Reference concentrations of major, minor and trace elements in apple juices

Not only for toxicological reasons, but also for nutritional aspects the knowlegde of the mineral contents of commonly consumed beverages such as apple juice is important. The increased awareness of healthy lifestyle led to rising consumption and relevance of apple juice in human nutrition. Furthermore the change of the Austrian fruit juice guideline “Fruchtsaftverordnung” in 2004 permits supplementation of vitamins and trace elements to fruit juices. Since there is a lack of information about the mineral contents of fruit juices at the moment, the investigation of this beverage is of interest. Approximately 30 elements are recognized as essential to life. Whereas some are required in macronutrient amounts, such as Ca, K, Mg, and Na, others occur in trace or ultratrace quantities. Cu, Fe, and Zn are at the top end of this “trace” scale. Furthermore Co, Cr, Mn, and Ni have to be intaken via nutrition. Clarified apple juices commercially available in Europe were analysed for their contents of Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, and Zn. The juices were diluted 1:20 with 2% HNO3 prior to measurement by inductively coupled plasma optical emission spectrometry (ICP-OES). The reference concentration ranges calculated from the results obtained are the following: 50-120 mg/L Ca, 15-25 µg/L Cr, 200-900 µg/L Fe, 300-650 mg/L K, 20-60 mg/L Mg, 140-380 µg/L Mn, 11-24 mg/L Na, and 200-460 µg/L Zn. The contents of Co, Cu, and Ni were below the limits of detection (1.8, 4.1, and 3.0 µg/L respectively).