Smoke Taint and MirrorsSmoke Taint and Mirrors

Some observations about smoke effect, its cause, and its removal

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Guaiacol in BerriesGuaiacol in Berries((Samples analyzed at ETS from Aug to Oct 2008)Samples analyzed at ETS from Aug to Oct 2008)

Guaiacol (ug/kg)

16%

38%

35%

11%

< 0.50.5-1.92.0-6.0>6.0

Winesecrets’ ExperienceWinesecrets’ Experience

Smoke removal in British ColumbiaTechnology transferOperations, lessons learnedStarted Mendo removal operations in late

2008To date, over 1,500,000 gallons

successfully restored

Smoke CompositionSmoke Composition

Pyrolysis of burning material also results in production of a large amount of hydrocarbons, both aliphatic (methane, ethane, ethylene, acetylene) and aromatic (benzene and its derivates, polycyclic aromatic hydrocarbons; e.g. benzo[a]pyrene, studied as a carcinogen, or retene), terpenes. Heterocyclic compounds may be also present. Heavier hydrocarbons may condense as tar.Presence of sulfur can lead to formation of e.g. hydrogen sulfide, carbonyl sulfide, sulfur dioxide, carbon disulfide, and thiols; especially thiols tend to get adsorbed on surfaces and produce a lingering odor even long after the fire. Partial oxidation of the released hydrocarbons yields in a wide palette of other compounds: aldehydes (e.g. formaldehyde, acrolein, and furfural), ketones, alcohols (often aromatic, e.g. phenol, guaiacol, syringol, catechol, and cresols), carboxylic acids (formic acid, acetic acid, etc.).The visible particles in such smokes are most commonly composed of carbon (soot). Other particulates may be composed of drops of condensed tar, or solid particles of ash. The presence of metals in the fuel yields particles of metal oxides. Particles of inorganic salts may also be formed, e.g. ammonium sulfate, ammonium nitrate. Many organic compounds, typically the aromatic hydrocarbons, may be also adsorbed on the surface of the solid particles.Some components of smoke are characteristic of the combustion source. Guaiacol and its derivatives are products of pyrolysis of lignin and are characteristic of wood smoke; other markers are syringol and derivates, and other methoxy phenols. Retene, a product of pyrolysis of conifer trees, is an indicator of forest fires. Levoglucosan is a pyrolysis product of cellulose. Hardwood vs softwood smokes differ in the ratio of guaiacols/syringols.

Smoke AnalysisSmoke Analysis

ETS◦Eric Herve

Vinquiry◦Jerome Lillis

Field analysis◦UV Spec◦Wine glass

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Markers

Guaiacol and 4-MethylguaiacolGuaiacol and 4-Methylguaiacol

• G : smoky, charred

• 4MG : smoky, spicy

Smoke Taint CharacteristicsSmoke Taint Characteristics

Aromas: Ashy, tar, BBQ, creosote, cold fireBitter phenolic, metallic taste

In Whites:◦Occasionally taste in grapes in vineyard◦Aromas found early in white juice

In Reds:◦Occasionally taste in grapes in vineyard◦Sometimes discovered during

fermentation◦Easily spotted post ML

Available ResearchAvailable Research

Most papers concern analysis for guiacolsUnderstanding uptake mechanismsDeveloping predictive model of guiacol levels

in grapes and finished wine.Most research from Australia:

◦Australian Government Grape and Wine Research Corporation

◦Australian Wine Research InstituteAuthors most active:

◦K. R. Kennison◦K. L. Wilkinson

Canadian ResearchCanadian Research

◦ Effect of Pre- and Postveraison Smoke Exposure on Guaiacol and 4-Methylguaiacol Concentration in Mature Grapes

◦ Stacey I. Sheppard1,1, Manpreet K. Dhesi2,2 and Nigel J. Eggers3,* 1, 2 Research assistant and 3 Associate professor, Chemistry, Earth & Environmental Sciences, Irving K. Barber School of Arts & Sciences, University of British Columbia, Okanagan, 3333 University Way, Kelowna, BC, V1V 1V7 Canada.

◦ * Corresponding author (email: nigel.eggers@ubc.ca ) ◦ Chardonnay, Merlot, and Pinot gris grapes were treated with smoke

generated by the combustion of Ponderosa pine at preveraison,

postveraison, and maturity. Guaiacol and 4-methylguaiaol concentrations

were determined in the mature harvested grapes using a stable isotope dilution assay. Both guaiacol and 4-methylguaiacol were sorbed by the grapes during the smoke treatments and remained until the grapes were harvested. There was a general trend for increasing sorption of guaiacol and 4-methylguaiacol as grapes matured. A positive linear correlation was observed between the guaiacol:4-methylguaiacol ratio and guaiacol concentration for all smoke-treated grape samples that had concentrations

above detection limits. Guaiacol concentrations ranged from 2 to 26 µg/L. These grapes could yield a wine where the concentrations exceed the detection threshold of guaiacol and the concentrations were of the same order as that resulting from contact with oak. An hour of smoke exposure would have an impact on the sensory characteristics of the resulting wines.

Research (most pertainent)Research (most pertainent)

Department of Primary Industries Victoria – Mark Krstic & John Wihting 2003

British Columbia Fire (Okanagan Valley) AWS Work experience 2003

UoA Analysis and Amelioration of Smoke Taint – Dr. Kerry Wilkinson2007

Technical Workshop Smoke Taint – AU Government & Mark Krstic 2008

Western Australia Department of Agriculture and Food 2009Bushfire Generated Smoke Taint in Grapes and Wine – Kristen Kennison

Western Australia Department of Agriculture and Food 2009Latest developments – Kristen Kennison

Australia: what is knownAustralia: what is known

What we know · Smoke taint/effect carryover from one season to another is not a problem. · Guaiacol indicator compound involved , but not necessarily responsible for smoke taint (it is also found in oaked wine products). · Safe to burn after grape harvest (the date varies depending on growing region and grape variety). · Taint compounds durable in wine (that is compounds only get worse with age of wine). · Guaiacol and 4-methylguaiacol increases during fermentation as it is extracted into solution. · Problems in current guaiacol and 4-methylguaiacol analytical methods (some grape samples can come back with not detected levels of indicator compounds, but still show taint in wine). · Highly variable between varieties (some grape varieties more sensitive than others). · Cumulative affect of smoke (increased smoke exposure = increased risk of being affected). · Smoke more from a filtration perspective, but we don’t know all the taint compounds. affects grape vine physiology (i.e. yield and photosynthesis). · Peak in sensitivity at 7 days post-veraison from WA research trials. · Wines from white grapes is less affected than wine from red grapes (this is due to skin contact during fermentation in red winemaking) · Hand harvesting better than machine harvesting in regards to expression of taint compounds in wine. · Reverse osmosis does work

Australia: what is not knownAustralia: what is not known

·Mode of smoke entry into vine and fruit ·Sensitivity and timing of vines to smoke exposure · Effect of distance, composition, concentration and duration and entry into the vine

(models) ·Fire source (fuel types), smoke composition and affect on vines ·Localization of smoke taint compounds in grape berries ·Pre-cursor and conjugates in grapes (what are they?)

Smoke removal researchSmoke removal research

Only one paper focused on removal methodology

Kerry Wilkinson, The University of Adelaide, The Analysis and Amelioration of Smoke Taint

Conclusion: RO and Carbon adsorbsion reduced guiacol indicators (12 to 5 ppb), no effect on wine quality parameters, profound effect on sensory qualities

Smoke Removal TechnologiesSmoke Removal Technologies

Reverse Osmosis◦Pressure/pore size◦Carbon block◦Granulated carbon◦Resin

AlternativesAlternatives

Harvesting/grape handling◦ Pick at night◦ Washing not effective◦ Reduce skin contact

Fining◦ Vinquiry has a product that combines eisenglass,

bentonite and carbon that has been effective at low levels of guiacol

◦ Other fining strategies may help, no evidence of consistent results

Masking with oak◦ No record of effectiveness

Blending◦ If you can afford it

Frequently Asked QuestionsFrequently Asked Questions

The best questions are those yet unasked!