Malolactic Magic : the Science behind the softness of Beaujolais

What is malolactic fermentation?

Malolactic fermentation (MLF) — often shortened to “malo” by winemakers — is not a fermentation in the traditional alcoholic sense. Instead, it’s a biological conversion where one type of acid is transformed into another.

Specifically, malic acid (the same tart acid found in green apples) is converted into lactic acid (the gentler acid found in yogurt and milk). This process is carried out by specific lactic acid bacteria, notably Oenococcus oeni, along with Lactobacillus and Pediococcus species.

MLF is widespread in red winemaking, especially in cooler-climate regions where malic acid levels are high. And it’s absolutely central to the vinification of Beaujolais wines, where the Gamay grape naturally carries a lot of this sharp malic acid.

From Malic to Lactic: a molecular makeover

Let’s simplify the chemistry.

• Malic acid has two carboxyl groups (–COOH), making it sharper and more acidic on the palate.
• Lactic acid has only one carboxyl group, giving it a softer, creamier sensation.

During MLF, the bacteria metabolize malic acid into lactic acid and carbon dioxide. The wine becomes less acidic, more stable, and silkier. For Beaujolais wines, this means taming Gamay’s brightness and transforming it into that signature supple texture.

Why Beaujolais wines rely on malolactic fermentation

Gamay noir à jus blanc — the grape at the heart of Beaujolais — is thin-skinned, low in tannins, but naturally high in malic acid. Without MLF, the wines could feel overly sharp or “green”.

That’s why almost all Beaujolais reds undergo full malolactic fermentation, especially those from the ten crus like Morgon, Fleurie, or Chiroubles, where a more structured and cellar-worthy profile is sought.

Even Beaujolais Nouveau, known for its lightness and early release, goes through MLF — but it’s done quickly and often concurrently with or immediately after alcoholic fermentation to retain maximum fruit.

Malolactic fermentation and carbonic maceration: a Beaujolais Signature

Here’s where it gets even more interesting.

Beaujolais is globally known for its use of carbonic maceration, especially in Nouveau and some village wines. This technique involves fermenting whole grape clusters in a CO₂-rich environment, promoting intracellular fermentation that enhances fruity esters and minimizes tannin extraction.

But carbonic maceration doesn’t generate enough heat or oxygen to trigger MLF naturally. That’s why once the wine is pressed and alcoholic fermentation finishes, winemakers must closely manage conditions to encourage malolactic bacteria — either by gently warming the wine, inoculating with cultures, or simply waiting.

This dual fermentation strategy — carbonic maceration + malolactic fermentation — is what gives Beaujolais its unique profile: aromatic brightness paired with plush texture.

Natural vs Controlled MLF in Beaujolais

The Beaujolais region is a mosaic of winemaking philosophies.
Some producers embrace natural wine methods, using ambient yeasts and spontaneous MLF, while others prefer more controlled techniques, especially in commercial-scale wineries.

In natural MLF, winemakers do not inoculate but allow native lactic acid bacteria to take over once conditions are right. This can result in slower but more expressive fermentations, often seen in cult domains like Yvon Métras, Jean Foillard, or Julie Balagny.

Controlled MLF, by contrast, involves:

• Adding selected bacterial strains
• Monitoring temperature (optimal: 18–22°C)
• Managing SO₂ levels to avoid inhibition

This ensures a clean, predictable fermentation — crucial in large-volume or export-sensitive production.

Beaujolais Blanc and malolactic fermentation: a separate story

Though red wines dominate the region, Beaujolais Blanc — made from Chardonnay — is gaining traction.

Here, the use of MLF is a stylistic choice:

• Some winemakers block MLF to retain citrus-driven acidity and a more Chablis-like freshness.
• Others let it proceed to create a richer, creamier texture, closer to Mâconnais or Côte de Beaune styles.

As the climate warms and acid retention becomes harder, MLF decisions in Beaujolais Blanc may evolve — a point worth watching in future vintages.

Does MLF influence ageability?

Absolutely. One of the lesser-known advantages of MLF is its impact on wine stability.

By converting malic acid (a possible food source for spoilage organisms), MLF:

• reduces the risk of refermentation in bottle
• enhances microbial stability
• contributes to smooth integration of oak if used

In cru Beaujolais, where some wines age 5–10 years or more, this is essential. Wines like Côte de Brouilly or Moulin-à-Vent, known for their structure, benefit greatly from a well-conducted MLF.

However, excessive or poorly managed MLF — especially in warm vintages — can flatten acidity and make the wine taste dull or “flabby.” As always, balance is key.