Cold Soak / Cold Maceration (Pre-Fermentation Skin Contact for Color & Aroma)

Cold soak, also known as cold maceration or pre-ferment maceration, is a winemaking step in which crushed red grapes are held at a low temperature for a period of time before fermentation starts. It is a common technique that is widely used in the production of red wines. The principle is that while grape skins are in contact with juice before any alcohol is formed, anthocyanin extraction is enhanced, as is the extraction of aroma and flavour compounds, which is associated with improved overall wine quality. Extraction also occurs during fermentation, but many winemakers feel cold soaking brings out different, and beneficial, aspects of the grapes.

• The grapes must be kept chilled to stall fermentation, and the length of time varies with the winemaker's goals and the grape variety
• Maceration time runs anywhere from as little as 5 to 10 hours to as much as 10 days
• Cold soak is not limited to reds: the advice to keep the must truly cold covers cold soak with white or red grapes, and some orange wines are cold soaked before fermentation too

Vine Cliff winemaker Rex Smith sees the main advantage of cold soaking as extracting color and flavor in an aqueous environment, without extracting tannin, because the solvent effect of alcohol is absent. He adds that nutrients in the grape skins go into solution and become available for the yeast to use. More broadly, pre-fermentation maceration helps leach tannins, anthocyanins and flavour compounds from the crushed grapes into the juice.

• Some winemakers add enzymes to help the extraction along, sulfur dioxide to inhibit unwanted microbial activity, and inert gas to prevent oxidation
• Rex Smith extracts color and flavor first, then dials in the tannins during fermentation, draining and pressing when the tannin balance is right
• At the beginning of the winemaking process, maceration often refers to cold-soaking unfermented grape juice in the crushed skins, seeds and stalks of the grape

Cold soak is associated with improved overall wine quality through greater extraction of anthocyanins and of aroma and flavour compounds, but results vary by variety and climate. Work by Fennessy found that cold-soaking different red varieties (Cabernet Sauvignon, Shiraz and Merlot) can achieve different results, and that climate plays a role: cold-soaked warm-climate fruit showed larger colour differences than cold-soaked cool-climate fruit, with the greatest colour differences in Cabernet Sauvignon. For Pinot Noir in Burgundy, the idea is that more color transfers to the juice for a deeper, richer wine than if the thin-skinned grape was simply fermented, though WSET instructor May Matta-Aliah points out that not all winemakers agree that such a transfer happens to any significant degree.

• For Rex Smith, working without the solvent effect of alcohol means cold soaking avoids extracting harsh tannins, bitterness or astringency
• A thick-skinned grape such as Cabernet Sauvignon infuses more color, faster, than a thin-skinned one such as Pinot Noir, and a dark color does not necessarily mean a better wine

Winemakers cold-soak all kinds of reds, and some grapes and wine styles are more extractable than others. For Rex Smith, the cold soak period also allows indigenous yeast to grow and start the fermentation without the warmth that encourages spoilage organisms to thrive. Fruit condition matters: cold soak is very risky with damaged fruit, since studies at Cornell University showed that damage by powdery mildew (and following Botrytis) brings grapes with a much higher load of yeast and bacteria than healthy undamaged fruit.

• Damaged fruit can carry more than several million yeast per milliliter of juice, mostly Kloeckera, Pichia and Candida species that can produce large amounts of acetic acid and acetic acid esters
• In cool climates where fruit arrives cold, practitioners of cold soak (holding juice at 41 to 50°F) may save some money, but the must still has to be heated up for fermentation

In Burgundy, some Pinot Noir producers still cold soak, keeping the grapes and juice at a temperature low enough that fermentation does not begin for a couple of days. Clive Coates MW lists cold soaking before fermentation or not among the choices that vary from one Burgundian winemaker to the next, observing that lots of people cold macerate, but not Rousseau. In Oregon, Stoller Family Estate puts its Pinot Noir through a sorting line and a destemmer directly above the fermentation tanks, where the whole berries remain at cool temperatures for up to 10 days before a fermentation that usually takes five to seven days.

• Stoller Family Estate calls its cold soak a style choice that facilitates color and flavor extraction before the production of alcohol
• Vine Cliff winemaker Rex Smith cold-soaks Merlot

Winemakers initiate cold soak by crushing red grapes, pumping the must to a tank or storage vessel, and holding it at 5 to 10°C, the typical range for cold soaking temperatures. Covering the fruit during cold soaking is recommended to minimize the risk of spoilage organisms, and using CO2 is advisable to reduce the chance of oxidation. Sulfur dioxide should be added at crushing, and SO2 at 30 to 50 PPM, depending on pH, is advised to help suppress unwanted yeast and bacteria during the soak. At the end of the cold soak period, the must should be warmed quickly to 65 to 68°F to favor the growth of Saccharomyces and start the fermentation.

• Options for cooling must include harvesting at the coldest point of the day, chilling hand-picked fruit in cool rooms before crushing, using dry ice in the must, and using tanks with cooling jackets or internal cooling plates
• Dry ice coverage should also be maintained during the cold soak period to minimise oxidation and avoid aeration, and the storage vessel should be covered to keep out unwanted microflora
• In a 2018 Cabernet trial, crushed fruit with acid and SO2 additions was held at approximately 3°C in a 0°C cool room for five days, then moved to 20°C and inoculated once the must reached 15°C, which took 24 hours
• A yeast starter culture, adapted slowly to the low temperature of the must, can be added immediately after crushing to help suppress unwanted yeast and bacteria

Primary sources (the Australian Wine Research Institute, Washington State University Viticulture and Enology extension, and Stoller Family Estate for its own winemaking): https://www.awri.com.au/industry_support/winemaking_resources/winemaking-practices/winemaking-treatment-cold-soak/, https://wine.wsu.edu/note-to-cold-soak/, https://wine.wsu.edu/late-ripening-how-to-deal/, https://www.stollerfamilyestate.com/about/our-winery-new/. Secondary: https://www.winespectator.com/articles/what-does-cold-soaking-do-for-grapes-5337, https://www.decanter.com/learn/wset/letting-the-wine-stew-maceration-factors-that-influence-wine-wset-level-2-282923/, https://www.decanter.com/learn/what-does-maceration-mean-ask-decanter-442910/, https://www.decanter.com/features/burgundian-wine-scene-winds-of-change-247684/. Last verified 2026-10-04