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| Metal | Content, origin | Effects |
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| Potassium | A natural component of grape. Its concentrations in wine reflect the levels in grapevine in the final stages of berry ripening. | High K levels affect the stability of wine with respect to the potassium hydrogen L-(+)-tartrate precipitation. |
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| Calcium | A natural component of wine. The concentration of calcium in wine can be affected by the traditional practices of deacidification (CaCO3 addition) or plastering (CaSO4 addition). | Elevated calcium levels can lead in some wines to calcium L-(+)-tartrate precipitation. |
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| Aluminum | It is found in grape juice, but the concentration in both juice and wine is elevated because of the use of bentonite and to a lesser extent from contact with aluminum surfaces. | It has become apparent that aluminum is strongly complexed in wine which affects its bioavailability from one side and makes haze formation unlikely from the other side. |
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| Iron | It can be present at significant concentration in the juice of grapes, either through general environmental contamination (air borne dusts), or due to the application of fungicides in the vineyard. The reported Fe concentrations in juice range from 0.7 to 23.0 mg/L, with the highest concentrations from older studies when contamination from cast iron equipment was more common. | Above trace levels, iron plays roles: altering redox system of the wine in favor of oxidation, participating in the formation of complexes with tannins and phosphates thus resulting in instabilities.
At low concentration iron plays an important role in metabolism and fermentation processes as an enzyme activator, solubilizer, and functional component of proteins. |
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| Copper | It can be present at significant concentration in the juice of grapes, either through general environmental contamination (air borne dusts), or due to the application of fungicides in the vineyard.
During fermentation a large proportion of Cu is precipitated with yeast cells and its concentration is thus reduced significantly. | In trace amounts it is an important inorganic catalyst for metabolic activities of microorganisms. At high levels it plays an important role in catalyzing oxidation of wine polyphenols. |
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| Lead | Its concentration significantly increase in open-top vessels, in holding bins, and during pressing.
Juice and wine stored in concrete or waxed wood have significantly higher concentration of lead compared to juice and wine stored in stainless steel. Moreover fining with bentonite or filtering with diatomaceous earth contributes further to final Pb concentration, while fermentation, both primary and secondary, removed Pb. | Its effects on people are disastrous even in very small quantities. Lead can be accumulated in biological systems becoming potential contaminants mainly along the alimentary chain.
Symptoms of lead poisoning may include abdominal pain, constipation, headaches, irritability, memory problems, inability to have children, and tingling in the hands and feet. |
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