Residues of heavy metals in wine could originate from grapes (through the soil), winemaking process, bottling and storage.
Grapes variety and age also influence heavy metal content of wines.
A major source of heavy metals in wine could also come from weathering of rocks, or from environmental pollution.
Wine is also in contact with various metals such as aluminium, steel (chromium, iron, manganese, and nickel) and brass (copper, zinc, lead, and nickel) during the wine-making process.
Various metals contribute to particular characteristics in wine such as colour, flavour and aroma.
The fermentation process is influenced by the presence of copper, iron, manganese and zinc. With the exception of zinc, these metals are also part of an important antioxidant process that prevents spoilage in wine.
HEAVY METALS DEFINITION
Heavy metals are distinguished in four functional classes:
- Class A metals are essential for life in relatively high amounts (for example iron)
- Class B includes metals that have no known biological function but are not particularly toxic at low concentrations (for example strontium)
- Class C includes metals that are essential in very low concentrations (copper, molybdenum, nickel, manganese, and zinc), but at higher than certain threshold concentrations may become toxic, and finally
- Class D includes metals that are toxic even at low levels and their biological function is unclear (cadmium, mercury, and lead)
HEAVY METALS IN EUROPE
The European Union has no laws stipulating upper limits of concentrations of undesired substances in wine. Guidance is given by the OIV (Organisation Internationale de la Vigne et du Vin).
HEAVY METALS IN GREECE
In all scientific research been held all commercial Greek wines, from different wine productions areas of Greece had concentrations of heavy metals lower than the maximum permissible levels for the trace elements in wine.