There are quite a few wine faults and at some point you can add a new one to all the existing ones. At least since 2008 there is a new wine fault making its way into the wines: smoke taint.

It is however limited at the moment, to those countries and places who have to deal with serious issues of fire. Australia and California are unfortunately amongst them. The smoke of the fire (wildfire, bushfire, etc.) penetrates into the skin (but it might also transferred by the leaf to the fruit) causing the major problem, it’s a sort of contamination as especially making red wine you have to work with the skin to release the colour.

Dennis Patton wine maker of the Golden Vineyards was pointing this issue out to me. In 2008 heavy wildfires caused damage in California and the thick smoke lasted for weeks, the mainly affected area was Mendocino County within California. He also said a lot of people are not entirely aware of the problem.

It is not entirely new to the world, smoke taint. Wine makers in Australia have to deal with the situation now since a few years and did a lot of research on the problem but it is yet not fully understood.

The main components which create the smoke taint are: guaiacol, 4-methylguaiacol these two are the “smoky guys” but in addition there are some others to be found: eugenol, furfural, 4-ethyl guaiacol, 4-ethylphenol. Later two are also in wines with noticeable character of brettanomyces (brett). The guaiacol threshold levels are usually low 5-25 parts/billion (ug/l), this makes it higher then TCA and H2S but still lower then 4-EP and 4-EG responsible for brett.

There is something interesting as well, that while guaiacol and 4-methylguaiacol are the major smoke delivering and “tainting” compounds they are found also in wines which are aged in oak barrels. Hence in wine which was in touch with wood that got burned with fire (releasing smoke) to make the barrel according to the toasting level. Certainly all comes down to threshold levels and while making the barrel with fire and having the byproduct smoke only for a short time, the wildfires and their smoke is for a longer period and actually affects the grapes in the first place.

The compounds of guaiacol, 4-methylguaiacol gives the smoky char like aromas with a meaty spice. And it’s formed during the toasting, increasing with toasting levels.  But other compounds like eugenol a volatile phenol and furfural which is produced while carbohydrates break down thanks to heat during the toasting process. Usually described as caramel, almond or even butterscotch.

The main descriptors when describing smoke taint in the grape or in the wine are: smoky, ash, dirty, burnt or some would even use, salami barbeque and smoke salmon attributes to point out the problem. Now, I had a chance to taste two Californian smoke tainted wines, see my “tasting note” on them at the very end and they are nothing like wine in toasted barrels (barrique).
While really the smoke is the major problem during the fires which causes the problem in this case some researches points out that guiaiacol one of the compounds related to smoke taint is water soluble and could absorbed by the roots after rainfall or irrigation and then transported into the berries. Smoke is airborne and composed of water vapor, ash, carbon, tar and other fragments and gases which some of them are highly toxic as well.

The grapes are most vulnerable to the smoke taint shortly after veraison, but they are exposed all until the harvest if smoke reaches them. The smoke taint compounds are mainly in the tissue layers of the skin. Dennis was pointing out tasting the grape (chew the skin) and the wine (fermentation enhances the volatile phenols) itself is a very vital task. The possibility is given that some people are not entirely aware of the problem and smoke tainted wines will be released later the year to the market.

While said hand harvest is more gentle then machine and the free run juice has less smoke taint then the press wine because it’s mainly in the skins there is no such thing as smoke-neutralizing agent or pretending aeration (e.g. racking, last option decanting) would simply blow the “smoke” out of the wine. This was clearly not the case with the two smoke tainted wines which we tasted. Dennis was saying he trusts only one solution: reverse osmosis. This can help while fining agents remain questionable you might only reduce it but not eliminate it says Dennis with whole milk, egg white fining or carbon filter. Reverse osmosis is the best way to handle the issue. Some people pointed also to spinning cone beside the by Dennis mentioned reverse osmosis.

The majority of the smoke taint compounds are not in free form but rather bonded to sugars this makes is somewhat difficult to analysis them sometimes. Some research points out the enzyme hydrolysis as a solution but this could affect the result of the measurement once done later with gas chromatography.
The best method to analysis smoke taint compounds guaiacol, 4-methylguaiacol is said to be by: gas chromatography – mass spectrometry, GC-MS Headspace analysis.

Tasted wines smoke tainted wines (no label, Pinot noir, 2008)

29/07/09
Sample 1
Dennis says immediately “It smells like Frank Sinatra’s ashtray”. Pale colour, burned with a reductive fruit character on the nose. The palate enhances this burned, sparkle feeling and there is virtually no fruit existing.

Sample 2
Disjointed and a ash like character on the palate, rather smoky then burned. But very empty finish and short.

Tags: smoke taint

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