An Old-School Technique Finds Modern Winemaking Fans

By WineBottleMag
February 13, 2025
Fans Finds Modern OldSchool Technique Winemaking
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It’s the year 2025 and winemakers have a full suite of technology at their fingertips that can help analyze, assist and predict every step of the winemaking process. Optical machines can sort grapes, machines can regulate tank temperatures and acidity. Computers can measure other details that dictate a wine’s doneness in seconds.

Certainly, technology has its upsides. But in contrast, some winemakers are leaning into the analog. They’re unpacking their beakers and test tubes and measuring malic, lactic and tartaric levels through paper chromatography, a process similar to how film is developed.

“It’s an extremely old-school process,” says Ryan Alfaro, the winemaker at Alfaro Family Farms and Farm Cottage Wines in the Santa Cruz Mountains. “I learned this from my dad.”

Justin Phillips, the assistant winemaker of Rosewood Winery and Meadery in Niagara, Canada, learned it in winemaking school, but still employs it in the winery.

It isn’t a commitment to tradition or a love of ephemera drawing both him and Alfaro to the process. Paper chromatography, it turns out, is a speedy, reliable and affordable way to test acid levels in a wine undergoing second fermentation.

And if it ain’t broken, why fix it?

What Is Paper Chromatography?

Essentially, paper chromatography is “a really quick, efficient analytic test for winemaking,” says Phillips. “All it really requires is a special type of filter paper, a solvent and a jar. It gives us a sense of, ‘Okay, we’re on the way.’”

The process starts by winemakers gathering samples from every barrel. The still-fermenting product (either wine, must or juice) is dotted onto a piece of chromatography paper.

“On the paper, you put different acid standards—lactic, malic and tartaric acid standards,” explains Phillips. The paper is placed in a jar of solvent (similar to the solvent used for film development) and then hung up to dry.

There are many acids present throughout a wine’s lifespan. Malic acid is one of the most common organic acids found in grapes, but the hyper-tart substance is best known for its role in malolactic fermentation. The process follows malic acid as it’s converted into soft, creamier lactic acid (the same acid found in milk, and that gives many California Chardonnays their controversial butteriness).

There’s also tartaric acid, which helps control the acidity of a finished wine (and the finished wine’s pH level).

As the page dries, the solvent will evaporate, leaving streaks of yellow, red and green across the blue paper. The level of contrast and the color of each sample will indicate how much malic, lactic and tartaric acid are left in the wine and the farther the colors travel on the paper, the further through its transformation the wine is.

Squiggles of malic acid on the page? It means your Chardonnay is still lean and mean. As those evaporate, the white wine gains all rich unctuousness.

Image Courtesy of Alfaro Family Vineyard

Why Use Paper Chromatography?

For Alfaro, using paper chromatography is a no-brainer: it’s quick, easy and dependable. If you’re curious about how a wine is progressing, he says, simply pop open the barrel, extract some of the fermenting liquid and drip. You’ll have the answer in the morning.

“You can tell which barrels are actually going through secondary fermentation—whether it’s started or how long it’s going,” Alfaro says.

The cons? “I wouldn’t say paper chromatography is a lost art, but people aren’t as interested in doing it anymore because it’s very time consuming,” he says.

Alfaro and his father make a wide range of single-vineyard Chardonnay, Pinot Noir and Grüner Veltliner from across the Santa Cruz Mountains. That means their winery is full of barrels of this and that—a Bates Ranch Cabernet Sauvignon here, leathered but juicy Pinot Noirs from Corralitos there.

To test each barrel, Alfaro has to climb over each barrel one by one, dip in his pipette and go through the process. “You feel a bit like a mad scientist,” says Alfaro.

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But time is on his hands in January and February, when secondary fermentations take place. It’s a slow season for winery workers. What else do you have to do?

“There’s not really a lot going in those months—you can knock out hundreds of barrels in a day,” says Alfaro. “Spend a week doing that and you get a great baseline on where your wines are headed.”

Not that many winemakers do, it seems. “If people really loved winemaking, they’d spend that time climbing around their barrels over twiddling their thumbs in the office,” shrugs Alfaro.

A Cost-Effective Source of Information

Paper chromatography’s high-tech alternative would be to invest in a (pricey) machine to test the acids. If that’s not in the budget, the next best thing would be to collect a composite of all the barrels (testing every single barrel is expensive) and ship it (also costly) off to a lab. A day or two later, one would receive an update on how your wines are progressing.

With paper chromatography, however, all steps are handled in-house. “It saves you a ton of money,” says Alfaro. “It’s very cheap—the main cost is paper and little plastic pipettes.”

The process also helps winemakers keep tabs on wines during their most vulnerable state.

Rosewood Winery—which works with energetic Blaufränkisch, fresh and unfiltered Savignin and amphora-aged Riesling—prefers a light touch in the vineyard and winery. Its team works with indigenous yeast and minimal sulphur, which can be unpredictable if left unsupervised. So staff tests barrels and tanks frequently, monitoring how fermentations are evolving so they can course-correct when a barrel goes awry.

Checking in with paper chromatography also helps them decide when they should add sulphur to their tanks. If the year is cold and fermentation isn’t kickstarting, they have a decision to make.

“Is it worth it to leave our wines unprotected and unsulphured to see if it will go through malo?” says Phillips.

Their tests are conducted by harvest interns from Brock University and Niagara College, which both helps Rosewood tackle all their tanks and barrels and gives the students in-situ practice. The winery team makes decisions from there.

Of course, there’s the visual draws of the paper chromatography process. Each sheet is swirling with blue hues and gold—a portrait of a wine in progress.

“Sure, it’s not the most crucial step in the winemaking process,” says Alfaro. “But it’s giving you more information. And, it’s fun.”

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