Читать книгу Handbook of Enology, Volume 2 - Pascal Ribéreau-Gayon - Страница 22

The fixed acidity of a wine is obtained by subtracting volatile acidity from total acidity. Total acidity represents all of the free acid functions, and volatile acidity includes the volatile acid functions, both free and in salt form. Strictly speaking, therefore, fixed acidity represents the free fixed acid functions plus the volatile acid functions in salt form (mainly acetic acid in salt form).

When fixed acidity is analyzed, there is a legal obligation to correct for sulfur dioxide and carbon dioxide. In practice, however, these two compounds have a similar effect on total acidity and volatile acidity, so the difference between total acidity and volatile acidity is approximately the same, with or without correction (Ribéreau‐Gayon et al., 1982).