The Grape Identity Crisis and How Spectroscopy Separated History’s Most Confusing Cultivars

In the humid, disease-prone vineyards of the American Midwest, a botanical cold case has lingered for more than a century and a half. It revolves around a rugged, cold-hardy vine that produces tight clusters of dark, ink-black berries. To the naked eye, a vine growing in Missouri looks identical to one planted in Arkansas. For decades, nurseries, growers, and even the federal government have treated them as the exact same plant.

Historically, however, a quiet faction of winemakers insisted there were two distinct cultivars at play: Norton and Cynthiana.

The prevailing theory was simple rebranding. Norton cuttings, originally cultivated in Virginia in the 1820s, migrated west to the Ohio River Valley and Arkansas, picking up the local moniker "Cynthiana" along the way. During the mid-1800’s even the world’s most elite ampelographers—botanists who specialize in identifying grapevines by the shape of their leaves and tendrils—struggled to find a single morphological difference between the two.

It turns out the experts were looking in the wrong place. To find the truth, they didn't need to look at the leaves and tendrils. They needed to look at the light bouncing off the wine.

Thanks to a unique collaboration between university researchers and the advanced optical engineering capabilities of HORIBA, the mystery has finally been cracked. And the solution is poised to reshape the wine industry across 47 states.

The effort to untangle this viticultural knot is spearheaded by two men: Dean Volenberg, Ph.D., a viticulture expert at the University of Missouri, and Stephan Sommer, Ph.D., with the University of Tennessee, a seasoned enologist.

Their mission was born out of a desperate need for agricultural conservation.

"There is not a Cynthiana cultivar deposited in foundation plant services to preserve its genetics through time, and it's not available historically to growers," Volenberg explains. Because the vines were deemed identical, nurseries spent decades selling mixed bundles of cuttings. A grower might order Cynthiana and receive Norton, or a hybridized mix of both, completely unaware of the difference.

To prove the cultivars were distinct, Volenberg and Sommer had to eliminate every possible environmental variable. They secured a vineyard block in Augusta, Missouri, that is planted with historically sourced Norton and Cynthiana vines right next to each other.

"They have the same environmental conditions, so it's pretty hard to argue that the wines are growing in different environments," Volenberg says.

When the grapes ripened, Sommer took over. He brought the harvest into the winery and treated both batches with scientific rigidity—using the exact same yeast strains, the same maceration tools, and identical winemaking procedures.

The results in the glass were immediate.

"What we've seen is that the historical records are correct," Sommer notes. 19th-century texts had hinted that Cynthiana lacked the harsh, aggressive tannin structure of Norton and was ready to drink far sooner. "They were different every vintage. All the four vintages we have at this point, the wines were significantly different."

The sensory differences were undeniable. Volenberg points out that young Norton wines—those less than a year old—often carry a distinct, vegetal astringency that requires a couple of years of barrel aging to mellow out.

Volenberg said. "You take a young Cynthiana on the same token: no vegetal notes. Fruit forward, ready to drink right away."

But subjective tasting notes, no matter how consistent, aren't enough to convince the scientific community or force the Alcohol and Tobacco Tax and Trade Bureau (TTB) to rewrite its labeling laws. The team needed hard, empirical data.

Traditionally, proving a botanical difference requires DNA testing. But whole genome sequencing is a massive, agonizingly slow, and cost-prohibitive hurdle.

"(DNA testing) is very expensive and time-consuming," Volenberg says. Between DNA extraction, library construction, and post-sequencing bioinformatics, the costs are staggering. You're looking at anywhere from $1,200 a sample up to over $3,000, just to do the sequencing of a single accession."

For an industry that relies on rapid testing to make harvest and blending decisions, genetics was a dead end. They needed a faster way to prove what they were tasting.

The turning point happened thousands of miles away from the Missouri vineyards, at the Unified Wine & Grape Symposium in California. There, Sommer crossed paths with Adam Gilmore, Ph.D., an application scientist with HORIBA.

Gilmore proposed a radical, non-destructive solution: fluorescence spectroscopy.

Rather than tearing apart the DNA of the vines, Gilmore suggested using light to map the chemical soul of the finished wine and create a molecular fingerprint. He utilized HORIBA’s Veloci Wine Analyzer—an advanced spectrometer that has become vital to the science and study of wine and winemaking.

The Veloci works by firing specific wavelengths of light through a wine sample and measuring the light that bounces back. Different molecular compounds—specifically anthocyanins and phenolics—absorb and emit light differently. The resulting data creates a highly specific, three-dimensional topographic map of the wine’s chemical composition.

“Having the fluorescence spectrometry is much, much cheaper than going through whole genome sequencing,” Volenberg said.

Gilmore ran Sommer’s Missouri samples through the Veloci, focusing on the visible excitation range related to anthocyanin composition. The instrument did what the human eye and traditional ampelography could not. Using Principal Component Analysis (PCA), the Veloci easily separated the Norton and Cynthiana samples into completely distinct chemical clusters.

"We had similar results also with the phenolic range, but I think it was a little easier to distinguish; the statistics were higher, with the anthocyanin composition region," Gilmore explains.

It was the revelation the researchers needed.

Fluorescence spectroscopy provided an objective, affordable, and nearly instantaneous method to authenticate the wines.

The implications of this discovery stretch far beyond a few rows of vines in Augusta.

For the American wine industry—specifically the 47 states outside of the dominant West Coast growing regions—disease-resistant hybrids are the lifeblood of the business.

"On a wet year in Missouri, we're going to spray Norton maybe three, maybe top four times for disease or fungus," Volenberg points out. By contrast, a white hybrid like Vignoles might require 22 or 23 sprays in the same season.

By officially resurrecting Cynthiana as a distinct, recognized cultivar, growers gain access to a grape that shares Norton’s legendary cold-hardiness and disease resistance, but yields a more approachable, fruit-forward wine that doesn't require years of expensive barrel aging before it hits the market.

"It allows them a little bit more creative freedom with their wine marketing, with their labeling," Sommer says. "For wineries, they will always have to tell a story about their wines... this whole 'Norton and Cynthiana used to be the same, now they're different'—we can develop a story around that that helps sell more wines."

Currently, the TTB still treats the two names as synonymous. But with HORIBA's spectroscopic data providing the empirical backbone, the groundwork is laid for an industry petition to officially separate them.

For Volenberg, Sommer, and Gilmore, the success of the Veloci Wine Analyzer opens the door to an entirely new frontier of wine authentication. The team is already looking ahead, hoping to build a comprehensive spectral database that can trace not just cultivars, but individual clones, subtle regional terroirs, and even detect counterfeit blends.

After 150 years of confusion, the debate is finally settled. The vines might look nearly identical, but the truth is in the glass, and light provides the evidence.