THE TRACE ELEMENT COMPOSITION OF WINE

Studies of Canadian wines have indicated that geographic origin and authenticity can be ascertained from their trace element compositions. Individual vineyards as well as regions have trace element “fingerprints”. However, wine chemistry also furnishes important information on the biogeochemical processes that control element concentrations in all vegetation. There is also information on how anthropogenic inputs impact agrifood products. Fundamental geochemical principles reflected in Goldschmidt's geochemical classification of the elements, help explain the general distribution/concentrations of elements in wines from one region. Lithophile elements form water-soluble and insoluble groups indicating that element behavior is controlled by factors affecting element solubility. Soil trace element concentrations appear to have limited impact on wine concentrations except in exceptional circumstances. A few elements such as Sr are made more-available for uptake where they are concentrated in salts (calcite) of alkaline soils in arid climates. Studies of wines from five regions across Canada indicate that average concentrations of many elements correlate with Degree Growing Days (a monitor of the amount of heat received in each region). This suggests that absolute concentrations reflect the amount of water and dissolved elements taken up by the plant in response to evapotranspiration. Warmer climates lead to more evaporation and higher concentrations for all elements, with element ratios still reflecting relative solubility of elements in soil water. Increasing Cr and Ni concentrations in wines over recent decades may reflect stainless-steel tanks and equipment used in processing. Similarly, high rare earth element, and high-field-strength element concentrations compared to other agri-food products may reflect the use of bentonite as a fining (clarifying) agent during production.