I have the belief we can make world class Ice Wine here in Vermont. Currently the mecca for Ice Wine is the Niagara Bench (the land lying above the south shore) of Lake Ontario on the Canadian portion of the lake. There in Ontario, due to the influence of the “warm” waters of Lake Ontario, harvest must frequently wait until January, or sometimes February, before they get a day cold enough to harvest. Here in VT, Lake Champlain is also a moderating influence, but not quite as much. The rule of thumb for Ice Wine is that the harvest can only take place at a temperature no warmer than -8C (17.6F). The latest we have harvested here at Shelburne Vineyard has been the 29th of December. The grapes are in much better shape the earlier the harvest. Late fall and early winter freeze and thaw episodes really do a job on the grapes. This, along with all the nibbling (actually devouring) the birds and raccoons do, makes for a very precious and challenging harvest.
The Ice Wine grape variety of choice is Vidal Blanc . This is because:
----Vidal clusters hold fast to the vine under winter conditions and
----the grapes retain a considerable amount of acidity when ripe.
A quality sweet wine needs a balance of natural sweetness and natural acidity.
Many ask why we wait for a serious freeze before harvesting. At 17.6F the high sugar content liquid in the grape is still not frozen as very sweet juice freezes at a lower temperature than water. Pressing a Vidal grape during normal harvest time would produce juice with a sugar content of 21 to 22% by weight. When we begin pressing the partially frozen grapes the juice that flows first is over 40% by weight sugar. The longer we press the lower the sugar content of the juice as the frozen water portion of the grape begins to thaw. We can pick the sugar point to stop at.
We harvested on Sunday, Dec 18 2011, at 10F. It was a crisp, bright, windless morning. We harvested 900 pounds of grapes. Ethan our winemaker and his crew pressed until the entire juice content was 34.5% by weight. (34.5 Brix). The acidity was 9.7 grams/liter (0.97%) and the pH was 3.0. We stopped pressing after 27.5 hours and produced 56 gallons of juice. Marathon over!
The next step is introducing (“pitching”) the yeast. Due to the high sugar content, fermentation is a very slow process. We will monitor the progress and stop fermentation when the residual sugar is around 12%. This will make a nice dessert style wine with approximately 11% alcohol.
Over the last two seasons we have increased our acreage of Vidal Blanc by 200% so we hope to have more Ice Wine available ...when these vines mature....over the next few years.Since it seems like we can never make enough!