Discovery / Methodology / Malolactic Fermentation
Meet the method · Follow your curiosity
Malolactic Fermentation
Malolactic fermentation changes a wine’s acid profile and can influence flavour and texture—a separate transformation from yeast making alcohol.
A little acquaintance, at a glance.
- Starting point
- Lactic acid bacteria
- Main change or choice
- Malic acid becomes lactic acid
- In the wine world
- Most reds; selected whites & sparkling bases
- Useful question
- A choice about style & stability
A choice that shapes the wine.
Chardonnay is a familiar starting point, while most red wines also undergo this conversion. The Australian Wine Research Institute describes MLF as a bacterial process used in most reds and some white and sparkling wines. It can matter to both stability and style. Our Elena Walch estate entry and the producer’s Beyond the Clouds information provide a useful white-wine connection.
How the method works.
A different transformation
Lactic acid bacteria convert malic acid to lactic acid and carbon dioxide. This is distinct from alcoholic fermentation, in which yeast converts sugar to alcohol. A rounder impression should therefore not be mistaken for extra residual sugar.
Timing is a choice
MLF often follows alcoholic fermentation, but producers can also manage it alongside that fermentation. Whether it is encouraged, limited or avoided depends on the wine and the intended style. Cellar monitoring establishes what actually happened.
The finished style
Changes can include reduced acidity and altered aroma or mouthfeel. A producer may allow only part of a white wine through MLF and blend portions later. Read the stated approach rather than expecting every wine of a variety to follow one recipe.
What to notice in your glass.
Acidity
Consider how the wine feels fresh or rounded, keeping sweetness as a separate observation. MLF is one possible influence among several.
Butter & other aromas
Diacetyl can contribute a buttery aroma. Its level and perception depend on production choices and the wine, so MLF does not require every wine to taste strongly buttery.
Oak & lees
Oak maturation, yeast lees work and MLF can occur in related cellar programmes, but they describe different things. A creamy impression alone does not identify which decisions were made.
Keep the connections clear.
“Malo” is shorthand you may hear in a tasting room. A useful follow-up is whether the producer means full, partial or no malolactic conversion, and how that relates to the particular wine. Alcoholic fermentation, MLF, oak maturation and lees contact are four separate entries in your notebook. Several may contribute to one finished wine.
Try a little discovery.
Find two Chardonnay technical descriptions that explicitly state different MLF choices. Record oak, lees, vintage and origin too. If tasting, use equal small pours at similar temperatures and describe acidity, aroma and texture separately. A tasting can explore the result; it cannot isolate MLF if all the other conditions also differ.
Small pours, your own words, and no marks for impressive vocabulary.
A few questions worth uncorking.
Does malolactic fermentation make wine sweet?
Its principal conversion concerns acid, not grape sugar. A softer impression is not the same as sweetness.
Must a wine that underwent MLF taste buttery?
No. Diacetyl levels and perception vary, and producers can manage the aromatic outcome.
Where shall we wander next?
Wine Fermentation →Chardonnay →Elena Walch Winery →Aging on the Lees →Oak and Stainless Steel →Making Bubbles →Behind this introduction
Editorial sources checked 16 October 2026. The process cards are explanatory diagrams; tasting observations need the context of a particular wine.