Winemakers must harvest the grapes under precisely the right weather conditions and extract the high-sugar juice before they thaw. The slightest variation in temperature can doom an entire crop, but vintners skilled in the process can charge $4 per ounce or more.
Some winemakers now aim to make the beverage less expensive by limiting the uncertainty that can drive up the price. They harvest the grapes earlier in the fall and age them in freezers that simulate the chill takes place under ideal outdoor conditions. They say the technique leads to ice wine that's less expensive and more consistent in flavor.
A quality Riesling ice wine from New York can cost $75 to $100, while the artificial version would run about $50, said Jim Trezise, president of the New York Wine & Grape Foundation.
"If you're going pick the grapes and put them in the freezer, you can do that on your own schedule," Trezise said. "If you're going to pick according to nature's schedule, you literally have to have crews ready to go out at 5 in the morning when the temperature is just right. So the risk is greater and the labor costs greater to make naturally formulated ice wine."
Purists insist nature can't be improved upon and say half the fun of a great ice wine is being able to taste the winemaker's artistry and skill.
Tom Pennachetti, a winemaker with Cave Spring Cellars in Jordan, Ontario, said freezing grapes indoors defeats the purpose of making ice wine. There's a difference, he says, between letting each grape be exposed to the natural variations of outdoor temperatures and boxing up bunches in freezers where grapes in the center of the pack don't get the same exposure as those near the edges.
"Some people say what's the difference? That's a big difference," Pennachetti said.
The question in the industry is whether consumers will notice the difference. Some believe the cheaper artificial ice wines will allow wineries to expand their market to include less-affluent customers. Others believe loyalists, such as 83-year-old Paul Opichka, will be turned off.
The Milwaukee man was one of about two dozen people who braved frigid Wisconsin temperatures recently at the Wollersheim Winery in Prairie du Sac, helping pick frozen St. Pepin grapes for next year's ice wine.