We’ve covered sugar, fruit, and acidity, and have two last wine components in my three-week, wine-basics tutorial. Sure, there’s still some summer left to enjoy, but for now let’s replace those swim caps with thinking caps and dive into alcohol and tannin!
While most of what we know about alcohol we learned outside of the classroom, in all seriousness, alcohol serves an important purpose in wine’s overall balance (and, at times, our own).
Alcohol (specifically ethanol) is the main product of the yeast fermentation of natural grape sugars. The sugar level, or brix, in the grapes when picked determines the final alcohol content of the wine. Measured as a percentage of total volume, typical alcohol volumes range from 8 to 14 percent. Wines with 8 to 11 percent alcohol typically come from cooler climates, where grapes struggle to ripen and contain fewer sugars to convert into alcohol. Wines with an alcohol content below 8 percent indicate a wine with residual sugar, meaning that fermentation stopped before all its sugars were converted into alcohol. Wines with 14 to 16 percent alcohol come from very warm climates that produce very ripe grapes. Yeasts stop functioning at 16 percent alcohol, so wines in the 17 to 22 percent range are, by definition, fortified. These include sherry, port, madeira, marsala and vermouth.
Inebriation isn’t the only thing you’ll notice as the alcohol percentage increases. In dry wines, alcohol contributes to the body or weight of the wine in your mouth, also termed “mouth feel.” Low-alcohol wines have a light body with a mouth feel of skim milk. High-alcohol wines have a full body with a mouth feel of whole milk or cream, encouraging wine writers to use wonderful descriptors like dense, unctuous, chewy and fat. In sweet wines, residual sugar will give a wine body even if the alcohol levels are low.
If you’ve ever witnessed someone swirl a wine and then admire its “legs,” she is noticing rivulets on the sides of the glass that relate to the surface tension differences between water and alcohol. The more alcoholic the wine, the slower the legs travel and the more defined they are. So, leggier isn’t better—just higher octane.
Wine’s alcohol is felt as warmth in the back of your throat. If a wine burns like a shot of Patrón, then it is considered out of balance or “hot” in wine speak. So, unless you’re tasting wine with Paris Hilton, it’s not a compliment.
One last component to discuss before we’re all verifiable wine experts: tannin. More of a sensation than a taste, tannin is the astringency you feel on the roof of your mouth that—as a winebar customer so delicately described—“sucks all of the saliva out of your mouth.” Coming from the pips (grape seeds), skins and stalks, tannins are organic compounds most often found in red wines because of the juice’s skin contact. Small amounts can also come from the oak barrels used to store wines. Tannins act as a natural preservative for a wine intended to age, giving it structure and “backbone.” They fade with age, giving the wine’s fruit a chance to gain complexity. Wines made from grapes with thick skins (like Cabernet Sauvignon) will often be overly tannic and “grippy” in their youth. Time in the cellar is the only remedy, unless you like drinking turpentine. Food, especially fats, will quell unruly tannins, so save your first-growth Bordeaux or California Cabernet for a night when steak’s for dinner.