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Dear Dr. Vinny,

My son gave me a home winemaking kit, and it included a can of red grape concentrate, yeast pills and a 5-gallon container. How is grape concentrate made?

—Matt F., Daytona Beach, Fla.

Dear Matt,

Those home winemaking kits are a fun way to learn a little bit about winemaking. Of course, commercial winemakers use fresh grapes picked at just the right moment, but since that’s not possible in a kit, grape concentrate is used.

Grape concentrate is made essentially the same way any fruit concentrate is made—you’ve probably had orange juice made from concentrate at some point. To concentrate a fruit juice, the water is removed through a process of heating the juice and letting the water evaporate. Of course, heating juice might give it a cooked flavor, so concentrate is made under reduced pressure, which if you remember from science class, lowers the boiling point.

As much as two-thirds of the water is removed from grape juice during the concentrating process. I’m guessing that the instructions for your home winemaking kit instruct you to add water to the grape concentrate, which will hopefully give a good approximation of fresh grape juice.

Grape concentrate isn’t only used by home winemakers. Even commercial winemakers use a grape concentrate brand known as Mega Purple.

—Dr. Vinny

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