Acid degradation in wine is a natural process in which the sharp and lively acidity of the wine is gradually broken down. This process is also known as malolactic fermentation and takes place after alcoholic fermentation.
Malolactic fermentation occurs when lactic acid-degrading bacteria, in particular the species Oenococcus oeni, convert malic acid present in the wine into softer lactic acid. The bacteria use the malic acid as a source of energy, and carbon dioxide and lactic acid are produced during this metabolic process.
Acid reduction has several effects on the wine. Firstly, it leads to a reduction in the sharp malic acid and an increase in the softer lactic acid content. This makes the wine milder and rounder in taste, which contributes to a pleasant balance of flavors.
Secondly, acid degradation helps to stabilize the wine, as lactic acid is more stable than malic acid and is less susceptible to undesirable chemical changes. This is particularly important in the storage and ageing of wines, as a stable pH helps to maintain the quality and sensory characteristics of the wine over time.
Acid degradation can be both spontaneous and controlled. In some wines, malolactic fermentation takes place naturally, while in others specific measures are taken to promote or control acid degradation. This can be done by adding malolactic bacterial cultures or by increasing the temperature and pH value of the wine.
Not all wines can undergo malolactic fermentation. Some wine styles, such as fresh, sparkling white wines or certain sparkling wines, should have a higher acidity and therefore acid degradation is avoided in their production.
In principle, acid reduction is an important process in winemaking that contributes to the development of flavour and stabilization of the wine. It can change the character of the wine and give it a pleasant balance of flavor. Control over acid degradation allows winemakers to achieve the desired style and quality of wine.
