Q: Do tannins have a taste, and are they associated with health benefits?—Pearl, Zurich
A: In our last Health Q&A, we discussed how many of red wine’s potentially healthy polyphenols, such as the stilbene resveratrol and the flavonol quercetin, have a bitter taste. However, most people likely won’t notice any bitterness from these polyphenols since they’re present in wine at such low concentrations.
But there’s another class of polyphenol found in significant amounts in red wines: tannins. Tannins are found in nuts, tea and many other plants. They’re also found in grape skins, seeds and stems, as well as in the oak barrels used to age some wines. There are many kinds of tannins, in a range of shapes and sizes, and they are one of the key factors that determine a wine’s ability to age gracefully.
Generally speaking, tannins aren’t something you taste—they’re something you feel. Dr. Andrew Waterhouse, emeritus professor of viticulture and enology at the University of California at Davis, told Wine Spectator, “There is no taste bud that detects astringency.” Rather, tannins are sensed via “a physical sensation in the mouth.”
Tannins are responsible for the drying sensation of many red wines (and some white, rosé and orange wines, though tannins are present in those wines in much smaller amounts). By binding with glycoproteins in saliva and causing them to precipitate, tannins reduce the mouth’s natural lubrication. People often describe this effect as grip on the sides of the mouth or traction on the tongue. Tannins are key components of a wine’s mouthfeel and texture, which in turn significantly affect the overall impression the wine makes on the palate. Tannin is also an important consideration when pairing wine with food, since it plays well with fatty foods such as cheese and red meat.
Some research has indicated that the polyphenol quercetin could modify the perception of tannin. Specifically, says Waterhouse, quercetin seems to “[soften] the astringency of tannin.” He also says that while red wine pigments, particularly anthocyanins, don’t appear to have sensory characteristics of their own, they’re important in modifying the perception of tannin, especially as a wine ages.
Some researchers believe that young, highly concentrated, tannic reds are most likely to confer health benefits. This may be due to these wines’ relatively high levels of procyanidins, a type of tannin, which studies have linked to cardioprotective effects. While the verdict is still out, and researchers are increasingly interested in the health properties of other wines (including white wines), people hoping to maximize the potential health benefits of their wine intake may wish to seek out younger, tannic reds.
Though tannins mostly impact a wine’s texture, wines with a lot of tannin can taste bitter to some people. That may be due to elevated concentrations of seed tannins, which are smaller than other grape tannins and consist mostly of short chains of the flavanols catechin and epicatechin. Depending on several factors such as phenolic ripeness, length of maceration and other aspects of winemaking, these seed tannins can stick out in a wine, leading to bitter flavors. It’s also possible that other types of tannin do have bitter flavors, or that they exacerbate the perception of bitter flavors caused by other molecules in wine, but this isn’t clearly understood. As Waterhouse says, “It’s messy because tannin itself is this mixture of hundreds of different things, and then those each react in different ways with different things. So you get this very, very complicated mixture.”
Catechin and epicatechin are also involved in phenolic bitterness, a common and often desirable taste perception in some white wines. Watch out for our next Health Q&A, on white wines, to learn more about how phenolics impact their taste and potential health effects. And as always, talk to your healthcare provider about incorporating wine, tannic or not, into a healthy lifestyle.—Kenny Martin
