We’ve all done it.
In a winery tasting room or fine-dining restaurant, at a crowded party or simply relaxing at home, we’ve all held up our glass to the light and asked, “What’s in this wine?” Besides the alcohol, that is.
Well, for starters, there are long chains of organic compounds. They’re the result of chemical reactions during the winemaking process and give the wine in your glass its fruity and floral aroma. If a wine is made “dry,” that means the yeast munch up almost all of the available sugar in the fruit and convert it to alcohol (and carbon dioxide). Any residual sugar makes your wine semi-dry or various levels of sweet. Acid in a wine balances sweetness and gives wine its liveliness. Think about what lemon or vinegar does for food.
Red grape varieties – Merlot, Malbec, or Cabernet Sauvignon, for example – are fermented on their skins. That’s what gives these wines their pigment. The skins, seeds, and stems of grapes also lend tannins to the wine and cause your mouth to feel astringent or “grippy.” Aging red wine tends to smooth out tannins and to make them silky instead.
Are you with me so far?
Now for that controversial additive present in most wines: sulfur dioxide (SO2). The use of SO2 in wine production has been going on for centuries. It’s used throughout the winemaking process to prevent browning and spoilage. Without SO2, it would be difficult to transport wine or age it for long periods of time. When used in excess, though, SO2 can produce a pungent, and definitely distasteful, struck-match aroma. Most would consider this aroma a fault.
Here are the questions I hear about SO2:
- I get headaches from drinking red wine? Is it the sulfur?
Probably not. Sulfur allergies are rare. Tannins are most likely the cause. Do dark chocolate and strong black tea affect you the same way? They’re both strong in tannins, too. What to do? Try low-tannin red varieties, such as Barbera, Beaujolais, or Grenache. Better yet, stick to white wine.
- Can wine be made without adding SO2?
Yes, sort of. Grapes may arrive at the winery already treated with SO2 in the field. However, this would only add a trace amount to your wine. A careful winemaker can limit the amount of SO2 used at critical control points – after pressing and before fermentation, after fermentation and first racking, during storage and when bottling – but few go without using SO2 entirely, because it’s just too risky (see #1). That said, if you’re really intent on finding wines with little-to-no SO2, it’s possible.
I’m not hyper-concerned about SO2. Instead, I look for evidence of care and artfulness in producing wine. Aroma, taste, balance – these are the qualities I seek.