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The Role of SO₂ in Winemaking
Sulfites in wine are one of the most talked about, and misunderstood, parts of winemaking. You’ve probably seen bottles labeled “sulfite-free” or heard someone claim they’re the cause of headaches. The truth is much more nuanced.
Sulfur dioxide (SO₂) is one of the most important tools in a winemaker’s kit. It’s both an antioxidant and antimicrobial, helping wines stay fresh, preventing spoilage, and protecting them during sensitive stages like fermentation and bottling. When used thoughtfully, SO₂ preserves a wine’s character so what you taste is a true reflection of the vineyard and vintage.
Balance is key: too little SO₂ and the wine risks instability; too much and it can overwhelm the wine with off-putting aromas (think burnt matchstick). Like barrels or fermentation techniques, it’s simply a tool, applied where and when it’s needed.
Sulfites Beyond Wine
Wine may get most of the attention, but sulfites are widely used in foods for the same reason: to protect freshness. Dried fruits, condiments, packaged goods, and even salad bars often contain more sulfites than wine. In fact, the FDA notes that dried fruit or trail mix can contain several times more sulfites than a glass of wine.
Do Sulfites Cause Headaches?
This is one of the most persistent myths in wine. According to the FDA, fewer than 1% of people are truly sensitive to sulfites, and their reactions are typically respiratory (such as asthma symptoms), not headaches.
So what causes the so-called “wine headache”? The culprit is usually something else:
- Histamines and tannins, especially in red wines
- Alcohol itself, which can dehydrate the body and dilate blood vessels
- Lifestyle factors, like drinking without food or water
In short: sulfites are not the likely cause of headaches, despite their reputation.
The Bottom Line
Sulfites are not the villain they’re often made out to be. They’re a protective tool that ensures wines reach you in their best form. Used wisely, SO₂ helps preserve freshness, prevent spoilage, and highlight the character of the vineyard and vintage. At McKahn Wines, we take a thoughtful approach to every step of the process. Learn more about our Commitment to Sustainability and how it shapes our winemaking decisions.