Malolactic Fermentation

Wine appreciation and wine production are filled a variety of terms and terminology. Some are easy to understand while others can be more complex. While fermentation of wine is largely something that is largely understood, yeast converting sugar into alcohol and CO2, Malolactic fermentation, aka “ML”, is often polarizing and misunderstood. Malolactic fermentation is a secondary fermentation process in winemaking that converts malic acid into lactic acid. This process is typically carried out by specific bacteria after the primary fermentation.

Here's how it works:

• Malic Acid: is an organic acid found in wine, giving it a tart, green apple-like taste. It’s more prevalent in cooler climate white wines such Riesling, Sauvignon Blanc, and Pinot Gris.

• Lactic Acid: is a softer, rounder acid found in dairy products, contributing to a smoother, and creamier texture.

• Bacterial Conversion: During malolactic fermentation, bacteria consume the malic acid in the wine and convert it into lactic acid and carbon dioxide (CO2). This transformation reduces the wine's acidity, making it less tart and often more approachable.

Benefits of Malolactic Fermentation:

• Mouthfeel: It softens the acidity of the wine, leading to a rounder mouthfeel and a smoother flavor profile.

• Stability: malolactic fermentation can help stabilize the wine by reducing the levels of malic acid, which can be prone to spoilage under certain conditions.

• Flavor Complexity: In some wines, malolactic fermentation can also introduce subtle flavors such as buttery or creamy notes, particularly in wines like Chardonnay. This is often associated with the "buttery" characteristic in wine.

Misconception of Malolactic Fermentation

While malolactic fermentation’s effect of giving wine, specifically white wines, a richer, rounder mouthfeel is clear, it can sometimes give wines a flabby style lacking acidity. This example is most common in some Chardonnays, rendering them unbalanced and unctious. This often happens when the malolactic fermentation takes place during primary fermentation. This doesn’t always have to be the case.

When ML takes place after primary fermentation, wines have a brighter, more balanced style with a good vein of acidity and rich mouthfeel.

Ultimately, the use of ML softens the wine, reduces sharp acidity, and can contribute to a more complex flavor profile, making it an important technique in many winemaking styles.

Does Every Wine Go Through Malolactic Fermentation?

Not all wines undergo malolactic fermentation. While red wines and fuller-bodied white wines like Chardonnay are more likely to undergo malo, many lighter white wines (such as Sauvignon Blanc or Riesling) are intentionally kept from going through this process to preserve their crisp acidity and fresh fruit flavors.

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