Fixed acidity

Fixed acidity meaning in wine

Fixed acidity represents the non-volatile acids naturally present in wine, primarily consisting of tartaric acid, malic acid, and smaller amounts of lactic acid from malolactic fermentation. These acids are considered “fixed” because they do not evaporate at normal temperatures, unlike volatile acids such as acetic acid. Measured in grams per liter (g/L) or as a percentage, fixed acidity typically ranges from 4.5 to 8.5 g/L in most wines, with white wines generally showing higher levels than reds due to malolactic fermentation reducing malic acid content. Tartaric acid is the most abundant and stable, contributing to wine’s structure and aging potential, while malic acid provides sharp, green apple-like characteristics that soften during malolactic conversion to lactic acid. Fixed acidity is crucial for wine balance, preservation, and sensory perception, working alongside pH levels to determine a wine’s overall acidity profile. Winemakers monitor fixed acidity throughout production to ensure proper balance with sweetness, tannins, and alcohol. In analytical terms, fixed acidity is calculated by subtracting volatile acidity from total acidity, providing a clearer picture of the wine’s structural backbone and potential for aging.