Beyond Terroir: How the Chemistry of Wine Builds Flavor and TexturePhoto by Dan Meyers/Unsplash Drink Features wine chemistry
People can spend their entire careers teasing out the intricacies of a wine’s flavor. There’s so much to consider in a bottle of wine: the variety of the grape inside, where it was grown and what kind of weather and farming conditions shaped it, the manner in which that grape was fermented and aged.
Many would argue that ultimately, a wine’s aroma, flavor and character is most determined by terroir—a French term that means the complete natural environment in which a wine is produced, including soil, weather and topography. But underneath all of the magic and poetry of terroir is basic chemistry. If you hang around vintners for long enough—or geekily peruse enough tech sheets, basically the album liner notes of wines where winemakers break down the nitty gritty details of the wine—you’re going to hear and see terms like Brix, acidity, TA and Ph levels getting thrown around a lot.
Read on for insight into what these chemistry terms mean and how they affect the final flavor in your glass.
At its most basic, Brix is a scale used to measure the total dissolved compounds in grape juice. Which… sounds like it essentially tells us nothing, right?
“Brix is a way to measure sugar level within a grape,” explains Lori Budd, co-founder of Dracaena Wines in Paso Robles. “As the grape ripens, the sugar levels increase, which gives us a higher Brix reading. At the same time sugar levels are increasing, the acid level typically decreases.”
If a Brix level is too high and an acid level is too low, the wine becomes off-balance, she explains. This leads to high-alcohol, flabby wines.
But it’s not always that straightforward, says Annie Edgerton, a wine educator and sales associate at New York’s Flatiron Wines & Spirits.
“Brix levels don’t always translate seamlessly to what you taste in your glass,” Edgerton says. “Especially amid climate change, when grapes can reach the ‘appropriate’ level of Brix—the level needed so that yeast can ferment the sugars to the desired degree—the other elements necessary for a balanced wine may not have evolved at the same rate, leading to green or underripe flavors.”
Acidity (+ ph + TA)
Acidity is what it sounds like. It’s a general term used to describe that fresh and tart (occasionally sour) taste resulting from (ideally) naturally occurring organic acids present in the wine.
pH is a scale from 0 to 14 used to measure the concentration of acidity versus relative alkalinity. Generally, low-pH wines have a high concentration of acidity—most wines range between 2.9 and 4.2 pH. Wines with very low pHs are very tart, while wines with very high pHs are often described as flat or flabby.
Whites hit their sweet spot around 3 to 3.4, while reds are generally 3.3 to 3.6. But wait … there’s more: Total Acidity, a.k.a. TA.
“pH and TA are related but not the same thing,” says Karl Weichold, estate winemaker for the Stoller Wine Group, a collection of family-owned wine brands from Oregon’s Willamette Valley. “pH is the total amount of the molecule that makes solutions acidic, while TA is that solution’s ability to buffer against increases in pH. Since your mouth has a higher pH than wine, TA is considered the best measurement for understanding the perception of acid on the palate.”
Perception and Balance
Perception of flavor is as important as the building blocks that lead to that perception. For Eric Kramer, winemaker at Yamhill, Oregon’s WillaKenzie Estate, much of the impression a wine makes on your palate comes down to texture.
“To me, texture is one of the most important parts of the wine-drinking experience. I love wines that offer a great and balanced mouthfeel, and texture is a big part of this,” Kramer says. “If we’re speaking about dry wines, I would say Brix plays a pretty indirect role in texture. In other words, Brix is just a metric I’m monitoring to make a big decision—but it doesn’t necessarily drive texture.”
Decisions about when to pick based on Brix require a complex set of considerations, Kramer says.
“Let’s say I have been monitoring Brix accumulation in a parcel of grapes that was on the docket for harvesting,” he says. Is the Brix level increasing rapidly in the vineyard and at a pace that is ahead of tannin ripeness? Should I harvest the grapes because I am concerned grapes may be accumulating too much sugar and the resulting wine may be higher in alcohol?”
If a grape is 23 degrees Brix, it’ll finish below 14% alcohol, Kramer explains. If grapes are harvested above 24 degrees Brix, the finished wine will exceed that 14% point. But it is possible to have grapes without fully developed flavors and tannin at 23 degrees Brix, so Kramer says his picking decisions based on Brix are a judgment call.
“When I’m making that picking decision, I’m generally thinking most about how the tannin, flavor and acidity will fit into my wine’s style and expression,” he says.
Acidity and pH have an enormous influence on the texture and mouthfeel of a wine, says Edgerton.
“I like to say acidity is the amount of acid and pH influences the feel of that acid,” she says. “So you can have a high-acid wine with a bit higher pH and it won’t feel so jarringly tart in your mouth, or a lower-acid wine but with a bit lower pH and it will feel more pleasantly balanced.”
Academic discussions of wine are great, but sometimes the best way to fully comprehend the chemistry of wine is to put those theories to a taste test:
Cool climate wines: Cool climate wines tend to have lower Brix and alcohol levels and higher acidity levels. Kelsey Glasser, owner of the Willamette Valley restaurant and wine bar Arden, and the wine education platform Raise a Glass, recommends seeking out Mosel Valley Riesling, Alto Adige Pinot Grigio and Burgundian Chablis (made from Chardonnay) for archetypal examples of the phenomenon.
Warm climate wines: Warm climate wines tend to have higher brix and alcohol levels and lower acidity. Glasser recommends looking for Barossa Valley Shiraz, Napa Valley Cabernet Sauvignon and Mendoza Malbec for classic examples.
Sauvignon Blanc: You can taste “the paradigm of riper versus earlier chemistries (read: high brix/high pH/low acidity versus low brix/low pH/high acidity) in Sauvignon Blanc,” says Weichold. “In cooler climates like Marlborough in New Zealand, the leaner, more acid-driven styles are austere and lither on the palate; they play nicely with the cut herbs and gooseberry [tasting notes] so common from that region.” But Sauvignon Blanc grown in hotter parts of California or eastern Washington will show “less acidic focus, and riper flavors of stone fruit are emphasized on a boozier palate.”
Pinot Noir: This red beauty is another exemplar of the chemical paradigm at play. “The most familiar and apparent example of this difference would be Pinot Noirs made from the warmer sites in California’s northern coast versus those of the Willamette Valley,” Weichold says. “Those California wines tend to lose acidity during ripening and generally make broader wines with less focus on acidity and more of a focus on higher alcohols. The cooler climes of the Willamette Valley create wines balanced by a focus on acidity and restrained alcohol.”
In the end, terroir does help determine the chemistry of the grape, but a winemaker’s picking decisions based on that chemistry ultimately determine a wine’s style, flavor and texture.