Smoke Gets in Your Wine – An Answer to a Serious Problem

Alright, wine lovers and makers, pull up a chair, uncork a bottle (hopefully untainted.), and let’s chat about something that’s been putting a real cork in the joyous world of winemaking: smoke.

You’ve probably noticed that our planet is getting a bit… toasty. Warmer temperatures and drier conditions mean more wildfires and bushfires, and these fiery fiascos aren’t just a threat to homes and habitats. They’re drifting right into our vineyards, especially those beautiful ones in places like California’s Napa and Sonoma. Remember 2020 when some harvests just had to be canceled because of smoke damage? It was a real heartbreaker.

When Smoke Lingers, Taint Happens

When wildfire smoke decides to hang out in a vineyard for a while, it can leave a not-so-charming souvenir: smoke taint. Think undesirable smoky, burnt, and ashy aromas and flavors in your otherwise perfect Pinot. It’s like inviting a campfire to your sophisticated dinner party, and it just… doesn’t fit. The tricky part is that whether this unwelcome guest shows up depends on a bunch of factors, like how long the smoke hung around and how thick it was.

Enter the brilliant Dr. Kerry Wilkinson, Professor of Oenology at The University of Adelaide. She’s basically a smoke-taint detective, searching for clues (or “markers”) to help winemakers identify smoke-affected grapes before they invest all that time and money into making wine that might end up tasting like an ashtray.

The Double Trouble of Volatile Phenols

“There are compounds (volatile phenols) found in the smoke,” Dr. Wilkinson explains. “The current hypothesis is that these compounds are taken up into grape bunches, diffusing through the skins, and because these compounds can be a bit reactive, the grapevine responds by adding one or more sugar molecules onto the compounds to lower their reactivity.”

And this, my friends, is where it gets a little complicated. You see, these smoke compounds come in two forms: a “free form” and a “sugar-bound form” (aka glycoconjugates). And detecting them both is like needing two different keys to open one door. You’d typically need Gas Chromatography-Mass Spectrometry (GC-MS) for the free forms and Liquid Chromatography-Mass Spectrometry (LC-MS) for the sugar-bound ones. While some big wineries might have one of these fancy machines, very few have both. This means sending samples out for testing, which is both expensive and, crucially, slow.

The Time-Sensitive Taint Test

Dr. Wilkinson and her Ph.D. student, Colleen Szeto, did some fascinating research, recently published in Molecules, that uncovered another layer of complexity. They found that winemakers might be underestimating their smoke taint risk depending on when they collect their grape samples after smoke exposure.

Imagine this: one hour after smoke exposure, you can detect those volatile phenols. But just 24 hours later, poof. They’ve largely vanished, metabolized by the grapevines. Meanwhile, the sugar-bound forms start to appear a day after exposure and then really ramp up between one week and one month. This means there’s a pretty narrow, time-sensitive window to accurately predict smoke taint with current lab methods. Missing that window could mean a nasty surprise down the line.

A New Hope for Winemakers: The HORIBA Aqualog

This is where the story gets exciting. Szeto and Wilkinson are on a mission to develop a simpler, faster, and less expensive optical method to spot smoke-affected grapes and wines. Their secret weapon? The HORIBA Aqualog®.

This clever machine uses something called A-TEEM™ spectroscopy, which simultaneously measures absorbance, transmittance, and fluorescence excitation-emission matrices. Think of it as giving the grape (or wine) sample a super-speedy, multi-dimensional optical “fingerprint.” The best part? Minimal sample prep, lightning-fast acquisition (we’re talking minutes for a broad scan), and significantly lower analysis costs compared to those traditional GC-MS or LC-MS methods.

As Dr. Wilkinson puts it, “What we’re interested in with the Aqualog, is development of a rapid method so we can screen grapes and say, ‘You don’t need to worry about smoke taint, you’re well below problematic levels; or, you’re far into problematic territory, so there’s no point picking; or you’re in this middle window, and you should go ahead with more detailed chemical analyses to better inform your decision-making.'”

Imagine the relief for winemakers. Instead of waiting weeks for expensive lab results, they could get a quick read on their grapes right after a smoke event. This allows them to make timely decisions during the frantic vintage season, saving time, money, and a lot of headaches.

The team has already seen promising results, correlating Aqualog’s fluorescence fingerprints with key smoke taint markers in red, white, and rosé wines. Their next step? Applying this to grape samples. Because, as Dr. Wilkinson wisely notes, “It’s good to be able to classify wines correctly using the Aqualog, but ultimately the wine industry can already do that by tasting the wine… So really we want to be able to scan grape homogenate or grape juice and make decisions at that point.”

So, here’s to a future where winemakers can breathe a little easier, armed with quick, reliable data to protect their precious product from the dreaded smoke taint. Cheers to science making our sips sweeter.

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