Why you should care

A “tongue” of golden nanoparticles might hold the secret to tastier wine. 

If you’ve ever sipped red wine, you’ve probably noticed a sandpaper-y sensation that makes you squint your eyes and pucker your lips — aka “astringency” in wino-speak. Winemakers taste their own wine or enlist the help of professional tasters to ensure it has just the right astringency levels. But soon, an electronic “tongue” might make their job a little easier.

Scientists have developed a nanosensor — a device that detects molecular interactions at tiny, nanoscale levels — that they say mimics how our tongues experience astringency. The device could allow wineries to monitor and adjust levels throughout the winemaking process rather than rely on error-prone human taste at the end. Duncan Steward Sutherland, an associate professor at the Interdisciplinary Nanoscience Center at Aarhus University in Denmark, who led the nanosensor research, predicts that winemakers can get their hands on one in as little as three years.

Here’s how it works. Red wine is swimming with compounds called phenols, which is found in grape skins and seeds. They bind to proteins in saliva, causing them to change shape and clump together into globs of spit, leaving the inner surfaces of your mouth dry and coarse. The device — a thin plate covered in gold nanoparticles, roughly the size of a laptop — mimics that process. The researchers first coated the plate with a salivary protein, then poured on the wine.

We’ve got something showing what happens in your mouth.

Duncan Steward Sutherland, Aarhus University

An instrument called a spectrometer measures the amount of red light the nanoparticles absorb, which indicates how many phenols are stuck to them. The more red they absorb, the more astringent the wine. But phenols also destroy salivary proteins when they bind to them, causing those viscous globs of spit to form whenever you drink red wine. So the spectrometer also measures the damage to salivary proteins based on how light passes through them.

Today, Sutherland and his colleagues — including scientists from the University of Porto and the Porto Superior Institute of Engineering in Portugal — are working with two companies to develop the nanosensor. Similar nanosensors measure only the amount of phenols present. “We’ve got something showing what happens in your mouth,” Sutherland said.

But it might be too soon to say, said Andrew Waterhouse, a wine chemist at University of California, Davis. “Astringency is a response in humans,” he said. “They need to get measurements from people, and they can compare that to their device” to confirm whether it actually detects astringency as people do. Plus, Waterhouse adds, it looks at a type of phenol that’s “not very abundant in wine.”

Sutherland notes that the device might also be used to detect Alzheimer’s disease and other conditions stemming from structural changes in certain proteins. Despite the kinks left to work out, the idea of a technology that makes wine tastier and diagnoses disease is still a sweet one.

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