Smoke Taint – It’s Complicated!

WATER ANALYSIS: Drinking/Potable, Waste/Effluent and Irrigation Water
May 20, 2016
MCC Wines: Dosage
August 15, 2016

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This morning we were at the 2016 SAWWV/SASEV International Conference listening to and learning from Kerry Wilkinson from the University of Adelaide in Australia. Kerry has 10 years of experience working with and understanding smoke taint and its practical implications for winemaking.

We’d like to share with you some of her take home messages.

Measuring guaiacol and 4-methyl guaiacol is not always a reliable indicator of the potential for smoke taint in your wine.

  • The volatile phenols (guaiacol and 4-methyl guaiacol) are only released from their glycoconjugate precursors during fermentation and maturation.
  • The glycoconjugate precursors persist into the wine, meaning that smoke taint is something that may continue to develop over the life of the wine. In one of her trials, glycoconjugate precursors were still present after 6 years of bottle maturation.
  • It is possible to hydrolyse the precursors at the lab into their volatile phenols, but this would give guaiacol and 4 methyl guaiacol results that indicate the full potential of smoke taint, most of which will not be realized during the life of the wine.
  • Measuring glycoconjugate precursors also presents problems, as it has been shown that there is no real correlation between glycoconjugate levels in fruit and guaiacol/4-methyl guaiacol levels in wine.
  • Guaiacol and 4-methyl guaiacol are only 2 of the compounds, among many, that contribute to the total smokey/ashy taste associated with smoke taint. The smoke taint taste is likely to be a synergy between all relevant compounds, and may not necessarily be associated with only high guaiacol levels
  • Note that Shiraz has naturally occuring high levels of guaiacol. This needs to be taken into account when measuring guaiacol from smoke in Shirz wines.

Do mini-ferment trials pre-harvest (with skin contact) to understand the potential implications of a fire.

  • This is still the best and most reliable way to assess the extent of potential smoke taint.
  • But be aware that early harvesting can give false negatives – research has shown that harvesting earlier may result in lower levels of volatile phenols and less smoke taint, especially in white varieties.

Your oaking regime will affect your smoke-taint analysis results.

  • Guaiacol and 4-methyl guaiacol are two of the aroma compounds associated with oak contact during fermentation and/or maturation.
  • When interpreting results smoke taint analysis results, you will need to take into account any oak influence that may increase the levels of these compounds.
  • Oak can contribute up to 40-50 ppb of guaiacol.

Removing smoke taint compounds.

  • Trials with reverse osmosis and carbon fining have both demonstrated success in significantly reducing the levels of the volatile phenols.
  • BUT ….. neither technique is able to remove the glycoconjugate precursors, meaning that the taint may potentially return as the wine ages.