I heard there's no way to tell if a wine labeled "Chardonnay" is really 100 percent Chardonnay. Is that true?

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Dear Dr. Vinny,

A friend told me that some wines labeled "Chardonnay" actually contain a blend of Chardonnay and Sauvignon Blanc. Moreover, he says that there is no way for a consumer to determine whether a wine is 100 percent Chardonnay or not! Is that true?

—Atsuko, Chicago

Dear Atsuko,

Yes, it's true, and it's not just for Chardonnay. Laws vary around the world, but if an American wine is called by a varietal name—in this case, Chardonnay—you can be assured it has at least 75 percent Chardonnay. The rest of the blend can be comprised of other grapes (Sauvignon Blanc is one example). Some winemakers blend in other grapes to make a stronger, more complex wine, or to add an element they feel is missing—say, color or an aromatic component. Others like to focus on single-vineyard bottlings, and a vineyard may have more than one grape variety planted. You'll find that many producers are pretty up-front about what types of grapes go into their wine, and if it's not on the back label, the information might be on their website.

—Dr. Vinny

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