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WHERE THERE’S FIRE, THERE’S SMOKE: HOW TO MANAGE SMOKE TAINT IN WINEMAKING

Fires in Monterey County are becoming a concern for 2016 vintage quality. In terms of the degree of smoke taint present in wines, the timing of smoke exposure plays a major role, as well the winemaking techniques used.

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Fires in Monterey County are becoming a concern for 2016 vintage quality. In terms of the degree of smoke taint present in wines, the timing of smoke exposure plays a major role, as well the winemaking techniques used.

WHAT IS ‘SMOKE TAINT’?

‘Smoke taint’ is the result of absorption of volatile phenols created by fire smoke by grapes, leaves and vines. Wines made with smoke-tainted grapes are described as having notes of ashtray, smoky, leather, burnt, barbecue, smoked meat or even bacon and salami. Guaiacol and 4-methylguaiacol have been identified as the primary markers in assessing the level of smoke taint in fruit and wines.

According to the Australian Department of Agriculture and Food, there is grapevine seasonal sensitivity to smoke uptake:

  • Shoot formation, from shoots 10 cm in length to flowering: low sensitivity to smoke.
  • Berry formation, pea size berries to 3 days post veraison: low to medium sensitivity to smoke
  • Berry ripening, 7 days post veraison to harvest: high sensitivity to smoke.

They also found that smoke exposure to grapevines can delay fruit ripening resulting in a heterogeneous harvest with lower sugar content. Luckily, there is no carry over from a smoky year to the following vintage, but it could be a potential reduction in crop size.

HOW TO TEST FOR SMOKE TAINT?

Vinquiry Laboratories by Enartis USA has developed a robust method for the quantification of smoke taint markers in grapes, juice and wine. Interferences due to the complex matrix and adducts of guaiacol and 4-methylguaiacol contributed to the difficulty in developing the analysis. However, persistence and the insistence on accurate results obtained a procedure that measures these markers reliably by GC/MS. Vinquiry Laboratories offers analysis for guaiacol and 4-methylguaiacol (Smoke Taint Markers). A representative grape, juice or wine sample is required. Minimum sample volume:  grapes = 5 clusters; juice or wine = 200 mL.

WINEMAKING GUIDELINES FOR AFFECTED GRAPES

Some of these phenols are present in juice as a glyco-conjugated form. During fermentation and ageing, these aromatic compounds can be released via enzymatic and acid hydrolysis. Winemaking techniques can strongly impact the level of smoke taint in wine.

Limit extracting smoke-related compounds

  • Hand harvesting allows you to sort out the leaf material that can release smoke-related compounds and keep berry integrity.
  • Keep fruit cool (50⁰F) to limit the extraction of undesirable compounds.
  • Reduce skin contact and maceration time and use enzymes to optimize the extraction of positive compounds and maximize juice yield. Enartis Zym Color improves polyphenol extraction.
  • Use tannins to compensate for short macerations in red wines. Enartis Tan V enhances body and structure while improving color stability.
  • Whole bunch press has been shown to reduce the extraction of smoke derived compounds.
  • Manage press cycle: low pressure, limit the number of rotations, separation of pressings (~120 gal/ton)

Reduce the content of negative compounds

  • Fining trials are recommended to remove off-flavors in juice or wine. We recommend Fenol Free (activated carbon with high affinity with volatile phenols).
  • Fast clarification of white juice has been shown to reduce the amount of smoke taint compounds. Optimize clarification by using a settling enzyme (Enartis Zym RS) to reduce juice viscosity and an appropriate fining agent to accelerate lees precipitation like Claril SP (Bentonite, PVPP, potassium caseinate and silica).
  • Yeast polysaccharides are known to adsorb aroma compounds responsible for smoke taint character. The Enartis Pro Range can reduce smoke taint precursors while improving mouthfeel and color stability. 
  • Contact Enartis USA for more details on fining trials at (707) 838 6312.

Increase positive aroma production during fermentation

  • Some yeast strains may reduce smoke character without diminishing “fruit” aromas while others may have higher amounts of enzymes that cleave smoke taint precursors, or have higher amounts of pectinase enzymes that break down skin cell walls.
  • Choose a strong aroma-producer yeast and avoid yeast with glycosidase activity:

Red

Enartis Ferm ES 454

Produces elegant wines with ripe red fruit and spicy aromas.

Enartis Ferm Red Fruit

Increases varietal aroma production. Produces intense secondary aromas: violet, blueberry, blackberry, cherry and raspberry.

Enartis Ferm ES 401

Strong ester producer while respecting varietal character. Reduces malic acid (up to 20%).

White

 

Enartis Ferm Aroma White

Strong ß-lyase activity, increases thiol production. Recommended for Sauvignon Blanc and other thiolic varieties.

Enartis Ferm Top Essence

Strong ester producer. Enhances aromatic expression of pear, pineapple, passion fruit, banana and peach.

  • Manage fermentation with an adapted nutrition (see newsletter on yeast nutrition).
  • Increase varietal aromatic precursor content with the addition of Enartis Tan Red Fruit to bring out notes of berries and red fruit in red wines or Enartis Tan Citrus to enhance citrus, zesty aromas in white wines.
  • Enhance ester production by supplying amino acids used by yeast as aromatic precursors. Nutriferm Arom Plus supplements the juice in amino acids that can be used by yeast to synthetize higher alcohols, esters and acetates.
  • Untoasted oak can reduce smoky character intensity and increase wine complexity. Avoid toasted oak as it increases smoky notes.

Improve and balance mouthfeel by using tannins and polysaccharides during fermentation

  • Enartis Tan Fruitan increases structure and fruitiness of red wines while improving color stability. Enartis Tan Elegance contributes to structure and complexity of white wines while ensuring antioxidant protection.
  • Enhance volume and roundness while improving color stability with Enartis Pro Tinto.

Market wine for immediate consumption: The evolution of smoke related characteristics can occur in the bottle over time as wine ages.

METHODS OF REMEDIATION

Many techniques in the industry have been tried to remove smoke taint.

Reverse osmosis has been found to be effective in reduction of volatile compounds but not as effective at eliminating the glycosylated precursors. As a consequence, smoke-related characteristics can reappear in wine over time.

We hope that this information helps you make informed decisions regarding that hopeless moment when you realize there is a smoke effect in your grapes. If you have any questions, please give us a call at (707) 838-6312.

 

 
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