Malolactic Fermentation in Winemaking: What Is It All About?

Wine has to proceed through many steps before it reaches its ideal condition and flavour. The grapes not only need to be smashed to produce the needed must for the rest of the steps, but the wine has to undergo chemical reactions to form its characteristics in an effective fashion. Malolactic fermentation is just one of the reactions. We explain this winemaking stage in further detail in the following to enable you to better understand it and when to use it.

What Is Malolactic Fermentation?

Malolactic fermentation or MLF is when the tart-tasting malic acid that is present naturally in grape must converts to the milder-tasting lactic acid in many of the wines that winemakers produce. This process usually is performed after the primary fermentation process finishes but can happen simultaneously when desirable. All red wines and certain white wines benefit from undergoing MLF. Unlike primary fermentation that is for converting sugar into alcohol by yeast, MLF happens because of the bacteria called Oenococcusoeni. Even though this process can occur naturally, many winemakers help it along by interjecting their wines with a bacteria culture to start the MLF.

What Is Malic Acid?

Malic acid is found in many fruits, including grapes. This acid produces a strong flavor similar to that of green apples, and it needs mellowing out in order to receive the ideal results in your wine.

What Is Lactic Acid?

Lactic acid is commonly found in dairy products and has a rich, buttery flavour. Once the wine goes through MLF, the malic acid is transformed into lactic acid. Therefore, lactic acid balances the malic acid and prevents undesirable flavours from occurring in the wine.

The Ways That Malolactic Fermentation Affects Wine

  • MLF produces a fuller, rounder mouthfeel to the wine since it balances out the taste of the malic acid with lactic acid.
  • Also, MLF typically improves the flavour and body of wine by creating an end result that is soft on the palate. For example, red wines tend to b a bit astringent and harsh on the palate prior to malolactic fermentation. After it though, they are softer to the mouth.
  • By a wine going through MLF on a planned basis, you ensure that it will not occur after you bottle the wine. When MLF happens naturally at this stage, it can produce unwanted side effects that range from carbonation in a non-sparkling wine to strange flavours.