Q: Can I reduce or eliminate sulfites in wine by adding hydrogen peroxide (H2O2) to my glass?—Emmy, Cambridge, Mass.
A: Health-conscious wine lovers may have come across products that claim to reduce sulfites in a glass or bottle of wine, usually using hydrogen peroxide (H2O2). Some of these products also claim to eliminate tannins using powdered egg whites. Do these drops work, and why would you want to reduce sulfites in the first place?
What Are Sulfites?
Sulfur dioxide (SO2) and related sulfur compounds play crucial antimicrobial roles in winemaking. Small amounts are produced by yeast during alcoholic fermentation, so there’s no such thing as a completely sulfur-free wine. Many winemakers also add small amounts of sulfur during fermentation or at bottling to protect wine from spoilage.
The chemistry of sulfur in wine can get fairly complicated, and it’s important to note that SO2 exists in several related forms. So while it’s common to talk about “sulfites” as a fixed entity in wine, the reality of what’s going on in your glass is more complex. (Note, however, that sulfates do not exist in wine.)
Do Sulfites Cause Wine Headaches?
It’s sometimes claimed that using H2O2 (or other products) to remove sulfites will prevent wine headaches. However, the science is quite clear: There’s no evidence that sulfur compounds in wine contribute to headaches, and they may even help prevent them.
There is recent evidence that quercetin, a polyphenol, may contribute to red wine headaches. A class of compounds called biogenic amines may also contribute to the problem. Headaches are also a classic symptom of hangovers, which are attributable to a simple cause: drinking too much alcohol too quickly.
It’s very rare, but some people do have an allergy or sensitivity to SO2. For those people, avoiding sulfites might make sense. However, symptoms of a sulfur allergy typically resemble those of hay fever. There have also been reports of sulfites (usually in food, like dried fruits or salad bars) triggering or exacerbating asthma attacks. Even if you suffer from this sensitivity, sulfites in wine almost certatinly aren’t to blame for your headache.
The bottom line is that for most people, there’s probably no good reason to attempt to remove sulfites from your wine.
Can Hydrogen Peroxide Eliminate Sulfites in Wine?
But let’s say you really want to reduce the amount of sulfites in your glass. Is it possible?
Theoretically, yes. H2O2 is an oxidizing agent that readily donates an oxygen atom to other molecules. Adding H2O2 to your glass or bottle of wine will oxidize some of the sulfur compounds, effectively reducing the amount of sulfites.
Dr. Andrew Waterhouse, emeritus professor of viticulture and enology at the University of California, Davis, told Wine Spectator that “one problem for consumers is that they cannot know the actual amount of SO2 in the wine.”
On his laboratory website, he suggests adding one-forth of a teaspoon of three percent H2O2 to remove the sulfites in a typical bottle (around 80 mg/L of total SO2). Most H2O2 products on the market recommend adding a few drops to a glass, which roughly tracks with Dr. Waterhouse’s recommendation. But the amount of SO2 in wine can vary widely, and without specialized equipment, there’s no way to tell for sure how much SO2 you started with, or how much you’ve removed.
Will H2O2 Change the Taste of My Wine?
While the idea of removing sulfites this way may appeal to some—and consuming small amounts of H2O2 is perfectly safe—there are several potential complications that sulfite-savvy wine lovers should consider.
First, H2O2 doesn’t taste very good, and adding even small amounts may significantly impact the aroma and flavor of your wine.
Beyond the potential to taste the H2O2, Dr. Waterhouse says that removing sulfites is also likely to cause your wine to take on an oxidized aroma. Sulfites naturally bind oxidation products, including acetaldehyde, that are produced during fermentation. These molecules have an oxidized aroma, but when SO2 binds them, they become non-volatile, so they can’t be smelled. If you remove all the sulfur from your wine, those compounds will become volatile and contribute to an oxidized aroma, which probably won’t be desirable.
Free vs. Bound Sulfites
Finally, the chemistry behind the oxidation of sulfites is complicated. Even though H2O2 will at least temporarily remove some sulfites, it’s probably not as simple as adding a few drops of H2O2 and magicking them away for good.
Sulfur species exist in multiple forms in wine. Those forms can broadly be classified as “free” and “bound” SO2. When people talk about sulfites and sulfur sensitivity, they’re typically referring to free SO2, which is the SO2 that can be oxidized by H2O2.
Free and bound sulfur compounds exist in equilibrium, which means that if you remove some of the free sulfites by adding H2O2, eventually, some of the bound SO2 will likely be converted into free SO2 to re-establish that equilibrium.
Effectively, this means that to completely eliminate sulfur compounds from your glass, you’d probably have to add much more than the few drops typically recommended by the companies that manufacture these products. And that amount of H2O2 will almost certainly result in a glass of vino that nobody wants to drink.
As always, consult your healthcare provider about incorporating wine into a healthy lifestyle.—Kenny Martin
