Volatile acidity compounds are a group of acids that can be found in wine. These acids are primarily made up of acetic acid, but they can also include lactic acid, formic acid, butyric acid, and propionic acid. These compounds contribute to the overall acidity of the wine and can greatly influence its taste and aroma.
Acetic acid is the most common volatile acid found in wine. It is produced by the metabolism of acetic bacteria, which can be present in the winemaking process. Acetic acid has a distinct vinegar-like smell and taste, and if present in high concentrations, it can give the wine a sharp and unpleasant aroma. In small amounts, however, acetic acid can contribute to the complexity and character of the wine.
Lactic acid, on the other hand, is produced by lactic bacteria during malolactic fermentation. This process converts the harsher malic acid into smoother lactic acid, resulting in a softer and creamier mouthfeel in the wine. Lactic acid is less volatile than acetic acid and is generally considered a desirable component in wine, especially in red wines where it can contribute to a more rounded and balanced flavor profile.
Formic acid, butyric acid, and propionic acid are volatile acids that can also be found in wine, although in smaller amounts. Formic acid is commonly associated with a pungent and sour aroma, while butyric acid can give off a rancid or cheesy smell. Propionic acid is often described as having a slightly sweet and fruity aroma.
To measure the volatile acidity compounds in wine, various methods can be employed. The traditional Cash Still method involves steam distillation to separate the volatile acids from the rest of the wine, which are then titrated to determine the concentration. However, more modern techniques such as gas chromatography, high-performance liquid chromatography (HPLC), and enzymatic methods are now commonly used for more accurate and efficient measurements.
In my experience as a sommelier and brewer, volatile acidity compounds can greatly impact the overall quality and enjoyment of a wine. I have come across wines with excessive acetic acid that were undrinkable due to the overpowering vinegar-like aroma. On the other hand, wines with balanced levels of volatile acidity, particularly lactic acid, can exhibit a pleasant complexity and depth of flavor.
Understanding the different volatile acidity compounds and their impact on wine is crucial for winemakers and enthusiasts alike. By carefully managing and monitoring these compounds during the winemaking process, it is possible to achieve a well-balanced and harmonious wine with the desired characteristics.