Malolactic fermentation: the secret to the balance of our red wines

While alcoholic fermentation is the most well-known stage of winemaking, malolactic fermentation (MLF) is an equally crucial step, particularly for crafting the fine red wines of Domaine du Père Auguste. Often called “the malo” by winemakers, it transforms the wine’s sensory profile.

What is malolactic fermentation?

Once the yeasts have finished their work of converting sugars into alcohol, a second biological transformation occurs. Unlike the first, it is not caused by yeasts, but by lactic acid bacteria (mainly Oenococcus oeni).

The principle is simple yet essential: these bacteria consume the malic acid naturally present in the grapes (a sharp acid, reminiscent of green apples) to transform it into lactic acid (a much softer acid, similar to that found in milk).

Why is this stage vital for our wines?

Malolactic fermentation is not just a simple chemical reaction; it brings three major benefits to the wine’s structure:

• Reduction of acidity: By replacing a strong acid with a weak one, the wine loses its biting sharpness and gains roundness.

• Biological stability: Once the bacteria have consumed the malic acid, the wine is “biologically stable.” This prevents unwanted fermentation from occurring later, once the wine is bottled.

• Softening and aromatic complexity: Beyond the texture, MLF develops more complex and rich aromas, with buttery, milky, or brioche notes that enhance the wine’s bouquet.

Temperature: the key factor for successful winemaking

The “malo” is a delicate process that requires constant monitoring in the cellar. Lactic acid bacteria are much more temperamental than yeasts.

The most critical parameter remains the cellar temperature. For the bacteria to activate, the wine must be kept within a precise range, generally between 18°C and 22°C.

• Too cold: Fermentation stagnates, leaving the wine vulnerable to spoilage.

• Too hot: There is a risk of developing undesirable bacteria that could harm the aromatic quality (lactic taint).

At Caves du Père Auguste, we pay special attention to this thermal control to ensure that each cuvée expresses the finesse of its terroir while maintaining a harmonious structure.

> Temperature, a key factor in winemaking