What Is Cold Soak in Winemaking?

Quick answer

Cold soak is a pre-fermentation period when crushed red grapes or grape must are kept cool while the juice remains in contact with the skins and seeds. The cool conditions are intended to delay or limit alcoholic fermentation while extraction begins.

Winemakers may use cold soak to influence the wine’s colour, aroma, flavour and tannin structure. Before alcohol is produced, the extraction environment is different from the one created during fermentation. This can change which compounds move from the skins and seeds into the juice.

The effect is not automatic. Cold soak may contribute to deeper colour or more noticeable fruit character in some wines, while producing little measurable difference in others. Tannin, bitterness and astringency may also change, depending on the grape variety, ripeness, temperature, length of the soak, fruit condition and the fermentation and maceration that follow.

So, in plain English: cold soak gives a winemaker another opportunity to shape a red wine before fermentation gets underway.

How cold soak fits into winemaking

After red grapes are crushed, the resulting mixture of juice, skins and seeds is called must. During a cold soak, the must is held at a low temperature before substantial alcoholic fermentation begins.

The juice remains with the skins and seeds for a period of time. Once fermentation starts, yeast converts grape sugar into alcohol and carbon dioxide. That alcohol changes the conditions in which compounds are extracted from the grape solids.

Cold soak therefore occupies a specific place in the process:

1. Grapes are crushed.
2. Juice, skins and seeds remain together.
3. The must is kept cool before substantial fermentation.
4. Alcoholic fermentation begins.
5. Skin contact and extraction continue according to the winemaker’s broader choices.
6. The wine is eventually pressed and matured.

Cold soak is sometimes called pre-fermentation cold maceration or pre-ferment maceration. “Maceration” is the broader term for keeping juice in contact with grape solids. Cold soak is one particular type of maceration, defined by its timing and cool conditions.

Why do winemakers use it?

The main aim is to influence extraction before alcohol is present. Winemakers may be seeking changes in:

Colour

Red wine colour comes largely from compounds in grape skins. Cold soak may help extract colour in some circumstances, but research does not show a universal result. Vintage, grape maturity, variety, temperature and later maceration can all change the outcome.

A cold-soaked wine is not automatically darker or more colour-stable than one made without the technique.

Aroma and flavour

Skin contact before fermentation may influence the compounds that contribute to aroma and flavour. Some winemakers use cold soak with the intention of encouraging fruit expression or adding another layer of character.

However, the finished aroma is also shaped by yeast, fermentation temperature, cap management, maturation and blending. If a wine smells fruitier, cold soak may be one contributing factor—but it is rarely the only explanation.

Texture and tannin

Tannins contribute grip, dryness and astringency. Cold soak changes the timing and conditions of extraction, so it may affect the balance between colour, tannin and texture.

This is where simple explanations become unreliable. Cold soak is sometimes described as extracting colour while limiting tannin, but studies have also found different tannin results depending on the fruit and treatment. It is more accurate to say that cold soak may alter the wine’s textural balance rather than promising softer tannins.

What affects the result?

Cold soak is not a single fixed recipe. Its effect can vary with:

• grape variety, including Shiraz, Cabernet Sauvignon, Merlot or Pinot Noir;
• grape ripeness and seed maturity;
• fruit condition;
• temperature;
• length of time;
• yeast activity;
• sulphur dioxide use;
• how the must is handled;
• the temperature and length of the fermentation that follows; and
• later maturation and blending.

These variables matter in Australian winemaking too. Australian readers may encounter “cold soak” in discussions of Shiraz, Cabernet Sauvignon, Pinot Noir and other red wines, but the technique is not uniquely Australian and is not used by every producer. Research involving Australian-relevant varieties has found that results can differ with variety and climate.

What might you notice in the finished wine?

If cold soak has influenced a wine, you might notice a difference in colour, fruit expression, body or texture. Some wines may seem more aromatic or fruit-driven; others may show a different level of grip, bitterness or astringency.

But you cannot reliably identify cold soak from one bottle. The wine’s character reflects the combined effect of the grapes, vintage, fermentation, extraction, maturation and blending. A tasting note that mentions ripe fruit or smooth tannins does not prove that cold soak was used.

Cold soak compared with similar terms

Cold soak and cold fermentation

These are not the same. Cold soak happens before alcoholic fermentation. Cold fermentation means the alcoholic fermentation itself is carried out at a relatively low temperature.

Cold soak and cold stabilisation

Cold stabilisation is a later treatment applied to wine, usually by chilling it so tartrate crystals can form and be removed or reduced before bottling. It is not a grape-skin extraction technique.

Cold soak and extended maceration

Extended maceration usually means keeping wine in contact with skins and seeds for an extended period, often after fermentation. Cold soak happens before substantial fermentation, so the timing and extraction conditions differ.

Cold soak and carbonic maceration

Carbonic maceration is a different technique involving whole or mostly intact grapes in a carbon-dioxide-rich environment. It encourages intracellular fermentation. It is not simply a colder version of ordinary maceration.

Frequently asked questions

Does cold soak make the wine colder?

Only during that stage of production. “Cold soak” describes a cool pre-fermentation process, not the serving temperature of the finished wine.

Does cold soak always increase tannin?

No. Tannin results vary with the grapes and the winemaking that follows. Cold soak may change the balance of tannin, bitterness and astringency, but it does not guarantee a particular texture.

Does every red wine use cold soak?

No. It is a common option in red-wine production, but winemakers choose techniques according to the fruit, wine style, winery facilities and desired result.

Is cold-soaked wine better?

Not automatically. Cold soak is a tool, and its success depends on how it suits the fruit and the rest of the winemaking process.

Cold soak is best understood as one decision within a much larger chain of decisions. To place it in context, read How wine is made. You can also explore How to taste wine to think about how colour, aroma and texture appear in the glass.