Ice Wine / Eiswein — Frozen Vine Harvest & Cryoconcentration

Ice wine is a dessert wine made exclusively from grapes that have frozen naturally on the vine and are harvested and pressed while in that frozen state. The process separates dissolved sugars, acids, and flavor compounds from pure water ice, concentrating them to extraordinary levels. Germany and Austria classify Eiswein within the Prädikatswein system; Canadian Icewine is regulated by the Vintners Quality Alliance (VQA) in Ontario and British Columbia, with strict harvest temperature requirements and a prohibition on artificial freezing.

• German Eiswein: minimum must weight of 110 to 128 degrees Oechsle depending on the growing region; grapes must be harvested and pressed at -7°C or colder; Riesling is the flagship variety, with Silvaner also used
• Canadian Icewine (VQA): harvest must occur at -8°C or below; minimum 100 g/L residual sugar at bottling; artificial freezing is strictly prohibited; VQA monitors harvests in real time
• British Columbia Icewine is regulated under the Wines of Marked Quality Regulation administered by the BC Wine Authority, with the same -8°C threshold as Ontario
• Cryo-extraction (artificially freezing harvested grapes in a cellar) is used in some countries to simulate the process but is not permitted to be labeled as Eiswein or Canadian Icewine

When grapes freeze at -7°C or below, water crystallizes into ice while dissolved solutes such as sugars, acids, and amino acids remain in a liquid state due to their lower freezing points. This phenomenon is called cryoconcentration. Pressing the frozen fruit gently separates the concentrated liquid from the ice matrix. Only about 10 to 20% of the liquid in the frozen grapes is extracted for ice wine, compared to the far higher yields of a standard harvest. This mechanical concentration differs fundamentally from botrytis dehydration, preserving fresh acidity and aromatic compounds.

• The sugars and other dissolved solids do not freeze, but the water does, allowing a more concentrated grape juice to be pressed from the frozen fruit
• Ice wine press runs can take four to five days, far longer than an equivalent dry wine press, because the grapes are pressed multiple times and temperature must remain low throughout
• Grapes that re-thaw will spoil quickly because ice crystals destroy cell walls, so harvest must be completed within a few hours on the first sufficiently cold morning
• Harvesting in the early morning hours when temperatures are lowest is standard practice; producers often use electric lighting powered by portable generators to work before sunrise

Ice wine production is a high-stakes gamble on weather. Winemakers in frost-prone regions such as Germany's Mosel, and Canada's Niagara Peninsula and Okanagan Valley, leave selected vineyard blocks unharvested through autumn and into winter, hoping for a reliable deep freeze. If frost never arrives or mildew destroys the fruit first, the entire crop is lost. In Germany, ice wine has become increasingly rare due to climate warming. Canada's Niagara Peninsula enjoys the advantage of consistent continental winters, meaning every winter since the late 1980s has been cold enough for at least some icewine harvest.

• Riesling is the flagship variety for German Eiswein, prized for aromatic intensity; its thick skins offer some protection during freeze-thaw cycles, though bunch stems can degrade and drop fruit
• In Canada, the hybrid Vidal is the dominant icewine variety due to its thick skin, high natural acidity, and resistance to the cold; Riesling and Cabernet Franc are also widely used
• Canada is the world's largest icewine producer because its continental winters deliver reliable sub-8°C conditions, a regularity that European regions cannot match
• Climate change has made Eiswein vintages significantly less common in Germany in the 21st century compared with the 1980s and 1990s, increasing scarcity and prices

After frozen pressing, ice wine juice presents an extreme fermentation challenge. The sugar concentration is so high that it is osmotically stressful for yeast cells, causing many to die before fermentation is complete. Osmosis-tolerant yeast strains are required to achieve even a modest degree of fermentation. Fermentation is slow, often lasting three to six months, and typically stalls naturally at 7 to 11% ABV, leaving massive amounts of residual sugar. Winemakers may stop fermentation deliberately through cold and filtration once the desired sugar-alcohol balance is achieved. Most ice wines are bottled in small formats to emphasize their luxury status.

• The juice is so sweet, typically 32 to 46 degrees Brix at pressing, that fermentation can take anywhere from three to six months to run its course
• Osmosis-tolerant yeast strains are essential for ice wine fermentation; standard yeasts founder under the high sugar stress, risking stuck fermentation and elevated volatile acidity
• Fermentation is typically stopped through chilling and filtration once sensory balance is achieved; the degree of final fermentation is determined as much by palate assessment as by numbers
• Bottling predominantly occurs in 375 mL half-bottles, reflecting both the tiny yields and the wine's luxury positioning

Cryoconcentration produces wines of remarkable sensory intensity. The absence of botrytis means ice wine retains a pristine, fruit-driven character rather than the honeyed, mushroomy complexity of Sauternes or Tokaji. The titratable acidity in ice wine very often exceeds 10 g/L, providing the structural backbone that prevents the intense sweetness from being cloying. German Eiswein tends toward crystalline, citrus-led Riesling character with slate mineral notes. Canadian Icewine, particularly from Vidal, emphasizes tropical fruit, peach, apricot, and honey richness. Both styles have genuine aging potential, with top examples evolving over decades.

• Residual sugar typically ranges from 150 to 250 g/L, balanced by titratable acidity that very often exceeds 10 g/L, far above the norm for dry Riesling
• Primary aromas include peach, apricot, mango, lychee, and honeysuckle; no botrytis character such as mushroom, beeswax, or marmalade should be present in a well-made ice wine
• Alcohol is restrained at roughly 7 to 11% ABV, allowing fruit, sugar, and acid complexity to dominate the palate without heat
• Top Riesling-based ice wines, particularly from Germany's Mosel and Canada's Niagara Peninsula, have demonstrated the capacity to age and evolve positively for several decades

Germany's ice wine tradition is anchored in the Mosel, with estates such as Dr. Loosen (Bernkastel) and J.J. Prüm (Wehlener Sonnenuhr) producing Eiswein when conditions allow. In Canada, Inniskillin Wines on the Niagara Peninsula pioneered commercial icewine production with their first successful vintage in 1984, using protective netting after birds had destroyed their 1983 attempt entirely. Inniskillin's 1989 Vidal Icewine then won the Grand Prix d'Honneur at Vinexpo in Bordeaux in 1991, bringing Canadian icewine to global attention. The first icewine in Canada was actually produced earlier, in 1972, by Walter Hainle in British Columbia's Okanagan Valley.

• Dr. Loosen (Mosel, Germany): produces Eiswein from 100% Riesling when conditions allow, sourcing from sites in Urzig and Erden; one of the Mosel's most prominent producers
• J.J. Prüm (Mosel, Germany): founded 1911; produced its first Eiswein with the 1949 vintage from the famous Wehlener Sonnenuhr vineyard site
• Inniskillin Wines: founded 1975 by Donald Ziraldo and Karl Kaiser in Niagara-on-the-Lake; first commercial icewine in 1984; won Grand Prix d'Honneur at Vinexpo 1991 for its 1989 Vidal Icewine; now owned by Arterra Wines Canada
• Walter Hainle produced the first icewine in Canada in the Okanagan Valley in 1972, predating Inniskillin's commercial production by over a decade