What causes buttery flavours in wine?

The key takeaways

• Diacetyl is the main compound linked with buttery wine.
• Malolactic fermentation, or MLF, is the most common winemaking pathway behind it.
• MLF does not automatically make a wine buttery.
• Oak can add vanilla, toast, spice, smoke or coconut-like flavours—but oak is not the same as butter.
• Lees contact can make wine seem creamier or rounder without directly causing buttery aroma.
• Chardonnay is a familiar example, but not all Chardonnay is buttery.
• Buttery character can be an intentional style choice or seem excessive, depending on intensity and balance.

How malolactic fermentation can create buttery character

Malolactic fermentation is a bacterial process that changes malic acid into softer-tasting lactic acid. Malic acid is the sharper acid also found in apples, while lactic acid is associated with a rounder impression.

During this process, lactic acid bacteria can also produce diacetyl. That compound is particularly associated with buttery and butterscotch-like aromas. The amount produced—and how much remains in the finished wine—depends on several winemaking conditions, including the bacterial strain, timing, temperature, oxygen conditions and the wine’s composition.

This is why it is more accurate to say that MLF can contribute to buttery flavour, rather than saying it always creates it. Some wines undergo MLF and show little or no obvious butter character. In other wines, the diacetyl is more apparent because it is produced in greater amounts or is retained rather than reduced during later winemaking.

Why not every wine that undergoes MLF tastes buttery

Diacetyl can be reduced during winemaking to compounds with less obvious flavour impact. Yeast and bacteria may help transform it, so the final wine can contain less noticeable butter character than it had earlier in its production.

Winemakers can also influence the result through choices such as:

• which malolactic bacteria are used;
• when MLF takes place;
• whether it occurs alongside or after alcoholic fermentation;
• how the wine is held after MLF;
• how the wine interacts with oxygen and lees.

These are influences, not simple switches. A wine’s acidity, fruit flavour and overall structure also affect how strongly you perceive butteriness.

Butter is not the same as oak

Oak and diacetyl are sometimes lumped together because they can appear in the same wine, particularly in some Chardonnay styles. They contribute different sensory impressions, however.

Oak is more directly associated with flavours and aromas such as:

• vanilla;
• toast;
• baking spice;
• smoke; and
• coconut-like character.

Diacetyl is more closely associated with butter, butterscotch and buttered popcorn.

A wine can show both. For example, a Chardonnay may have undergone MLF and matured with oak, producing a combination of buttery, vanilla and toasted impressions. That does not mean the oak caused the butter flavour.

Where lees and creaminess fit in

Lees are the sediment left behind after fermentation, made up largely of yeast cells and other solids. Keeping wine in contact with lees—and sometimes stirring them, a practice called bâtonnage—can influence texture, roundness, fullness and integration.

That may make a wine feel creamy or smooth. But “creamy” is a broad word: it can describe an aroma, a soft texture, a fuller body, reduced acidity or several of these sensations at once.

Creaminess and butteriness can overlap, but they are not identical. A wine may feel creamy without smelling of butter, or smell buttery without having a particularly rich or creamy texture. Lees can also influence how diacetyl is managed, but they are not the primary explanation for buttery aroma.

Why Chardonnay is often part of the conversation

Chardonnay is a useful example because winemakers can make it in many different ways. In Australia, Chardonnay may be made with no MLF, partial MLF or full MLF, and with varying levels of oak and lees contact.

That helps explain why one Australian Chardonnay may taste fresh, citrus-driven and tightly textured, while another seems rounder, creamier or more buttery. These are production choices and style differences—not characteristics that apply to every Chardonnay.

Butteriness is also not exclusive to Chardonnay. Diacetyl can influence other wines when the relevant fermentation and cellar conditions allow it to develop and remain noticeable.

Is a buttery wine faulty?

Not necessarily.

A modest buttery note may be an intentional part of a wine’s style, adding richness or complexity alongside fruit and acidity. The same character can seem excessive in a wine intended to be fresh, delicate or strongly fruit-driven.

The useful question is not simply “Is butter good or bad?” Instead, ask:

• How strong is the buttery character?
• Does it sit comfortably with the fruit and acidity?
• Does it suit the wine’s intended style?
• Do you enjoy the balance?

A strongly buttery aroma may be regarded as undesirable in some circumstances, but one tasting descriptor alone is not enough to diagnose a fault.

How to taste for buttery character

When you open a wine, try separating the impressions rather than treating every rich note as “butter”.

1. Smell the wine before tasting. Look for butter, butterscotch, cream or buttered popcorn.
2. Look separately for oak notes. Vanilla, toast, smoke, spice and coconut-like aromas point towards a different influence.
3. Notice what “creamy” means. Is it an aroma, a soft texture, a fuller mouthfeel or simply lower-feeling acidity?
4. Smell again after a few minutes. The balance of aromas can change as the wine warms slightly and has time in the glass.
5. Consider the whole wine. Fruit, acidity, texture and intensity matter more than the presence of one descriptor.

This will not prove the exact chemical cause of a flavour. It is a way to become more precise and confident when describing what you notice.

For more on the foundations of wine aroma, see [What is wine aroma?]. For practical tasting technique, read [How to taste wine]. Chardonnay is explored in [What is Chardonnay?].

Frequently asked questions

Does malolactic fermentation always make wine buttery?

No. MLF can produce buttery-associated diacetyl, but the amount produced and retained varies with bacterial strain, timing, temperature, oxygen conditions, wine composition and later biological activity.

Does oak make wine taste like butter?

Oak can accompany buttery character, but it is not the main explanation for it. Oak more directly contributes vanilla, toast, spice, smoke and coconut-like notes.

Can a wine be creamy without being buttery?

Yes. Creaminess may describe texture, body, softness or integration rather than a butter-like aroma.

Is all Chardonnay buttery?

No. Chardonnay can be fresh and citrus-driven, rich and creamy, lightly oaked, strongly oaked or made in many styles between these descriptions.

Is buttery wine a fault?

Not automatically. Its appropriateness depends on intensity, balance, style and personal preference.