Cryoextraction for Late Harvest Concentration

Cryoextraction involves freezing harvested grapes artificially, rather than letting them freeze on the vine as ice wine grapes do. The OIV's International Code of Oenological Practices gives cryoextraction its own sheet (II.1.10.4) under the control of the sugar content of harvested grapes, whose objective is to increase the sugar content of the raw materials used. The same section lists cryoselection by physical procedures, partially freezing grapes in a cold room, then pressing at a low temperature in order to produce a must with a higher sugar content, and sets it beside cryoselection in the vineyard without recourse to physical procedures, where grapes partially freeze on the vine before pressing, the route the OIV requires for icewine. Sarah Jane Evans MW, writing in Decanter, names three ways to concentrate sugar in traditionally made sweet wines: botrytis or noble rot, freezing, and drying the grapes on the vine or after picking.

• Wine Spectator's Dr. Vinny (2007) describes "non-natural" ice wines, in which a producer picks the grapes and then freezes them mechanically, and notes that these are sometimes called "icebox wines" or "iced wine"
• Decanter reports that Sauternes producers such as Château d'Yquem make use of cryoextraction
• The OIV's cryoextraction sheet (II.1.10.4) is flagged as one whose production conditions are being studied; the parent sheet on controlling the sugar content of harvested grapes (II.1.10), which lists both cryoselection routes, carries the recommendation Admitted

Harvested grapes are chilled mechanically: Wine Spectator's Dr. Vinny describes producers who pick the grapes and then freeze them mechanically, and the OIV's Code describes partially freezing grapes in a cold room. Frozen grapes are then handled while still cold: the OIV's description of cryoselection by physical procedures calls for pressing at a low temperature. The principle is the one ice wine relies on: Wine Spectator explains that only the water in the grape freezes, while sugars and other components do not. When pressed, frozen grapes leave their water behind as ice; for Eiswein, Wines of Germany explains that the water contained in the berries remains as ice on the wine press, while only the sweetest juice, whose freezing point is lower than that of water, is obtained as a highly concentrated must. The concentrated must then ferments slowly: Wines of Germany notes that yeasts have great difficulty fermenting must with such a high sugar content.

• For natural ice wine, Wine Spectator's Dr. Vinny notes that the grapes must be both picked and pressed while still frozen, and that the very high sugar levels make for slow fermentations
• Wines of Germany reports that German ice wines generally have a residual sugar content of well over 100 grams per liter and a relatively low alcohol content, often only around 7% by volume

Sarah Jane Evans MW, in Decanter, weighed cryoextraction as a fallback for ice wine and was frank about the trade-off: "The romance may be lost, the complexity of flavour may disappear, but wine from frozen grapes will remain viable." For ice wine itself, she writes that freezing the grapes concentrates the acidity as well as the extract, so the wines can taste fresh as well as very sweet.

• Wine Spectator's Dr. Vinny notes that ice wine grapes tend not to be affected by Botrytis cinerea, which gives ice wines a refreshing acidity
• Wines of Germany attributes Eiswein's character to the dense concentration of the berry ingredients and a comparatively high degree of acidity

Cryoextraction sits outside the protected ice wine names. Germany's Weingesetz (§20) requires that the grapes used for Eiswein be frozen at harvest and at pressing, and Wine Spectator reported in 2013 that under German law the grapes must freeze on the vine and that artificial freezing is strictly prohibited. In British Columbia, the Wines of Marked Quality Regulation (B.C. Reg. 168/2018) requires Icewine grapes to have frozen naturally on the vine while the air temperature is -8°C or lower and to be pressed in a continuous process while the grapes are still frozen, and it refuses the Icewine category to any wine processed using an artificial method of concentrating sugar, including artificial refrigeration at a temperature below -4°C. The OIV's icewine definition likewise rests on cryoselection in the vineyard without recourse to physical procedures. Decanter reported that Argentina's Las Perdices Ice, made using cryoextraction, cannot use the term Ice Wine on its label.

• OIV icewine prescriptions: harvesting and pressing at a recommended temperature of -7°C or lower, a minimum potential alcohol in the must of 15% by volume (110° Oechsle or 25.3 Brix), and an acquired alcoholic strength of at least 5.5% by volume
• British Columbia Icewine must reach at least 32° Brix after each pressing and an average of at least 35° Brix across combined pressings, with residual sugar of at least 100 g/L at bottling, and its tanks may not be cooled below -4°C during fermentation and cold stabilization
• In the Loire, the Quarts de Chaume Grand Cru specification bans any thermal treatment of the harvest involving a temperature below -5°C, applying from the 2020 harvest; Decanter's Jim Budd reported that mechanical freezing or cryoextraction had been allowed there as an experiment and would be phased out

Sarah Jane Evans MW, in Decanter, presents cryoextraction as the answer if winters warm: just as grapes may be sprayed with botrytis spores to induce the infection, she writes, freezing will do the trick for ice wines, and Sauternes producers such as Château d'Yquem make use of it. Wine Spectator's 2013 report named New Zealand as a place where artificial freezing is practiced. In Argentina, Decanter reported that Viña Las Perdices made Las Perdices Ice, a sweet Malbec from Mendoza, using cryoextraction, with 10,000 bottles made in its first two vintages. For naturally frozen wine, Wines of Germany dates the first documented German ice wine to 1830, when winegrowers near Bingen in Rhineland-Hesse discovered on February 11 that a sweet must could be obtained from frozen grapes.

• Wines of Germany reports that a 1982 amendment to the German Wine Law raised Eiswein to an independent attribute, with a minimum must weight of 110 to 128° Oechsle depending on the growing region
• Wine Spectator reported that 470,000 liters of ice wine were declared in Rhineland-Palatinate after the poor 2011-12 winter and more than 90 percent was rejected by state inspectors; the same 2013 report said a new state law requires growers to report their intended ice wine grapes by Nov. 15

Wines of Germany describes ice wine as a winemaker's gamble that carries the risk of total loss, and reports that only about 5-10% of the original harvest quantity is bottled as ice wine on average, with harvests often only between 300 and 500 liters per hectare. Wine Spectator (2013) put the average at 100 to 200 liters of ice wine per acre, compared to more than 4,000 liters for other wines.

• Wine Spectator's Dr. Vinny notes that if the freeze does not come quickly enough the grapes can rot, and if it is too severe no juice can be extracted
• In Decanter, Slovenian producer Slavko Prapotnik called -7°C a prescribed minimum in Slovenia but not enough for quality ice wine, and wine writer Robert Gorjak said the timeframe is shifting toward January

Primary sources (the OIV, German and British Columbia law texts, the INAO, and Wines of Germany): https://www.oiv.int/standards/international-code-of-oenological-practices/part-ii-oenological-treatments-and-practices/grapes, https://www.oiv.int/standards/international-code-of-oenological-practices/part-i-definitions/special-wines, https://www.gesetze-im-internet.de/weing_1994/__20.html, https://www.bclaws.gov.bc.ca/civix/document/id/complete/statreg/168_2018, https://www.winesofgermany.com/our-wine/wine-products/wine-product/418/eiswein, https://extranet.inao.gouv.fr/fichier/3.11-CDC-Quarts-de-Chaume-modifi%C3%A9.pdf. Secondary: https://www.decanter.com/features/sauternes-and-tokaji-offering-affordable-and-alternative-wines-246834/, https://www.winespectator.com/articles/whats-the-story-with-eiswein-5339, https://www.winespectator.com/articles/german-ice-wine-rules-tightened-49351, https://www.decanter.com/wine-news/fury-and-charges-of-egotism-as-loire-s-baumard-challenges-grand-cru-32645/, https://www.decanter.com/wine-news/argentina-exports-first-ice-wine-66131/. Last verified 2026-09-28