|
|
 |
Ice Wine
During the holidays, you may well decide to toast the New Year with a glass of champagne or drink some wine with your turkey, but how about sipping some ice wine with your fruitcake?
 “Ice wine is an intense wine,” says Dr. Hennie J.J. van Vuuren, Director of the Wine Research Centre at the University of British Columbia. “It’s a truly exquisite wine, but for producers, making it reliably and in sufficient quality is a major challenge.”
Ice wine is known as old man winter’s gift to wine lovers because the grapes are left on the vine until they freeze and the sugars concentrate, ideally at temperatures of -8°C to -13°C. But for producers, contending with warm spells, wind, hail and hungry birds is only the beginning of the challenge to coax the winter treasure into bottles. This fermented, unctuous, sweet nectar can only be called ice wine if it follows precise regulations (in Canada, set by the Vintners Quality Alliance, or VQA). These stipulate no artificial freezing, a minimum Brix (a measurement of the wine’s sugar content) of 35 degrees and a maximum of 1.3 g of volatile acids per litre. Too much volatile acid, and the ice wine becomes unpleasantly sharp.
“The highly concentrated grape ‘must’ (the freshly crushed juice, including pulp, skins and seeds) presents a major hurdle for wine yeasts which have to ferment the must. The ice wine industry all over the world has problems with controlling production of volatile acids by the yeast cells,” explains Dr. van Vuuren. An expert in wine fermentations, the microbiologist studies how yeast cells adapt to stress.
Using high-density DNA micro arrays, the NSERC grantee discovered that certain strains of wine yeasts are more sensitive to stress (not the kind of stress caused by your in-laws during the holidays, but the osmotic stress from the high concentration of sugars) than others. More stress means more volatile acids.
Now he has now identified yeast strains that are better suited to ice wine production. Ice wines produced with these yeast strains are being subjected to rigorous sensory evaluation – for clarity, bouquet and, of course, taste.
“If our pilot scale fermentations work well this year, the selected yeast strains will be used in commercial production of ice wines in Canada.”
Canada is the largest ice wine producer in the world with 40 to 50 vintners in Ontario and British Columbia producing the liquid gold. With hints of lychee, mango, peach, passion fruit and honey, ice wine is best served with fruit, foie gras, cheesecake … and fruitcake.
Contact:
Dr. Hennie J.J. van Vuuren
Wine Research Centre
Faculty of Agricultural Sciences
University of British Columbia
Tel.: (604) 822-0418
Cell: (604) 417-7711
E-mail: hjjvv@interchange.ubc.ca
Web site: http://www.agsci.ubc.ca/wine/van_vuuren.htm
|
