seed samples from the three areas of Ethiopia are good sources of essential metals. Analysis of variance indicated significant differences in the levels of all the metals among the three samples means except K, Mg and Pb.