Mineral Concentrations in Cow's Milk from the Canary Island

Concentrations of selenium (Se), iron (Fe), copper (Cu), zinc (Zn), sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg) were determined in samples of raw and sterilized cow's milk. The following mean concentrations (and ranges) were recorded in raw cow's milk: Se (μg/L), 16.44 (6.8–28.6); Fe (mg/L), 0.515 (0.19–1.00); Cu (mg/L), 0.076 (0.03–0.16); Zn (mg/L), 4.41 (2.3–6.6); Na (mg/L), 534.1 (278–870); K (mg/L), 1424 (1035–1874); Ca (mg/L), 1653 (1196–2236); Mg (mg/L), 113.9 (71.5–159.4). The sterilized cow's milk showed mean concentrations of Fe (0.170 mg/L) and Zn (3.06 mg/L) significantly lower than the concentrations observed in raw cow's milk; however, the mean concentrations of Se (14.90 μg/L) and Cu (0.110 mg/L) were similar and significantly higher than in raw cow's milk, respectively. No significant differences for Na, K and Mg were observed between the mean concentrations in raw and sterilized cow's milk. An important contribution to the daily intake of Ca and K for Canarian people due to the consumption of cow's milk was observed. Moderate amounts of Mg and Na, and smaller amounts of Zn and Se are also supplied. Our data for the mineral concentrations in cow's milk were within normal intervals of concentration described in the literature. The concentrations of Fe, Cu, Na, K and Ca in raw cow's milk remained approximately constant during the 12 months sampled. In contrast, the Se, Mg and Zn concentrations varied significantly with the climatic season, presenting the lowest mean concentrations during autumn.