COMPARISON OF MAGNESIUM AMOUNT IN BLACK, GREEN, FRUIT, AND HERBAL TEAS

摘要

The diet is the main source of minerals and trace elements, thus exposure to dietary essential elements has a direct impact on human health. Magnesium is a major component of the bones, but furthermore it influences the nervous system and muscle activity. Therefore its needs must be met via nutrition. There is a non-negligible discrepancy between intake and requirements. So magnesium is often uptaken in form of nutrition supplements. Thus there is still an interest in the amount of magnesium in natural products, where it is supposed to vary. In this study, various commercially available tea powders (sold in bags) of different kinds of tea (black tea, green tea, fruit tea and herbal tea) were analysed for their content of magnesium. After a microwave assisted digestion with nitric acid and water at temperatures up to 220°C, the element concentrations have been measured with ICP-OES (inductively coupled plasma-optical emission spectroscopy) as it is a simultaneous, fast and reliable method with low detection limits. All samples have been prepared in duplicate. In all samples high amounts of magnesium (approx. 10 mg/g) could be found. This fact is satisfying from the nutritional point of view. No statistically significant differences were registered between the different classes of teas.