Why wine 'smoke taint' concerns could be a thing of the past

A wine grower in Tasmania's Huon Valley says he has found a way to remove smoke from tainted grapes and not lose a vintage.

In January last year, Hartzview Vineyard in Gardner's Bay experienced heavy bushfire smoke, which rose and spread throughout the property, which sits 250 metres above sea level.

Owner Bob Patterson said it was an unusual sight.

"The smoke was very intense and lingered up here for several days," Mr Patterson said.

"It was a good two to three months before we would pick our grapes. We tried to remain optimistic and hoped the smoke [on the grapes] would be washed away in future rains."

Smoke taint in grapes

About six weeks before picking, their optimism took a turn as sample results from a local wine testing facility revealed high levels of smoke taint in the grapes.

"We had to make the decision whether to pick or not, and also ask ourselves if we had the desire to do something about the smoke," Mr Patterson said.

"We've been making table wines like pinot here for over 30 years and making fortified wines for about the same.

He decided to pick the grapes and experiment with the knowledge he'd retained in wine-making and distillation.

Instead of letting the pinot noir skins soak and ferment to bring on colour and flavour, he decided to remove the skins.

"We were producing, essentially, a rose table wine that was still very tainted," he said.

"From my limited experience with distillation I learnt that stills don't like sulphur, so the normal protection that you use to keep the wine sound with sulphur wasn't an option.

"We then thought about fortifying."

To fortify wine is to strengthen it, and the process usually results in a higher alcohol content.

"We used this technique to fortify the table wine, which means going up to 18 per cent per volume in alcohol. That kept it very stable without using chemicals," Mr Patterson said.

That gave him time to apply a range of suggestions he received from the Australian Wine Research Institute in Adelaide and overseas viticulturalists — along with help from Vintessential Laboratories, a wine testing facility in Hobart.

"There are two steps with distilling brandy: The first step is called the stripping run where you remove all the methanol from the fruit, the nasty bits.

"You then precede to a stripping run where you have your fores, feints and hearts, the good bits. The hearts then go in the barrels for ageing."

Smoke taint analysis

Vintessential Laboratories Tasmania manager Annie Baldwin oversaw Mr Patterson's smoke taint analysis.

"What Bob is doing is really interesting. If you do go ahead and ferment your wine, it gives you an option to make something that is drinkable," Ms Baldwin said.

"When the smoke enters the grape it either will exist as a free form or bound form that binds to sugar and compounds in the grape.

"During fermentation the bound form can be released into the wine once the sugar molecules are broken down — basically they're distilling the smoke taint compound out of the solution."

Three different lab results over a six-month period found Mr Patterson's bound numbers reduced from 160 to basically undetectable — the wine is now smoke-free and looking good for quality brandy.

Future research

Ms Baldwin said a lot more research needed to be done to better understand how smoke affected different fruits.

"Last year we started collecting a lot of grapes that weren't exposed to smoke. They are all different varieties and have different levels of the compound," she said.

"This has allowed us to create some baseline data."

Mr Patterson will soon have his brandy ready for final testing.

"We will send that back to the lab and get results on what level of brandy we've achieved," he said.

"If it [smoke] happened again and small producers are getting worried, please think of a second alternative so your work during the year is not wasted."