Cold Soak Winemaking: What It Does and Why It Matters

Cold soak winemaking keeps crushed red grapes cold for a few days before any yeast gets to work. In that pause, chilled juice draws colour out of the grape skins the way cold water draws flavour from coffee grounds. The method aims to give a pale grape like Pinot Noir a deeper colour, but the research on whether it works is mixed.

What Is a Cold Soak in Winemaking, in One Paragraph?

A cold soak, also called cold maceration or pre-fermentation maceration, holds crushed red grapes at low temperature for a few days before fermentation. Maceration means leaving the juice in contact with skins, seeds and pulp. The crushed mix is called must. During the soak the must sits at about 5 to 15 °C, often colder, for three to five days. Sulfur dioxide is added, and sometimes dry ice. Extraction relies on water and that sulfur dioxide instead of heat and alcohol. Then the tank warms up and fermentation starts. Burgundy made the technique popular in the 1970s and 1980s, and oenologists still debate how much it improves the wine.

How Does a Cold Soak Work?

Cold juice is a water-based solvent, so it pulls out compounds that dissolve well in water before any alcohol exists. The 2026 review by Sternad Lemut and colleagues describes this as extraction in "an aqueous, ethanol-free medium". That favours what sits in the skins over what sits in the seeds.

Cold-brew coffee is a useful analogy, though only an analogy. It steeps for hours in cold water and comes out less bitter than coffee made with hot water. A cold soak works on the same idea: low temperature and no alcohol mean a slower, more selective pull.

The skins hold the anthocyanins, the pigments that make red wine red. They diffuse quickly into the cold juice. The seeds hold harsher tannin (the drying grip on your gums). The same review notes that seed compounds usually need ten days or more of maceration to come out in quantity, so a short cold soak is expected to take little from them, though some studies found the opposite.

Once the soak ends, the winemaker lets the tank warm. Yeast wakes up, sugar turns to alcohol, and alcohol takes over as the main solvent. Our guide to how yeast drives fermentation covers that next stage.

What Does a Cold Soak Change in the Wine?

Mostly early colour, sometimes seed tannin, and little else that is proven. Winemakers credit the soak with deeper colour, softer tannin, more aroma and better wine overall. The evidence is strongest for the first, thin for the second, and unsettled for the last two.

Claimed effect	What the research shows	What to look for in your glass
Deeper colour	Anthocyanins diffuse fast in cold juice and can lift early colour intensity; some studies find no lasting gain	Tilt the glass over white paper: a young red with a purple rim and dark core
Softer tannin	Lower seed tannin was confirmed in Teran wines, but other studies found more seed tannin	Less drying grip on your gums after you swallow
More aroma	The review says the soak may reshape the aroma profile; no single effect is settled	Nothing reliable: aroma depends on too many other steps
Better wine overall	Effects vary across grapes and vintages; oenologists still debate it	Judge the wine, not the method on the back label

The tannin result comes from Teran, a red grape of the Slovenian and Croatian coast. There, the lower extraction of seed tannins was still visible in the finished wines. That is one grape, and other studies found more seed tannin, not less. Our explainer on what tannins are shows why seed tannin feels harsher than skin tannin.

How Cold and How Long Is a Cold Soak?

Usually 5 to 15 °C, often as low as 3 to 5 °C, for three to five days. The 2026 review by Sternad Lemut and colleagues also reports soaks stretched to 10 or even 12 days. A longer soak gives the skins more time, and every extra day keeps a tank full of unprotected juice waiting.

One real cellar trial landed in the middle. In a study of California Syrah by Stoffel and colleagues, every batch had a five-day cold soak averaging 10.6 °C. That is cold enough to keep yeast quiet without the near-freezing temperatures some cellars use.

Why Do Winemakers Add Sulfur Dioxide or Dry Ice?

Both protect juice that is sitting still for days with no alcohol to guard it. Cold alone slows the enzymes that brown and oxidise juice, and it delays unwanted microbes. Sulfur dioxide strengthens both effects, and dry ice adds a fast chill plus a shield against oxygen.

Sulfur dioxide (SO2, the same preservative behind the "contains sulfites" line on labels) holds back wild yeast and acetic acid bacteria, the microbes that turn wine toward vinegar. Our guide to sulfites in wine explains where else it is used.

Dry ice is solid carbon dioxide. Dropped onto crushed grapes, it cools them fast. As it turns to gas, it lays a blanket of carbon dioxide over the must that keeps oxygen away. The review singles it out as particularly effective because it does both jobs at once.

Does Cold Soaking Really Work?

Sometimes. The 2026 review states that reported effects on anthocyanins, total phenolics and colour "are not always consistent", and that some studies show negative or negligible outcomes. The grape and the vintage decide much of it, and even pale Pinot Noir, which looks like it has the most to gain, often responds poorly.

That debate is old. Cold soaks became popular in Burgundy in the 1970s and 1980s, and oenologists still disagree about how much they improve wine quality. Burgundy's reds are Pinot Noir, which the same review describes as challenged in colour intensity and stability because of its naturally low anthocyanin content, yet notes it often responds poorly to a cold soak.

So judge it grape by grape. For pale, thin-skinned Pinot Noir, a cold soak is a hopeful bet for colour, not a sure one. For dark, thick-skinned grapes that already give plenty of pigment, it is a style choice with little to fix. Our guide to thick- and thin-skinned grapes shows which grapes fall where.

Cold Soak Winemaking vs Extended Maceration vs Cold Fermentation

The three names sound alike but sit at different points in winemaking. A cold soak happens before fermentation, in juice with no alcohol. Extended maceration happens after it, in finished wine left on its skins. Cold fermentation is fermentation itself kept cool, a method used mostly for whites.

Technique	When	Temperature	Main goal
Cold soak	Before fermentation, no alcohol yet	Cold, about 5 to 15 °C	Pull colour from skins with water
Extended maceration	After fermentation, wine left on skins	Cellar temperature	More tannin and texture over days or weeks
Cold fermentation	During fermentation	Cool, mostly for white wines	Keep fresh fruit aromas

Cold soak is not cold fermentation: during the soak, no fermentation happens at all. The two steps can also pull in opposite directions. In the Syrah study, wines given extended maceration ended with lower colour saturation, likely because pigments degraded or stuck to solids. The same study found that cap management (how the floating layer of skins is pushed back into the juice) and maceration length shaped the taste more than alcohol level did. For a fourth method that ferments whole grapes, see carbonic maceration.

Which Wines Use a Cold Soak?

It began with Burgundy Pinot Noir, but the 2026 review says it is now used broadly across grapes and regions. Studies cover Cabernet Sauvignon, Merlot, Syrah, Tempranillo and Teran, among others. Wineries rarely print it on the front label. When they mention it at all, it appears on back labels and on winery technical sheets, the one-page notes that list harvest and cellar details.

If a back label or tech sheet mentions a cold soak on a Pinot Noir, expect a winemaker chasing deeper colour and fresh fruit. If it appears on a dark grape such as Syrah, read it as a style choice. If the sheet says nothing, assume nothing: plenty of good Pinot is made without one. Our Pinot Noir guide and Burgundy wine guide show the range of styles this grape gives with or without it. More production choices that shape style sit in the wine styles hub.

Can You Taste a Cold Soak in the Glass?

Not reliably. Its best-supported effect, early colour, is also shaped by grape, ripeness, vintage and age, so no taster can name the method blind. What you can read is the colour it aims for: a deep core and a violet rim in a young red.

If one young Pinot Noir looks deep purple and another pale ruby, check the vintage first. Colour fades toward garnet as wine ages, as our guide to wine colour and age explains. Only when two wines are the same age and grape does a colour gap start to point at winemaking. Our guide to what wine colour means covers how to read hue, depth and rim.

The Sommy app teaches this kind of reading in bite-sized courses, including Wine 101. Tonight: pour any red, tilt it over white paper, and note whether the rim is violet, ruby or brick before you take the first sip.

Sources

1. Sternad Lemut et al., Traditional and Emerging Maceration Techniques in Red Winemaking, Foods (2026)
2. Stoffel et al., Molecules (2025): cold soak, cap management and maceration length in California Syrah
3. Wikipedia: Maceration (wine)