Smoke Taint
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Checking Grapes and Wines for “Smoke Taint”
Background
“Smoke Taint” in wines was first identified as a serious problem following the 2003 wildfires in Australia and British Columbia. Subsequent fires in Australia during 2006-07 caused additional losses in the millions of dollars. The California wildfires of 2008, with over 1,700 individual fires at their peak, caused smoke to cover most of Northern California during June and July.
ETS Laboratories developed an analytical tool to screen grapes, even though it was too early to know the extent of “smoke taint” problems from the 2008 California fires. This helped growers and winemakers identify potential problems and take immediate corrective actions whenever possible. In addition, ETS offered analysis of smoke taint markers in juice and wine.
Smoke Taint Markers
“Smoke taint” is caused by a wide range of volatile phenols. Phenols in smoke are absorbed on vines and grapes and end-up in finished wines where they can cause objectionable odors described as “burnt”, “smoked fish”, “salami”, “ash” and “ashtray”.
Guaiacol and 4-methylguaiacol have been identified as the primary indicators of smoke taint. Both appear to be present in all smoke damaged wines and their concentration in unoaked wines usually correlates to the degree of taint present.
Current Research
“Smoke Taint” research has been conducted primarily in Australia and is still in its early stages. Current research and observations suggest that the uptake of smoke compounds is greater immediately post-veraison. Vines do not need to be exposed to thick smoke to produce tainted wines. There is evidence suggesting that smoke taint compounds absorbed by vines are partly bound to glycosides, making them difficult to detect through sensory evaluation of grapes.
Vineyard washing treatments have not been successful in removing smoke taint compounds. Since smoke compounds are readily transferred from juice to wine during skin contact, mitigation actions during red winemaking don’t seem to be successful. On the other hand, final concentrations in white wines are highly dependent on harvesting and winemaking parameters and techniques. Most of the information reported from Australia has been confirmed by our own experience in 2008.
Applications
The main indicators of smoke taint in both grapes and wine, guaiacol and 4-methylguaiacol, can be used both to screen grapes and assess the intensity of smoke taint in wines. In Australia, grapes have been reportedly downgraded for guaiacol levels in the low ug/kg(ppb) range.
When a wine is suspected to be impacted by smoke, the determination of guaiacol and 4-methylguaiacol can often confirm the presence of taint and its intensity. Knowing the levels of both compounds often helps to make decisions when considering treatments to remove smoke taint from wine. Since significant amounts of guaiacol and 4-methylguaiacol can be released into wine by toasted oak, however, it is often preferable to submit wine that did not have any contact with oak, or alternately from “neutral” barrels.
Grape Sampling
Grape samples can be taken in the vineyard or directly from harvest containers. Beware of spatial variability within the same vineyard, especially if the fire was close by. A good sampling program is essential to ensure that the sample is representative. A sample that contains a minimum of 200 berries, taken from 50 individual vines across a block or vineyard, should provide a representative sampling for smoke taint residue analysis.
Wine Sampling
Samples for analysis should have a minimum volume 60 mL without headspace.
This document is a compilation of information and views from various sources provided for the convenience of our clients. Information in this document is provided "as is" without warranty of any kind, either expressed or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and freedom from infringement. User assumes the entire risk as to the accuracy and the use of this document. This document may be copied and distributed subject to the following conditions: 1) All text must be copied without modification and all pages must be included; 2) All copies must contain ETS's copyright notice and any other notices provided therein; and 3) This document may not be distributed for profit. All trademarks are acknowledged. Copyright ETS Laboratories 2001-2009.
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Smoke Taint Markers in Grapes and Wines - ASEV Presentation Poster |
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Checking Grapes and Wines for “Smoke Taint”
Background
“Smoke Taint” in wines was first identified as a serious problem following the 2003 wildfires in Australia and British Columbia. Subsequent fires in Australia during 2006-07 caused additional losses in the millions of dollars. The California wildfires of 2008, with over 1,700 individual fires at their peak, caused smoke to cover most of Northern California during June and July.
ETS Laboratories developed an analytical tool to screen grapes, even though it was too early to know the extent of “smoke taint” problems from the 2008 California fires. This helped growers and winemakers identify potential problems and take immediate corrective actions whenever possible. In addition, ETS offered analysis of smoke taint markers in juice and wine.
Smoke Taint Markers
“Smoke taint” is caused by a wide range of volatile phenols. Phenols in smoke are absorbed on vines and grapes and end-up in finished wines where they can cause objectionable odors described as “burnt”, “smoked fish”, “salami”, “ash” and “ashtray”.
Guaiacol and 4-methylguaiacol have been identified as the primary indicators of smoke taint. Both appear to be present in all smoke damaged wines and their concentration in unoaked wines usually correlates to the degree of taint present.
Current Research
“Smoke Taint” research has been conducted primarily in Australia and is still in its early stages. Current research and observations suggest that the uptake of smoke compounds is greater immediately post-veraison. Vines do not need to be exposed to thick smoke to produce tainted wines. There is evidence suggesting that smoke taint compounds absorbed by vines are partly bound to glycosides, making them difficult to detect through sensory evaluation of grapes.
Vineyard washing treatments have not been successful in removing smoke taint compounds. Since smoke compounds are readily transferred from juice to wine during skin contact, mitigation actions during red winemaking don’t seem to be successful. On the other hand, final concentrations in white wines are highly dependent on harvesting and winemaking parameters and techniques. Most of the information reported from Australia has been confirmed by our own experience in 2008.
Applications
The main indicators of smoke taint in both grapes and wine, guaiacol and 4-methylguaiacol, can be used both to screen grapes and assess the intensity of smoke taint in wines. In Australia, grapes have been reportedly downgraded for guaiacol levels in the low ug/kg(ppb) range.
When a wine is suspected to be impacted by smoke, the determination of guaiacol and 4-methylguaiacol can often confirm the presence of taint and its intensity. Knowing the levels of both compounds often helps to make decisions when considering treatments to remove smoke taint from wine. Since significant amounts of guaiacol and 4-methylguaiacol can be released into wine by toasted oak, however, it is often preferable to submit wine that did not have any contact with oak, or alternately from “neutral” barrels.
Grape Sampling
Grape samples can be taken in the vineyard or directly from harvest containers. Beware of spatial variability within the same vineyard, especially if the fire was close by. A good sampling program is essential to ensure that the sample is representative. A sample that contains a minimum of 200 berries, taken from 50 individual vines across a block or vineyard, should provide a representative sampling for smoke taint residue analysis.
Wine Sampling
Samples for analysis should have a minimum volume 60 mL without headspace.
This document is a compilation of information and views from various sources provided for the convenience of our clients. Information in this document is provided "as is" without warranty of any kind, either expressed or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and freedom from infringement. User assumes the entire risk as to the accuracy and the use of this document. This document may be copied and distributed subject to the following conditions: 1) All text must be copied without modification and all pages must be included; 2) All copies must contain ETS's copyright notice and any other notices provided therein; and 3) This document may not be distributed for profit. All trademarks are acknowledged. Copyright ETS Laboratories 2001-2009.
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