Harvesting the grapes for ICEWINE -Peller Estates Team

During Icewine season, wineries and grape growers keep a careful watch on the weather forecast looking for an optimum stretch of temperatures between -10 and -12 °C ( standards may vary from province to province). This temperature range will produce juice in the range of 35 to 39 ° Brix (roughly equivalent to the percent sugar in the juice). Typically, a period of at least 6 hours is needed to harvest and press the grapes – and it is usually an overnight job. Most small and medium sized wineries harvest by hand, often with volunteers who are enthusiastic Icewine lovers and want to experience the harvest first hand. Warm clothing is required. Mechanized harvesting has been developed very recently and is now an option for larger vineyards.

Once the grapes are harvested, they are pressed in small hydraulic presses under much higher pressure than normal for grapes harvested in the regular season. Because the grapes are frozen, most of the mass is water, and is left behind as ice in the press. Only a small amount of concentrated juice is extracted. Juice yields for Icewine grapes are much lower than for table wines – with average yields of 500 litres for each acre netted, or approximately 15% of the expected yield for grapes harvested for table wines. This reflects both the losses in grape volume from dehydration while the grapes hang and losses to hungry birds and other animals.

Icewine juice is very sweet and can be difficult to ferment. High sugars can create a hostile environment for the yeast and fermentation stops early, leaving relatively low alcohol and high sugar levels in the finished wine.

Its a cold night when the harvest begins all hands must answer the call.

Harvesting at Paradise Ranch

 

The major requirement of icewine is cold temperatures. In order to harvest the grapes qualifying standards must be met in some regions that is easier to be achieved than others. Canada is more suited to producing icewine than for example, France. In Ontario weather conditions in the Niagara peninsula are more suited to freezing temperatures than southern Okanagan. When the standards are met and the call comes, the rush is on to harvest and press the grapes. Icewine must be produced exclusively from grapes that have been harvested, naturally frozen on the vine, and pressed in a continuous process while the air temperature is -8° Celsius (17.6°F) or lower. Icewine grapes are often harvested during the night to guarantee a temperature below -8° Celsius. Its an all hands on deck operation.

The wineries usually wait until it is -9° Celsius to -11° Celsius ( 16F -12F) Ideal parameters for pressing the juice are between 38°-42° Brix juice yield around 159L per tonne for vidal and 125 L per tonne for riesling, ideal titratedable acidity of 10-12 g/l tartic acid and PH between 3.1 and 3.3. Vineyards yield should be no more that 7 tonnes per acre for Vidal and 5 for Riesling. Riesling and Vidal are the most popular icewines in Ontario

The ideal or optimal harvest time is mid December to mid January. Early freezing does not produce the highest quality juice. If the freeze comes too late the grapes may be dehydrated. More complex flavours may occur if the grapes are not picked until the second freeze, allowing for a freeze-thaw-freeze cycle

Temperature is not the only factor that may harm the icewine harvest. Birds like to feed on the grapes. To protect the grapes devices are used to scare off the birds including the use of propane cannons. Netting is also used and is perhaps the best method.

Both Ontario and British Columbia icewine standards are by the Vintners Quality Alliance - VQA - It is similar to other regulatory systems in place in such countries as France (AOC), Italy (DOC), and Germany (QmP), and ensures the consumer of high quality Canadian wine.

Frozen grapes going into the Crusher at Summer Hill Pyramid Winery. Kelowna British Columbia

 

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