Does a wine contain traces of substances used in the fining process, such as gelatin or sturgeon bladder?

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Dear Dr. Vinny,

If a wine was fined with gelatin or sturgeon bladder, do any of these fining agents remain in the wine?

—Yosef, Canton, Ohio

Dear Yosef,

To put your question in context, I'll first explain that fining is a process where substances are added to a wine to attract solids and proteins, so they clump together and fall to the bottom. Then the wine is separated from these solids in a process called racking, leaving the solids—and the fining agents—behind.

Winemakers can use several different fining agents. They include gelatin and sturgeon bladder, as you mention, as well as egg whites, milk casein, seaweed and clay. Technically, no trace of these fining agents should remain in the finished wine, but as a safety precaution, some countries require allergen labeling that indicates traces may remain if the product was used in fining wines. (In the United States, allergen labeling is voluntary on wines.) I know some vegans who still avoid wines that use animal products in any way, and some fining agents are barred from use in the making of kosher wines.

—Dr. Vinny

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