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Components of Wine— and How to Begin Tasting Them

a glass of wine sitting on top of a wooden table


So what exactly is in that glass of wine?


Simple answer: water and ethanol make up approximately 98% of what’s in your glass. Let’s begin there.


The Big Picture


Ethanol is one of many types of alcohol (from a chemistry angle) which includes methanol (wood alcohol) and isopropyl alcohol (rubbing alcohol). Is it also the only kind of alcohol not toxic to humans up to a point. Toxicity is determined by dosage: small amounts of ethanol are not harmful and are mood-altering (mostly in a good way, as us wine drinkers can attest)  but overdosing (otherwise known as alcohol poisoning) is life threatening . 


It’s easy to know how much alcohol is in your wine as the US government requires it on every alcoholic beverage label sold in the United States, including wine (from those made with grapes to rice to fruit wines), beer, spirits, and kombucha. For example, the wine on my counter, a 2017 Chateau Musar Hochar from Lebanon, Oregon, is 13.5 % alcohol by volume or ABV (Grape-wise, it’s a nice blend of Cinsault, Grenache, and Cabernet Sauvignon). The ABV percentage can vary from 9-16% for wines, down to a few % for kombucha and light beer. Fortified wines like port or sherry, to which distilled spirits are added, can be up to 25% ABV, while spirits like vodka, whisky and gin can be up to 50% ABV. For distilled spirits, the protocol is to label the “proof,” which is double the percent alcohol (ie: 80 proof vodka = 40% ABV).


Water provides the bulk of the balance in your glass, so 98% minus 13.5% ABV, for example equals 84.5% water. This water (typically 80-90% of the bottle) must come from the juice extracted from the grapes. Adding water is considered cheating with very few exceptions, such as diluting the alcohol content below 15% to allow import into Europe.(1)


The Little Picture


For dry wines, or those with no detectable sweetness, the fun comes from the ~ 2% of the wine left after you subtract the water and ethanol. As you know, neither water nor pure ethanol has much flavor. Sugar is the third component in wine, which can range from 0% to 10% or more of the bottle. Most dry wines have less than 2% residual sugar, which is not sweet enough for the human tongue to detect (anything below 2% is undetectable to us).  But even those traces of undetectable sugar add crucial balance to a quality dry wine. The quality of the wine depends on the right ratio of alcohol, sugar, acid, tannins, and other fascinating minor components like anthocyanins, flavonols, esters, aldehydes, and resveratrol. These components we often credit for the wonderful taste but the magic happens in our olfactory sense, our nose.


For sweet wines the residual sugar percentage is higher and the alcohol percentage is lower since the yeast bugs convert sugar to alcohol during fermentation. If the winemaker wants a dry wine, they allow the yeast to convert all the sugar. For a sweet wine, the winemaker stops fermentation early to allow for sugar to remain so the alcohol percentage is lower as a result. 


While the alcohol is clearly labeled, sugar is not, so you must look for clues, or know what is typical for a certain wine style. Most red wines are dry, so maybe lean towards those if you don’t like sweet. Sparkling wines can range from dry (brut) to super sweet (doux) while whites can be all over the map: Chardonnay, Sauvignon Blanc, Pinot Gris (or Grigio in Italy) are typically dry white wines while Riesling, Gewurztraminer, can be either dry or sweet and Sauternes from France are always sweet. Check the label for key words like dry, brut, off dry (i.e. a little sweet), an RS percent (residual sugar) if there is one listed, or ask your wine merchant or apps for more information before you buy so you know what to expect.


But first and foremost, forget about expectations. Drink what you like, not what other people (wine snobs) tell you to like!


Wine Tasting 101


Our tongue can only detect sweet, salt, acid, bitter, and umami. If you’re just beginning, take out those sensations (and hot which is a sensation from high alcohol content) and all the other wine terms that may intimidate you. 

When you’re sipping your next wine, try this simple method to get the most out of your glass. Swirl your wine in a nice big glass and stick your nose in the glass, inhale deeply, close your eyes and see what comes up. The first step is to come from your nose. What detectable smells come forward? Think floral (rose, lilac) or fruity (citrus, strawberry, cherry,apricot); woody (tobacco, cedar) or spicy (black pepper, cinnamon). 

Sounds like a fragrance, right? If you hold your nose (or have lost your sense of smell from COVID) you can’t “taste” the wine anymore, but really, you can’t smell it. How do you identify these subtle aromas? It takes practice. But remember, everyone is practicing, even the “experts”. We are all just striving to get better! Take notes in a wine journal so you can keep a record of what you like and why.


Minor components for the chemistry geeks:

Acid is the 4th critical taste component, though at 0.5-0.75% is a small contributor in the form of tartaric, malic, citric, acetic and lactic acids. Acid creates a balance to offset sweetness, bitterness and alcohol and when added correctly, creates magic in a glass.


Phenolics are a family of molecules that are present in small amounts in wine but have a major impact on flavor and color. Anthocyanins contribute to color in red wines. Flavonols do the same in white wines. Tannins are the bitter compounds that create structure of full bodied red wines and help preserve wines as they age. Resveratrol, an antioxidant, present in skins and seeds of red grapes, has been linked to anti-aging, disease prevention and cancer. Go red wine!


Carbon Dioxide or CO2 is present in the bubbles in sparkling wine, either introduced externally for less expensive options, or created naturally via second fermentation that happens in the bottle for methode champenoise styles (French Champagne is the gold standard for this method).


Sulfites are often present in minute quantities as a by-product of fermentation, though they are often also added as a preservative to prevent wine from spoiling. Wines must be labeled as containing sulfites if over 10 ppm (parts per million). If no sulfites are added, the winemaker must use alternative methods for preservation, a very active area for natural and biodynamic wines. 


These details are fascinating to geeks like me but no one is going to test you, unless you want them to. But I do believe remembering a few of these nuggets will help you become a more discerning wine enthusiast and guide you towards refining your palate. The end game here is to find more wines to love and share, and taking a wine tour with Triangle Wine Country is an excellent start or continuation of your journey!


Book your tour with us today through the website. Regardless of your skill level, we’ll give you all the info you need to enjoy your next glass of wine.


Next Time: The not so good, the bad and the ugly: wine faults and how to identify them, plus: how to store your wines.




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