All the flavors in wine come from the grapes and the winemaking process. Your senses aren’t lying to you when you stick your nose in a glass of Pinor Noir and smell cherries, or when you nose a Cabernet Sauvignon from Napa and get a big whiff of vanilla. Wine has many of the natural chemical compounds found in fruit and spices. Here are some of the most notable, grouped by the sense with which you’ll notice the chemical most.
Smell
Smell is the most important sense in wine tasting because scent directly impacts taste. Other than salty, sweet, bitter, sour, and umami, what you perceive as flavors are actually aromas. The following chemicals affect smell, but you’ll also notice them when you sip wine.
Some of the most notable compounds in wine are methoxypyrazines, which are compounds found in both grapes and wine. They’re most commonly found in Bordeaux varieties like Merlot, Cabernet Sauvignon, Cabernet Franc, and Sauvignon Blanc. In these wines, methoxypyrazines come off as tomato stems or green bell peppers. Two others, isopropyl-methoxypyrazine and sec-butyl-methoxypyrazine, are also present, albeit at lower levels. They add, respectively, notes of asparagus and earth.
Not all chemical compounds smell so pleasant. Some can throw off a wine entirely, like those present when the wine is exposed to brettanomyces yeast. Brettanomyces, or brett, can add 4-ethylphenol, which smells like Band-Aids. It can also add 4-ethylguaiacol, which smells like clove and bacon.
Another “off” aroma that can occur when you’re smelling and tasting wine comes from sulfur compounds. But it’s not just cut-and-dry sulfur. Some sulfides smell like rotten eggs and sewage, such as hydrogen sulfide and methyl thioacetate. Then there are sulfides that smell like rubber, including methanethiol (which also has rotten cabbage notes), carbon disulfide (which the Australian Wine Research Institute describes as “chokingly repulsive”), diethyl sulfide (also brings in some garlic notes), and ethanethiol.
And that’s not all. There’s the onion-smelling sulfide, diethyl disulfide; the cabbage sulfide, dimethyl disulfide; and the one that smells like canned corn and asparagus, dimethyl sulfide.
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