That wine label you’re struggling to decipher—likely in the tiniest of print and often relegated to an edge—is a useful bit of information. It’s the ABV, or alcohol by volume.
In theory, it’s a simple number that tells how much alcohol is in the wine. But in truth, it tells you so much more.
A wine’s ABV can be as low as 5 or 6 percent or as high as 20 percent. And just where it falls determines, to a surprising degree, the character and quality of what’s in the bottle.
Winemaking isn’t really a very complicated process. Ripe grapes are crushed or pressed to release their juice. Yeasts rush in to feast on the sugar-rich brew. The byproducts of this microscopic feeding frenzy are alcohol and carbon dioxide. The CO2 dissipates harmlessly into the atmosphere, the alcohol remains behind and, hey, you’ve got wine.
The alcohol content of the sort of red, white and pink wines we drink with meals typically ranges between 12 and 15 percent. Readings in this range imply that the fermentation was complete and, as a result, there will be no sugar left behind to be perceived as sweetness. It’s dry wine. Readings much below this suggest the opposite—some sugars were not fermented and the wine will exhibit some sweetness.
Alcohol and sweetness, then, have an inverse relationship: The higher the former, the lower the latter, and vice versa.
Armed with this information, you can generally guess where on the axis of sweet to bone-dry a wine falls. Checking the ABV can be a big help when choosing a bottle to accompany a dish. Alcohol levels are also useful for deciding if a wine is right for the season or occasion.
Higher alcohol content generally means the wine is proportionately robust. A garden party in July is a good time for something with a low or very moderate ABV. A winter night spent with a pot of short ribs is a good time for something a bit more boozy.
We might ask why certain wines are sweet and others dry. In some cases, the outcome is completely natural. Super-ripe grapes can contain such potent loads of sugar that the resulting alcohol kills off the yeasts before they can complete the job they have started. Winemakers use other techniques to achieve the same results, making wines both potent and luciously sweet.
It’s worth noting that alcohol’s role in wine isn’t just to leave us feeling warm and lightheaded. Alcohol is also important in preserving wine as it ages, in creating texture and mouthfeel, and in providing ballast for both fruit and tannins.