Q: Can you taste white wine polyphenols, and are they associated with health benefits?—Xavier, Santa Cruz, Calif.
A: Our last two Health Q&As have focused on the taste of red wine polyphenols, such as quercetin and resveratrol, and tannins. What about white wine polyphenols?
White wines contain significantly lower levels of polyphenols than red wines. Most grape phenolics are found in the skins, seeds and stems. Since white wines typically have minimal contact with those parts of the grape, fewer polyphenols make their way into the wine. (Skin-contact whites and orange wines are notable exceptions.)
White wines made with pre-fermentation maceration or significant skin contact will have a higher overall phenolic content; a gentler or rougher pressing will also impact total phenolics. Phenolics can contribute to a wine’s perceived viscosity, and some white wines (especially those aged in oak barrels, which add their own tannins) may have light tannic grip, though that’s fairly rare. Thanks to their potent antioxidant activity, phenolics also interact with key aroma compounds in many white wines—in some cases protecting them from degradation (a boon) and in others rendering them odorless (a winemaking nightmare).
White wine’s phenolic compounds can be divided into two types: non-flavonoids and flavonoids. Non-flavonoids make up the majority of white wine’s phenolic content, mostly as a class of acids called hydroxycinnamates. These small molecules are found in grape juice and pulp, and they contribute to browning as white wine ages. But generally, they don’t seem to have much taste.
Dr. Andrew Waterhouse, emeritus professor of viticulture and enology at the University of California at Davis, told Wine Spectator that in past studies, “There didn’t seem to be any bitterness or astringency associated with [hydroxycinnamates], not in the levels found in wine.” Relatively few studies on wine and health have focused on non-flavonoids, though a hydroxycinnamate called caffeic acid has been linked to potential cardiovascular benefits.
Flavonoids are also present in white wines, though at significantly lower concentrations than in red wines. Certain flavanols, particularly catechins and epicatechins—which are found in grape seeds and can be responsible for bitterness in some red wines—contribute to what’s often called “phenolic bitterness” in some white wines. This taste sensation is a typical (and even desirable) characteristic of aromatic whites, such as Gewürztraminer, Viognier and Roussanne. It’s sometimes compared to the bitterness of almond skin or grapefruit pith and is often most noticeable on a wine’s finish.
But does that bitter taste indicate anything about a white wine’s potential health benefits? Many studies have linked flavanols to improved health. That said, research looking specifically at catechins and epicatechins is limited, so their particular health effects aren’t clear. Though it’s possible that a wine with significant phenolic bitterness may contain more total polyphenols—and thus greater potential health benefits—than one without, more studies are needed.
While the taste of a white wine isn’t necessarily an indicator of its phenolic content or its health benefits, scientists are increasingly interested in white wine polyphenols and their potential role in health. Though red wines contain many more polyphenols overall, when it comes to certain polyphenols (including protocatechuic acid, which has been linked to increased bone mineral density in women), white wine appears to have a leg up.
Though we have a general sense of how various polyphenols impact the taste of wine, our understanding of how they are digested and behave in the body continues to evolve. As always, talk to your healthcare provider about incorporating wine into a healthy lifestyle.—Kenny Martin
