Malolactic conversion is a process that can occur during winemaking where tart malic acid (as found in apples) is converted into a much gentler lactic acid (as found in milk) by certain bacteria. This process can affect the taste and mouthfeel of a wine, making it smoother and creamier.


This process is often referred to as malolactic fermentation, or “MLF” although it is not technically a fermentation as it does not involve the consumption of sugar and the production of alcohol. Instead, it is a conversion of malic acid to lactic acid by certain bacteria. Therefore, using the term “malolactic conversion” is more accurate than “malolactic fermentation.”


Overall, malolactic conversion is an important process in winemaking that can have a significant impact on the taste and texture of the wine. During the winemaking process of white wines, after the juice is extracted, it is often chilled to preserve freshness and prevent the growth of unwanted bacteria. But this step can also prevent the malolactic conversion from occurring naturally. Winemakers might then opt to inoculate the wine with a malolactic bacteria culture to ensure that the conversion takes place.


As our white wines are all naturally fermented, the conversion process could start naturally at the end of alcoholic fermentation, when the wine is nearing dryness. However, we will only allow a partial conversion in both our Chardonnay and Chenin Blanc as this allows us to retain a zestier and fresher acidity reflective of our cooler climate, in addition to a slightly creamier texture.


In the case of red wines, the malolactic conversion usually occurs during the aging process, as the wine is stored in oak barrels or stainless-steel tanks. Most red wines will undergo the conversion process naturally as the bacteria responsible for the conversion can be found naturally in the environment in which the aging takes place. At Oldenburg Vineyards all red wines undergo full malolactic conversion. The process is allowed to start naturally and is finished in the barrel roughly a month after pressing.


This stabilises the wine and prevents the wine from becoming fizzy and cloudy in the bottle. Additionally, if there is no malic acid remaining in the wine after the conversion process, the wine can be bottled unfined and unfiltered, as it is then microbially stable. Ultimately, this is a rather niche topic within the wine world. Take pleasure in the fact that you will now shine at your next wine general knowledge pop-quiz!

Back To Top