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In the summer of 2008, smoke taint became a problem in California. It has been a problem for years in Australia, which has provided a rich source of knowledge and research on the topic. The below is from a combination of our own independent research, research conducted by various Australia authorities and institutions, UCDavis, and our own experience.
It has been established that lignins in burning wood break down into small phenols which are then taken up by grapevines and other plants. Unfortunately, smoke taint character is derived from a whole host of these small phenols, and the smoke taint character, a matrix effect, differs dramatically from that of barrel aging and toasted oak.
Smoke tainted wine has flavors and aromas that are variously described as wet ashtray, charred meat, burnt coffee, beetroot, salami, smoked salmon, or bacon. It also is often described as producing a drying, ashy backpalate in wines. This is more readily noticeable in white wines, but young red wines should be carefully screened for this, because it can be mistaken for young tannins, but does not resolve with aging.
When is the risk?
Most people fear smoke the most when the grapes are nearly ripe. There is risk at this time, but the greatest risk appears to be during midsummer, prior to and through the end of veraison. During this time the vines are actively storing and/or translocating compounds to the grapes. It takes little smoke in the vineyard at this time to taint the grapes. The fire does not need to be nearby to impart this taint.
What should I NOT do?
- don't drop or reject the grapes--it is not the growers fault
- don't send the wine off as distilling material
- don't wash the grapes--the taint is in the skin of the grapes not ash or residue on the grapes
- Don't cut short skin contact unless you want to make a Rose. Nearly all of the taint compounds are extracted in the first 2-3 days of fermentation
- and definitely DON'T carbon, isinglass, or pvpp fine wine or juice.
This last item bears explaining. The taint compounds are glycosidically bound in unfermented juice (red or white) and require some enzymatic activity to hydrolyse and express themselves. Being glycosidically bound protects them from carbon. So, you will strip out much of the desirable character of your wine, and none of the undesirable character if you use carbon on your juice. Using carbon on your wine may reduce the smoke character . . . and just about every other flavor too. For more about fining, see below.
Guaiacol and 4-Methylguaiacol
Guaiacol and 4-methylguaiacol do not seem to participate much, if at all, in smoke taint (they are merely the best markers we have). At the date of this writing, nobody has been able to adequately characterize the compounds involved in the sensory expression, nor their relationship with each other. It is widely agreed that there is some number of aromatic phenols involved in a matrix relationship which result in the sensory expression. Therefore, the presence of guaiacol and 4-methylguaiacol, and their relative levels are reliable markers for smoke taint, and the relative intensity.
The problem with these markers is that analysis of guaiacol and 4 methylguaiacol is not a good indicator of the status of a processed wine, or of a wine that has been in contact with oak, whether barrels, chips, etc. For more on this, see Our Process below.
Our Process
Alternative Treatments
Preparing for Harvest
Does Smoke Taint Return After Processing?
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