Sniff, Swirl, Sip – A Note on the Chemistry in Your Wine Glass

Hello Everyone! You have probably seen people swirling their wine glass and then sticking their nose far in the glass to smell the wine. For those of you who have seen the movie “Sideways,” you probably laugh at the scene when Miles is teaching Jack how to smell wine and then begins to describe all the aromas he is picking up from the wine…strawberries, passion fruit, asparagus, and a hint of nutty cheese. Why all the fuss? And as Jack says “When do we get to drink it?”

Actually, there is quite a bit going on in your wine glass and without getting too technical, we hope to help you understand it. This also might help you select a set of wine glasses and detect when you have a bad bottle or glass of wine. More times than you might think, we’ve popped open a bottle of wine, settled in to enjoy, and then … yech. The bottle goes down the drain because it was either a bad bottle or had become too oxidized, or had some other fault. We’ve even taken bad bottles back to our local store, which in one case caused the store owner to pull all of that lot off his shelves because he discovered the whole lot had spoiled. See, you’re doing everyone a favor by being able to identify when a wine is bad, versus just not your style.

The Technical Stuff:

The wine that you are holding in your glass is about 95% water and alcohol, and it generally breaks down something like 82% water and 13% alcohol. The remaining 5% consists of thousands of chemicals called phenols, esters, ketones, and acetates which are largely responsible for the flavors and aromas that Miles describes in the scene from Sideways.

Overall, in your glass there is a dynamic balance that is being achieved:

Sweet Taste (sugars + alcohol) <= = = = > Acids + Tannins (phenols)

Wine is acidic and white wines are generally slightly more acidic than red wines. The alcohol, phenols, and acids are reacting with each other to form esters and water, and the reaction is in balance going back and forth. The phenols that are reacting here are called flavanoids and the resulting esters are the components that provide many of the aromas and flavors in wine. In college chemistry class, we had a lab where we made banana oil and mint oil from some standard alcohols and acids; your wine is doing a similar lab but with many more chemicals. This back and forth reaction is why your wine tastes different from the first sip to the last sip an hour later. At the same time oxygen is factoring into this and is slowly consuming and changing the tannins.

The acids in wine consist of tartaric acid, lactic acid, citric acid, and malic acid along with a few others. You may have already heard the term malolactic fermentation associated with Chardonnay, which consists of turning the tart malic acid into lactic acid to make the wine taste softer. The winemaker often adjusts the wine’s natural acidity to balance with the sweetness and bitterness.

Tannins are the non-flavanoid phenols that are another critical component in wine, especially red wine. The tannins in wine come from the grape’s skins, seeds, and stems, and are extracted when the grapes are crushed. A winemaker can control the tannins to some extent by destemming the grapes prior to the crush, or by very gently pressing the grapes so as not to crush the seed, or the pip. There is more tannin in red wines than white wines. The existence of tannin makes a wine taste astringent, which is that dry taste you can get in your mouth after you taste a tannic red wine and it also helps preserve the wine while in the bottle. If it tastes more bitter than dry then the wine is out of balance.

However, sometimes when a red wine has absorbed too much oxygen, the wine tends to have a brownish color and will begin to taste oxidized and maybe a bit stale. When you go to a wine bar or restaurant and order a glass of red wine, it’s a good idea to check the bottle that your glass is coming from. If the bottle has been opened for a day or more and has been corked, it is likely that it will taste a bit staler than it should due to oxidation and loss of tannins. In this case, there is nothing wrong with asking for a fresh glass; you never want the bottom of a bottle especially if it has been opened a day or two before. We have quite often asked for a fresh glass if we see we’re getting the bottom of the bottle, and usually the bartender is more than happy to do this for you.

The Hardware:

Some wine glassmakers claim that the construction of their glasses can enhance the flavor of wine by stimulating some of the reactions we just talked about. The shape and size of a glass does help. You want it big enough to swirl and open up the aromas by helping the reactions along, and if it is shaped right, placing the wine in the right part of your mouth and tongue. So yes, the size and shape of the glass helps and that’s why most people like a larger glass for red wines. Some other glassware manufacturers claim that they have made modifications to increase the surface area along the glass to enhance your tasting experience. We’re not completely sold on these claims, but it always helps enhance your wine enjoyment if you have a decent set of glasses.

So, get yourself some decent sized wine glasses, give the wine a sniff, swirl and enjoy the chemistry in your glass with each sip.

Like what you drink, drink what you like!

Rachel and Bryan Gavini