Have you noticed that wine writers describe wine aromas as smelling like just about anything other than grapes? It’s a funny thing. Why the heck should the wine smell like plums when it’s made of grapes? *The UC Davis Wine Aroma Wheel includes dozens of descriptors, but no matter how hard you look at it, you won’t find grapes mentioned there. Doesn’t it feel like it’s almost an insult to describe the wine as grapey?

As you know, the plum, licorice or spice can’t be added unless it’s indicated on the label: “Plum-flavored wine.”

So, how does that stuff get in there? Sometimes, it's simply that the fragrance or flavor of the wine reminds us of tobacco or black olive. It's the best language we have to put across our impressions.

Plant science tells us that there are chemical cross-overs in the things you see growing outside your window. For instance, the tannin in wine comes primarily from the grape skins. But, there’s also tannin in tea leaves, which is why a strong cup of tea dries out your mouth. Cinnamon is also quite tannic. There’s wood tannin in oak, so we know that new barrels contribute tannin to the wine as it ages. If tea leaves, oak and Cabernet have tannin in common, why can't they have flavor compounds in common too?

So, the message is that there can be something of a grape in a plum and something of a plum in some grapes.

Plum image via Shutterstock
Sometimes there’s a good degree of certainty about the source of specific characteristics. For instance, the grassy, herbaceous character of Sauvignon Blanc can be chalked up to detectable levels of a compound called methoxy-pyrazine. It’s also found in asparagus, beets, bell peppers and other vegetables. Like TCA (cork taint), we’re very sensitive to it and can detect it at parts per trillion. It turns up, but to a lesser degree, in Merlot (cool-climate Merlot often reminds me of beets) and Cabernet Sauvignon. The pyrazine is more noticeable in cool-climate wines than in warm, which might explain why the Europeans are quite accepting of herbaceous character while California producers are terrified of it, especially in their reds.

Beside contributing tannin, new barrels impart a wide range of aromas, from fresh coconut to coffee. More on that in another piece.

Often, the source is uncertain. For instance, smoky character could be grape or barrel derived. Syrah is somewhat smoky by nature, but dark barrels also impart a smoky scent. Spice can come from the grape (Zinfandel) or the barrel, or who knows where.

Many of the characteristics, especially those derived from fermentation and aging, are not well understood. Some enologists believe that we mistakenly identify sulfur compounds as “terroir” flavors, or mineral characteristics, when they may actually be the result of fermentations with nutrient deficiencies.

There’s no point in pretending that the delicate mix of mysterious elements that come together to influence aroma and flavor are fully understood. The things that are known are just puzzle pieces. Part of wine’s charm is its ability to confound. It’s part of the fun, don’t you think?

*The aroma wheel does include methyl anthranilate, which is the compound that makes grape candy taste so very grapey. Wines made from native American grape varieties, such as Concord, are often described as “foxy,” which is code language for Welch’s Grape Juice character - methyl anthranilate.