Definition: Fixed (acidity)

Refers to the sum of organic acids and fixed minerals in a wine that contains two types of acidity: fixed acidity and volatile acidity, known as total acidity. It is expressed in tartaric acid or g/l of sulphuric acid, depending on the country. The fixed acids in wine are, in order of importance, tartaric acid, lactic or malic acid, succinic acid and citric acid. As for fixed non-volatile minerals, they are not present in the bouquet but in the balance of a wine on the palate. The actual acidity of a wine is expressed by the pH coefficient.