Monitoring of copper in clarified apple juices

The increased awareness of healthy lifestyle lead to a higher consumption and relevance of apple juice in human nutrition. Furthermore products obtained by organic farmic, i.e. growing of plants without using synthetic inputs, such as synthetic fertilizers and pesticides or genetically modified organisms, are preferred. Inorganic copper compounds being traditional fertilizers for apple trees are not considered as synthetic fertilizers, thus they are used also in organic farming for soil or foliar application. Therefore applied copper might be also reflected in the copper concentration of apple juices. The diet is the main source of trace elements and exposure to dietary trace elements has a direct impact on human health. Copper is an essential element for humans, the average content ranges from 50 to 250 mg per person. Copper being part of at least 13 enzymes plays a vital role for many organisms. Furthermore copper is necessary for the proper metabolism of iron, maintenance of connective tissue, pigmentation of skin and hair. Thus the determination of copper in commonly consumed food stuff and beverages is of concern. The upper limit concentration for copper in apple juices given in the Codex Alimentarius Austriacus is 5 mg/kg. Twenty clarified apple juice samples commercially available in Croatia and Austria were analyzed for their copper content. Prior to quantification by inductively coupled plasma – optical emission spectrometry (ICP-OES) the juices were digested by a microwave assisted digestion system using HNO3. The copper concentrations found were all below the limit of detection (17 µg/kg).