This is part of a series called Wine Words, a glossary in the works that breaks down the barrier between those in the wine know and those who have no idea what the hell everyone's talking about. A new word posts once a week, covering everything from a grape name or region, to a winemaking or tasting term.
acidity (n.) tasting term
Acidity is one of the primary components of wine - and grape juice for that matter - which is why we almost always find a reference to it in tasting notes. Bright, crisp, fresh, refreshing, zing, nervy, sharp...these are words that describe a wine high in acid, though technically I think "bright" refers to color and clarity so I'm probably misusing it. For me, bright means the lights are turned up and my attention snapped to, which is kinda how I feel when the first sip of sauvignon blanc washes over my palate.
Acidity in wine effects color in red wine, flavors, ability to age, texture and, arguably, deliciousness. We detect acidity on the sides of our tongues where it makes us salivate, signaling to the stomach that it's time to eat, even if we just did.
A wine with low acidity comes across flat, bland or flabby, like an old lady's upper arms. A wine high in acidity will meet any of the aforementioned descriptors. A wine way-high in acidity might be described as an enamel scraper, as in it just dissolved the enamel off your front teeth.
There are several types of acid that make up the Total Acidity of a wine, which together make up the end result and impression of the wine. The two most discussed are malic acid and tartaric acid. Malic acid is prominent in apples, tartaric acid is responsible for the potassium bicarbonate known as Cream of Tartar. Sometimes tartaric acid will precipitate out after the wine has been bottled, usually as a result of being stored too cold, and will throw a clear sediment that looks like tiny shards of glass or magic crystals. These are totally harmless.
As grapes ripen, sugar levels go up and malic acid levels go down. Tartaric acid drops a tiny amount but mostly remains at the same level. Acid levels are one of the things winemakers look at when they take grape samples from the vineyard to the lab for analysis, which helps them decide when to harvest the fruit. If the sugars get too high and the malic acids drops too low, the resulting wine is marked for the nursing home before it even gets a chance to ferment.
According to David Bird's wine science book, "Understanding Wine Technology," a number of additional acids are produced during fermentation, including succunic, propionic, pyruvic, lycolic, fumaric, galacturonic, mucic and oxalic. I have never heard a single one of those acids mentioned in conversation, least of all when tasting wine. Though I find it interesting in a, whoa there's so much shit I don't know about making wine, kind of way.
After a wine finishes fermentation, it might go through malolactic conversion, where those sharp malic acids are converted to a softer lactic acid, as found in sour milk. Most red wines will go through malo as do full bodied whites, like round, buttery California chardonnays. How much Total Acidity is left at the end of fermentation says a lot about how long a wine will last in bottle. Like lemon juice, acidity is a natural preservative, though it will dissipate over time. So the more acidity a wine has to begin with, the longer it will last.
Most wines reviewed on Pig&Vine fall on the bright, crisp, tart end of the spectrum, because that's what I like to drink. High acidity, in both whites and reds, make me want to relax, have a bite to eat, and forget that I'm human and life is hard.