#62 We Pick Ice Wine Grapes: When & Why

We said harvest was over, but that did not include the Riesling left out for Ice Wine.

In January, 2024 we plan to pick the last Riesling from the 2023 vintage. We are waiting for exactly the right time.

But, what—exactly—is the “right time?”

Mainly, we want the grapes to de-hydrate. That is, lose water and get wrinkly. In the picture below, taken in mid-December, they have de-hydrated but not enough to yield the concentrated flavors that we are looking for.

The de-hydration needs to progress until most of the grapes have really shriveled. Ideally, at this point, they have also become brown and “raisin-like.” This “browning” is the same browning that you see when you caramelize an onion or sear a steak. Known in the culinary world as “the Maillard reaction,” this process creates flavors that remind some people of honey, caramel or butter-scotch.

But that is still not enough. We also have to wait until the temperatures hover around 15 degrees Fahrenheit. At that temperature, any water remaining in the juice will freeze (ie, turn solid); and the non-water component of the juice will remain liquid. (It is denser, like an anti-freeze.) When we press that semi-frozen, slushy cluster, the liquid portion, the most concentrated juice, presses out. The water, which is now frozen, will not press out.

This process yields a juice that is even more concentrated than before, due to the freezing of what little water remained in the juice. If the temperatures fall too far below 15 degrees, the entire berry freezes and nothing will press out. At a higher temperature, like 25 degrees, the remaining water will not have frozen.

So it is usually in January that we pick, when: 1) the berries have de-hydrated sufficiently; 2) they have undergone the Maillard reaction; and 3) when the temperatures reach 15 degrees.

Ice Wine will age for 100 years or more. As it ages, its flavors change from fresh fruit to dried fruit, and it takes on a “nutty and earthy” quality. An older Ice Wine tastes like nothing else in the world. It pairs well with blue cheese. And it is made in only a few places in the world. One of them is the Finger Lakes.