At its core, wine is composed of water, alcohol, aromatic compounds, acids, and tannins. All of these individual elements add something unique to that glass of vino you're enjoying. So let's break it down:
Wines start with grapes, some even end with grapes, since the yeast needed to convert the grapes' sugar to alcohol is frequently found on the skin of each berry. White grapes make white wines. But "white grapes" are usually green or yellow in hue, and some are even pink or red. Extremely few grapes actually have red flesh, so the color of the grape refers to the skin on the grape. White wines can even be made from red grapes, as well as Rosé and red wine.
There are several varieties of grapes as well. Those that make some of the more popular white wines include Albariño, Chenin Blanc, Chardonnay, Pinot Gris (or Pinot Grigio), Pinot Blanc, Sauvignon Blanc and Viognier. The more popular red wine grapes are Cabernet Franc, Cabernet Sauvignon, Grenache, Merlot, Pinot Noir, Sangiovese, Syrah (or Shiraz) and Zinfandel. Many lovely rosés are made with blends but some of the more dominant grapes for rosé include Pinot Noir and Zinfandel.
The yeast cells turn delicious, sweet grape juice into wine. They eat sugar and produce alcohol as a by-product. Many vineyards like to use indigenous yeasts—those found on the grape skins themselves—as each vintage can bring a different combination of yeast strains, which may allow for more distinctive and complex wines. Most wineries, though, use cultivated, or commercial yeasts.
There is a distinction, however: As some wineries find that a specific yeast that was indigenous to their vines produced a better than average result, the winery may begin to cultivate the yeast. Most wineries that use truly commercial yeasts use them because they are efficient and tolerant of high-alcohol environments (aka the Achilles' heel of many indigenous yeasts; it can lead to what are known as stuck, or incomplete fermentations.)
Acid is the part of wine that makes you smack your lips and leaves your mouth watering. It’s a vital component of deliciousness in wine. Acid is naturally occurring in all fruit, and we know from making lemonade that there is a subjectively ideal balance that can be achieved between sweetness and acidity. Even in a dry wine there are flavors that we can perceive as sweet (alcohol also can give an impression of sweetness), so having the right amount of acid in a wine is crucial.
Grapes are born with primarily hard Malic and Tartaric acids, though many whites and most reds go through a secondary, bacterial fermentation (as opposed to yeast-driven) that converts the acid of green apples (Malic acid) to the softer acid of fermented dairy products such as yogurt (lactic acid). As grapes ripen, sugars increase and acids tend to decrease, so some winemakers routinely add additional acid to their wines. The most common acids used in acidification are Tartaric acid, Malic acid and citric acid. Some wines are also de-acidified by adding specific salts that can cancel out tartaric acids.
Because of the differences in grapes and winemaking, some wines tend to be more acidic than others. Examples of higher acidic wines include many sparkling wines, Sauvignon Blanc, dry Riesling and Chianti.
Tannins come from the seeds and skins of grapes -- and stems, too if they’re added while the wine is still fermenting—as well as from wooden barrels that can be used to age wines. The tannin in wines acts as a preservative and, along with acidity, is referred to as the structure of a wine. Tannins make your mouth pucker, your gums feel fuzzy, and your mouth feel dry.
You can probably see already that having the right balance between drying tannins and mouthwatering acids is pretty important. Tannins can also be added to wines in powder form. Of course, some wines display a high level of tannins—usually red wines, such as Cabernet Sauvignon, Syrah and Nebbiolo as well as the red wines from Bordeaux and red wines from Tuscany, Italy, known Super Tuscans.
In modern winemaking, additives have become a common part of the wine recipe. Some additives have long historical roots, others are more recent additions to the winemaker's list of ingredients, all of which can be used to “improve” wines. Here's a brief rundown of what else may have been added to your next glass of wine.
Enzymes are added to fermenting wine to help prevent the growth of bad yeasts that can cause wine spoilage. There are even enzymes that improve the formation of sediment in young wines, allowing for better filtering, and thus leading to higher yields. You can observe this kind of sediment in a wine like Beaujolais Nouveau.
Polysaccharides are added to promote the retention of color, tannin, and flavoring compounds extracted from grape skins.
Gum Arabic is added to wine to lock in the aromatic compounds in a wine, but it also adds richness, which has become its main propose.
Sulfur products are used as an anti-oxidative preservative in wine. These are products that have long histories in winemaking, and are actually one of the wine additives that we’re seeing less, not more, of as winemakers develop a better understanding of what a sufficient dose of SO2 is.
Wine ingredients like these are listed on the wine labels.
6. Fining Agents
Once upon a time wines were fined (think of it as filtering, but with the filtering drifting down through the wine as opposed to the wine being forced through a physical filter) with ox blood and egg whites. (Learn more about the ancient history of wine in our series on early winemaking practices.)
While egg albumin is still a common fining agent, it has been joined by things like bentonite clay, gelatin, and even silica. There is no actual residue left from proper fining, so don’t look for chunks in your glass.
For more wine news and reviews from Gregory Dal Piaz, visit Snooth.com.