Icewine: freezing grapes and other feisty ways to drink sweets

by Mary Jacobson, MD and Lynn Gretkowski, MD

How is it that some wines are sweet and other wines are dry?  Let’s consider our sweet dessert wines like icewines, Vin Santos, Ports, Madeiras, Sauternes, and Tokajis.

Other than the grape varietal, it’s the grape’s sugar content and the process of how that sugar level is achieved that takes these wines on their respective journeys and gives them their delightful, unique sweetness.

Grapes can concentrate their sugars by a long hang time on the vine, which optimizes their ripening. Grapes can also have a symbiotic relationship with a native vineyard fungus, called botrytis that concentrates sugar by pulling the water out of grapes, essentially transforming them into wine grape raisins. Freezing and frost exposure dries out grapes, eventually leading to the production of Eiswein—icewines. Ports are sweet due to the arrest of fermentation of super ripe grapes by adding neutral spirits that are high in alcohol and kill the yeast.

In Europe, wines can become sweet by the addition of sugar or chaptalization during the fermentation process. This may be necessary, especially in places like Germany where high sugar levels are difficult to achieve in grapes due to lower temperatures and shorter daylight. Fermentation is arrested when balance is achieved.

Icewines in Canada and German Eiswein may start off with the traditional Vitis vinifera grapes that go on to become dry wines or even French hybrids commonly found in the Eastern United States. The French hybrids, uniquely adapted to weather challenges such as cold and humidity, enable these grapes to achieve peak potential for ripening.

So, either freezing, drying via freezing, or lying grapes out on straw mats or stopping fermentation before it is completed are the main methods to create sweetness.

Dessert wines are niche products that particularly glow in the cold winter months and pair well with fresh cheeses and dried fruits, puddings, and toffees. In general, the lighter the dessert, the lighter the wine, the darker the dessert, the darker the dessert wine. High acid in late harvest Riesling cuts through soft mild cheeses. Madeira pairs well with nuts and fruitcakes. Trifles may go well with the sweet sparkle of Prosecco, a fig tart with Port. Either way, it’s the perfect time of year to give these wines a chance and decide on your favorite variation on sweetness!

Mary Jacobson, MD and Lynn Gretkowski, MD are the WineDoctors ( They are committed to promoting an understanding of the impact of wine on health by providing transparent, accurate information as it relates to moderate wine consumption. They also produce a line of handcrafted, boutique wines.

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