[Editor's Note: For those of you not familiar, an ice wine is a wine made from the juice of frozen grapes. Most of the water in the grapes is frozen but the sugar is not. When a winery runs them through the grape crusher and grape presses, the result is a very, very sweet grape juice that will make a wine with high alcohol and a lot of flavor.]
I have some lake niagara grapes that I am interested in trying to make an ice wine recipe. They are in the freezer currently. Do I make it the same as a grape wine or is there some other step in the process that I have to do? Any info you can give me would be appreciated.
What you are actually attempting to make is an icebox wine not an ice wine. The difference being, you are using artificial cold to freeze the grapes as opposed to leaving them on the vine and waiting for Mother Nature to do the freezing for you.
To answer your question, there is really not too much difference between making an ice wine and making any other grape wine. The basic steps are the same, except for the fact that you will be putting the grapes through a grape crusher and your grape presses before fermentation. The skins will not be in the fermenter at all. This is because the ice is with the pulp at this point.
The whole goal with ice wines is to get as much sugar out of the grapes while getting as little of the water. Freezing the grapes works out good for this purpose. Water freezes at a higher temperature than sugar does, a phenomenon known as fractional crystallization.
By bringing the grapes down in temperature to around 15F. to 20F. you are freezing mostly water. The grapes are then ran through the grape crusher and pressed as quickly as possible. An extremely sweet juice comes out of the press while the skins, pulp and ice stay in the press and are later discarded.
Having a refractometer to monitor the sugar concentration of the grape juice at this stage would be beneficial. You are looking to get a brix reading of at least 35 degrees. This is the minimal level used by commercial wineries in Canada -- Canada being the biggest produce of ice wine in the world.
I hope this information helps you out. Just remember that it is really no different than how to make white wine, only the grapes are cold and stiff.