How can some wines be "sulfite free" if sulfites are a natural byproduct of fermentation?

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Dear Dr. Vinny,

How can some wines be “sulfite free” if sulfites are a byproduct of fermentation?

—Francine C., Amagansett, N.Y.

Dear Francine,

You’re correct that sulfites are a byproduct of fermentation, which means that there is probably no such thing, strictly speaking, as a “sulfite-free” wine, though there are wines without any detectable sulfites.

Sulfites are found in all kinds of foods—they’re in other fermented products like beer and cheese, along with dried fruit, molasses, canned tuna, bacon, pickles, jams and olives. If you can enjoy a handful of raisins and not have asthma-like symptoms, hives or swelling afterward, that means you’re lucky enough to not be part of the approximately 1 percent of the population who are sensitive to sulfites.

Many winemakers choose to add sulfites to wine, beyond what occurs in the fermentation process, to help protect it from spoiling. But some winemakers—including those following organic protocols—do not.

You may have seen that wines sold in the United States since 1987 are required to carry a “contains sulfites” warning on the label (if they have from 10 to 350 parts per million of sulfites). The same wine sold elsewhere doesn’t necessarily come with this warning. I think this creates a lot of confusion, leading folks to wonder if sulfites are to blame for their headaches or hangovers. I think the fact that “sulfites” also sounds a lot like “sulfates” is another point of confusion.

Wines with less than 10ppm are not required to carry the sulfite warning, and some winemakers do their best to filter out sulfites (mostly by doing a lot of racking), getting them down to an amount that’s not detectable by current testing protocols. That might change if testing went down to parts per billion or trillion. To give you some context, TCA (the chemical compound 2,4,6-trichloroanisole, which is responsible for so-called “corky” wines) is detectable at just a few parts per trillion. It might be the equivalent of grains of sand in a swimming pool, but it’s detectable.

So, while there are labels promoting “sulfite free” or “no sulfites detected,” that’s a technicality, as there are very likely still sulfites present.

—Dr. Vinny

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