A frosty winter's day in Canada's Niagara region invites scores of hardy workers to brave the elements and head for the vineyard. Cold winds can make the temperature seem like minus 40 degrees Fahrenheit [-40°C]. Why are these harvesters so willing to go out in such harsh weather to gather frozen, shriveled grapes that are as hard as marbles? Because those withered grapes yield an intensely sweet wine with the color of gold icewine.
Timing and Temperature
American writer Mark Twain called accident “the greatest of all inventors.” So it was in Franconia, Germany, in 1794 when vintners pressed juice from frozen grapes after an ice storm. The grapes yielded a wine with a remarkably high concentration of sugars; yet, its high acidity balanced the wine's sweetness. Producing icewine on a yearly basis, though, presents special challenges to the wine maker. The temperature must be below 19 degrees Fahrenheit [-7°C] for several days if the juice is to freeze properly. A quick thaw will dilute the sweet juice. If it gets too cold, the hard grapes will yield very little when pressed. “It's tricky,” says one Niagara wine maker. “It has to be just right.”
The climate in southern Canada, especially in the Niagara region, is ideal for producing icewine. Temperatures will predictably fall below 19 degrees [-7°C] sometime between November and February. Wine makers have been especially successful in making icewine from Riesling and Vidal grapes, although other varieties have also been used. While other countries also produce icewine, Canada has become the world's largest producer, garnering high awards at several international wine competitions.
Why So Sweet?
The intense sweetness of icewine is due to the concentration of sugars within the grapes' juice. Grapes, which are 80 percent water, are picked and pressed while frozen. Vintners must press the grapes outside or keep the winery doors open to ensure that the grapes stay frozen. Most of the water, which freezes at a higher temperature than the sugars, is trapped as ice. So when the frozen grapes are pressed, the juice that comes out has a high concentration of sugars. This juice is, as one wine columnist put it, “miraculously sweet.”
Interestingly, although Canada is known for its formidable winters, Niagara is more southerly than the famous Burgundy region in France. Therefore, with many hours of sunshine and high temperatures in July-when the vines' growth is the most active-Niagara is ideally situated for producing an icewine with a high concentration of sugars. In the autumn the climate varies considerably, which dehydrates the grapes and intensifies the sweetness.
Tasting “Liquid Gold”
Two pounds [1 kg] of normal grapes will generally yield one 750 milliliter bottle of wine. However, depending on wind and on winter sunshine, two pounds [1 kg] of dehydrated icewine grapes may only yield one fifth of a bottle or even less! Therefore, icewine can be quite expensive and is often sold in half-bottles (375-milliliter bottles).
According to one wine maker, icewine's bouquet “recalls lychee nuts,” while its flavor includes “tropical fruits, with shadings of peach nectar and mango.” Though the sweetness and intensity of flavor may initially be overpowering, “the balance is achieved by the acidity, which gives a clean, dry finish.”
The popularity of icewine is not limited to Canada. Exported widely, especially to East Asia, icewine has been embraced as a sweet alternative to cognac.
Interestingly, Niagara wineries have reported that several individuals have volunteered to participate in the frigid harvest. Their wages? A half-bottle of “liquid gold.”
