Ice Wine / Eiswein Harvest (Below -8°C Threshold)

Ice wine (Eiswein in German) is a dessert wine produced from grapes that freeze naturally on the vine, then are harvested and pressed while still frozen. The technique is believed to have originated accidentally in Franconia, Germany, around 1794, and the first well-documented Eiswein harvest occurred on February 11, 1830, in Dromersheim near Bingen in Rheinhessen. Throughout the 19th century, Eiswein harvests were rare events, dependent on freak weather. Production increased meaningfully only after the invention of the pneumatic bladder press and from 1961 onward. Canada entered the story in 1973 when German immigrant Walter Hainle produced 40 litres of icewine in British Columbia's Okanagan Valley, and Inniskillin's commercial success from 1984 onward transformed Canada into the world's leading producer.

• First believed Eiswein production: Franconia, Germany, around 1794; first well-documented case: Dromersheim, Rheinhessen, February 11, 1830
• Eiswein classified as an independent Prädikat under German wine law in 1982, with minimum must weights measured after freezing
• VQA Canada standard established in Ontario in 1988, requiring harvest at -8°C or colder and a minimum of 35° Brix
• Canada is now the world's largest icewine producer, with Ontario accounting for over 90% of Canadian production

When grapes freeze at -8°C or below (Canada) or -7°C or below (Germany), the water inside the berry crystallises as ice while sugars, acids, and other dissolved solids remain liquid due to their lower freezing points. This process, known as cryoconcentration, means that pressing the frozen grapes yields a small volume of intensely concentrated must. On average, only about 5-10% of the original harvest quantity is ultimately bottled as ice wine. The juice is so rich in sugar that fermentation can take anywhere from three to six months, and German Eiswein often reaches only around 7% alcohol while retaining very high residual sugar and acidity.

• Cryoconcentration: water freezes and is removed as ice crystals during pressing, concentrating all dissolved solids in the remaining juice
• Juice yield is dramatically reduced: approximately 5-10% of the original harvest quantity is bottled as finished icewine
• Canadian VQA minimum harvest temperature: -8°C; German Eiswein minimum: -7°C, with natural on-vine freezing required in both countries
• German Eiswein alcohol is often around 7% ABV due to the extreme osmotic pressure resisting yeast fermentation, with very high residual sugar retained

Ideal icewine grapes possess high natural acidity, resilient skins, and the structural integrity to hang on the vine through autumn into deep winter without rotting. In Germany, Riesling is considered the benchmark variety for Eiswein, prized for its aromatic complexity and mineral-driven acidity. In Canada, the French-American hybrid Vidal dominates Ontario production due to its thick skins and natural resistance to winter damage, while Riesling and Cabernet Franc are also widely used. Crucially, premium icewine grapes should ideally be free of botrytis cinerea. Unlike Sauternes or Trockenbeerenauslese, where noble rot is essential, healthy undamaged grapes are required to survive intact until the freeze arrives.

• Riesling: Germany's benchmark Eiswein variety, delivering aromatic complexity, mineral character, and high natural acidity
• Vidal Blanc: Ontario's most-used icewine grape, valued for its thick skins and winter hardiness
• Cabernet Franc: widely used for red icewine in Canada, especially in Ontario's Niagara Peninsula
• Botrytis-free grapes are preferred; noble rot compromises the vine's ability to survive extended hang time and dulls icewine's characteristic clean fruit freshness

Natural icewine production requires cold, predictable winters in wine-growing regions capable of reaching the legal freeze threshold reliably. Ontario's Niagara Peninsula is widely regarded as the only wine region in the world where the required freeze can be expected every vintage, which is why Canada produces more icewine than all other countries combined. Germany's Mosel and Rheingau produce Eiswein only when conditions cooperate, which historically occurs once every five years or so, adding scarcity value. Harvest typically occurs between December and February in the Northern Hemisphere, and grapes must be picked and pressed while still frozen, meaning harvest often happens at night or in the early pre-dawn hours before temperatures rise.

• Niagara Peninsula, Ontario: the only wine region in the world where the required freeze for icewine can be expected reliably every year
• German Mosel and Rheingau: Eiswein conditions occur only periodically, historically roughly once every five years on average
• Harvest timing: typically December through February in the Northern Hemisphere; grapes must be picked and pressed while still frozen
• Climate change is reducing Eiswein frequency in Germany, increasing scarcity and driving prices higher for German examples

Icewine fermentation presents unique challenges. The extremely high sugar concentration creates intense osmotic pressure that stresses yeast, slowing fermentation dramatically. Canadian icewine juice runs at approximately 32-46 Brix at pressing, and fermentation typically takes three to six months. German and Austrian producers are forbidden from adding sugar (chaptalisation is prohibited for all Prädikatswein), and Canadian VQA regulations similarly prohibit chaptalization for icewine. The high natural acidity of the finished wine (typically well above 6.5 g/L) acts as a natural preservative, reducing the need for heavy sulphur additions. Most icewine is aged in stainless steel to preserve its fresh, primary fruit character.

• Chaptalization is prohibited: German Prädikatswein rules forbid sugar addition, and Canadian VQA icewine regulations do the same
• Fermentation duration: typically three to six months due to extreme sugar concentration and osmotic stress on yeast
• Natural acidity above 6.5 g/L is typical in finished icewine, helping preserve the wine and balance residual sweetness
• Stainless steel aging is the norm to protect delicate aromatics; oak is rarely used in premium icewine production

The defining moment for Canadian icewine came in 1991, when Inniskillin's 1989 Vidal Icewine was awarded the Grand Prix d'Honneur at Vinexpo in Bordeaux, the fair's highest award. Inniskillin, founded in Niagara-on-the-Lake by Donald Ziraldo and Karl Kaiser, made its first commercial icewine in 1984 after losing an entire crop to birds in 1983. German benchmarks include estates in the Mosel, Rheingau, and Nahe that produce Riesling Eiswein in the rare vintages that provide the required freeze, with producers such as J.J. Prüm and Dönnhoff recognised for exceptional examples. It is important to note that Tokaji Aszú is categorically distinct from icewine: it is produced by macerating botrytis-affected dried berries in base wine, an entirely different process.

• Inniskillin 1989 Vidal Icewine: Grand Prix d'Honneur at Vinexpo Bordeaux 1991; the award that established Canada as a global icewine leader
• Inniskillin's first commercial icewine was produced in 1984 by co-founder Karl Kaiser after protected netting saved the crop from birds
• German Eiswein benchmarks: Mosel, Rheingau, and Nahe estates produce Riesling Eiswein when rare conditions allow, approximately once every five years
• Tokaji Aszú is not icewine: it is a botrytis-concentrated wine made by macerating dried aszú berries in base wine, a categorically different process from cryoconcentration