The world’s most complex beverage happens to be mostly water. The remainder is predominantly alcohol, and the leftover sliver defines the bottle. While that may seem underwhelming, it’s precisely what makes wine so complex you could spend a lifetime getting to know it. I’ve found learning more about those components will help you enjoy and appreciate wine more.
If you can, grab a bottle of wine and take a sip as we talk about each component. Whether or not you can articulate what you’re experiencing, your reaction to the wine is largely determined by the following components. For this exercise, a red wine is better, so you can experience tannins.
Water
Wine is 85% water. Its polarity acts as the backbone for the rest of the components to interact in a manner we find pleasant. Water also has a high specific heat, which comes in handy when you’re sipping on a cold glass of rosé on a warm day.
Alcohol(s)
Alcohol might be the reason viticulture exists. Fermentation is the process of yeasts consuming sugars and turning them into ethanol and carbon dioxide. Most dry wines fall between 10.5% and 15.9% alcohol. The alcohol level in a bottle of wine is inversely proportional to the amount of residual sugar in it. While ethanol is the primary alcohol, other alcohols are created as well, which add aromas and complexity.
In addition to animating conversation with your companions, alcohol keeps the wine protected from microbes and adds body and flavor. Indirectly, many of wine’s flavors are by-products of fermentation, so without alcohol, wine would never be much more interesting than the flavor of grapes.
High alcohol wines tend to have more body and more ripe fruit flavors. If that’s your jam (get it?), look for wines with over 14% ABV. If you prefer more subdued fruit (meaning you know it’s there, but it’s not the most dominant characteristic), you may want to look for more moderate levels of alcohol, around 12.5%. Similarly, if you don’t enjoy full-bodied wines, high alcohol wines will not be for you.
If you want to get better at detecting alcohol levels without looking at the bottle, the best way to experience it is through observing heat in the back of your throat. Take a sip of wine. After you swallow, take a short inhale (half a breath). If you feel a lot of heat in the back of your throat, the wine has high alcohol. If there’s just a gentle bit of heat, it’s likely medium alcohol. The nice part about learning to gauge alcohol levels is you have immediate confirmation by looking at the bottle. Unlike aromas and flavors, alcohol levels are easily measured in a lab. One thing to keep in mind: most countries allow for a 50 basis point difference (meaning 0.5%) between the actual alcohol level and what the label says. If you find yourself constantly thinking 14%, but the label says 13.5%, you might be right.
The alcohol level in a wine is also important when pairing wines with food. High alcohol wines are always full-bodied and can wash out lighter foods. For instance, a Central Coast Zinfandel will dominate a light piece of whitefish, making both fish and wine taste worse — the opposite of our goal with wine pairing. Not only reds, but full-bodied white wines can be too overpowering as well. Alcohol also creates a drying sensation as it evaporates, so it’s best to avoid spicy foods with high alcohol wines.
Tannins
Tannins are polyphenols that exist in many food products including chocolate, coffee, and tea. In nature, they help protect plants from overzealous herbivores as well as pathogens. When we consume tannins, they bind with proteins in saliva, creating the feeling of astringency (the proteins are what help saliva lubricate your mouth). When tannins are either unripe or too plentiful, this sensation is off-putting (and thus a deterrent to a hungry animal). Depending on the amount, length, type, and shape of the tannins, we may feel anything from a soft velvety coating inside our mouths to a drying sensation like we sucked on a piece of gauze. We often use words ranging from green, chalky, or grippy, to ripe, supple, smooth, or fine to describe tannins.
Red wines are most well-known for their tannins, but orange wines have them too. White wine and rosé can have them, but generally in low amounts that don’t have a major impact on our experience of the wine.
Tannins in wine come mostly from grape skins, but also seeds, stems, and to a much lesser extent, oak. It turns out tannins are complex little things and scientists are constantly learning more about how they function and evolve in the wine. Tannins polymerize (connect with each other and grow longer), but they also change shape and structure in ways we don’t yet understand fully. Aged wines are less astringent, and often smoother. Anthocyanins, the phenols that give red wine its color, also bind with tannin, which is part of the reason some red wines turn to brown as they age.
Each of us has our own sensitivity to tannins. Some people are drawn to very tannic wines, others find them too overpowering, unless accompanied by specific types of food (e.g., a rare steak). Not only the level of tannin, but the type of tannin can help you find more wines you like. If you have access to a good wine shop, telling the person working there about a wine you liked the tannin structure of can help them find something else you like.
Tannins are important for food pairing as well. The combination of a big Cabernet Sauvignon with a rare steak is a classic for good reason. Tannins act as an astringent, drying out your mouth, which enhances the perception of the steak’s juiciness, making it seem more delicious. You generally want to pair high tannin wine with something juicy. A well-done steak will not serve the same purpose. Fattier steaks are more delicious with high-tannin wines, as the tannin helps cut the fat. A ribeye will serve you better than filet mignon. Who am I kidding, besides in a Beef Rossini, when is a ribeye not better than filet mignon?
Acidity
When we consume something acidic, our mouths release saliva to protect our teeth. The saliva cleans out our mouths, which feels refreshing. Acidity is also one of the major components that allows wine to age, which is especially important for white wines. While there are many types of acids in grapes the two most common are tartaric and malic acids. Tartaric acid is critical to wine. Malic acid, however, can be harsh on our palates and is sometimes converted into lactic acid through a process called Malolactic Fermentation.* (It’s also known as ‘Malo’ or sometimes MLF).
While pH isn’t a perfect measure of a wine’s acidity, it is the most common and easy to understand. Because pH is an inverse logarithmic scale, lower pH indicates higher acidity. Most wines fall between a pH of 3.0 and 4.0. Acidity is generally higher in white wines. Part of the reason acidity tends to be higher in white wines is that potassium in grape skins neutralizes some tartaric acid during red winemaking. Almost all red wines also undergo MLF, softening their acidity further, while most whites either skip it entirely or use it selectively. High acidity also enhances our perception of tannin and reduces our perception of residual sugar, meaning too much acidity in a red wine may make the tannins unapproachable, while high acidity in a white dessert wine keeps the wine from being cloying.
Understanding acidity in wine can help you find more varietals you like. For instance, if you had a Premier Cru Chablis and loved it, you might also enjoy other high-acid varietals, such as Riesling and Chenin Blanc. Acidity is also crucial with food pairing. High acidity can help cut fat and restore our palates. For instance, Nebbiolo (high acid, high tannin red grape) is an excellent partner to lamb. Sauternes is a classic partner to foie gras (in this case, both for its acidity and residual sugar). One of my favorite surprise pairings was at Californios in San Francisco, where they paired a Meursault (full-bodied white Burgundy) with Wagyu. It was absolutely mind-blowing!
Carbohydrates (Don’t worry, there aren’t many!)
Most wines are produced in a dry style, meaning the majority, if not all, sugar is fermented into alcohol. Wines that are marketed “low carb wine” are really taking advantage of a fact inherent to dry wine. Don’t fall for it, you’re probably spending more money per bottle for the same or lower quality wine. Lower end wines such as the typical White Zinfandel might have more residual sugar, as will great wines such as some Rieslings, Champagne, Chenin Blanc, and of course, sweet wines.
That being said, when a wine does have residual sugar (often abbreviated RS), the sugar adds complexity to the wine. It can help round out high levels of acidity, such as in German Rieslings, and it also adds viscosity to the wine, making it feel a bit heavier in your mouth and adding body. Quality wines made with residual sugar are often excellent accompaniments to a variety of foods, including fatty foods and spicy dishes.
Terpenes, Esters, and Thiols, oh my!
These tiny things comprise the smallest percentage by volume of wine (about 0.5% of volume), but create the most differentiation between wines. They comprise the aroma and flavor compounds that make wine what it is and a bottle of wine unique. There are more than 9,000 molecules that impact the flavor of wine, but we’ll stick to the major groupings here.
Esters are often credited with lots of flavor contribution, but the reality is they tend to be short-lived and mainly impact youthful, fruit-driven styles of wine. In fact, while fruit esters contribute pleasant aromas to youthful wines, they become soapy with time as the carbon chain increases in size.
Thiols, also known as mercaptans, are responsible for both attractive and repugnant aromas in wine. Some mercaptans add various fruit aromas, e.g., black currant, passionfruit, and grapefruit. Others lead to notes of reduction in the wine, such as garlic, cabbage, or rotten eggs. Our olfactory senses are extremely sensitive to thiols and are detectable in miniscule quantities: about 10 parts per billion. Thiols are quite complex, both in their formation during fermentation and their preservation during winemaking, but are not yet fully understood.
Terpenes give us some defining aromas: rose, lychee, lavender, and eucalyptus. While winemakers can integrate various practices to enhance or diminish the presence of terpenes, their basic characteristics are strongly correlated to their varietal. For example, rose and lychee notes are telltale signs of Gewürztraminer in a blind-tasting.
Aromatic compounds are what drive what we love about wine. Being able to recognize various aromas and flavors in wine will help you find more wines with similar profiles. The opposite is also true, you may find what you want to avoid in wines. For instance, I find methoxypyrazines (green pepper) off-putting in red wines, so I avoid cool climate/cool vintage Cabernet Sauvignon.
The best part about understanding these components is that your next glass is already better. Notice the heat at the back of your throat, the way your mouth waters, the grip on your gums, and how long the flavor lingers after you swallow. The wine has been talking all along. Now you know a little more of the language.
*Technically, Malolactic Fermentation is a misnomer. Malolactic conversion is more accurate, but fermentation is the more common phrase.