Mitigation of smoke taint in wine

Ioan  Pavel Ivanov Gitsov

doi:10.7273/000003961

Grapevines that have been exposed to smoke have higher concentrations of methoxyphenols, due to degradation of lignin upon the burning of plant material. These methoxyphenols are responsible for smoky aromas and flavors and are present as free compounds and bound glycosylated forms. Upon fermentation of impacted fruit, these compounds are extracted and carried over into the finished wine. This phenomenon has a severe impact on wine sensory characteristics, and in turn, on reputations of established wineries and vineyards. In this study, methods for remediation of the free and bound smoke-related compounds were explored. Using gas-chromatography mass-spectrometry, reverse osmosis coupled with adsorption using activated carbon was successful in reducing the peak areas of phenol, 2,6-dimethylphenol, 2-ethyl-4-methylphenol, 2-ethyl-6-methylphenol, syringol, eugenol, and trans-isoeugenol in one treatment of research smoked Merlot wine, but surprisingly, not in the second. Furthermore, treatment of a commercial wine that was exposed to uncontrolled smoke application showed reductions in peak areas for different compounds, as expected, since the conditions of smoke application play a role in which compounds are present. Though it was not analyzed, it is imperative to also monitor beneficial aroma compounds present in the wine when treating smoke tainted wines, due to the low specificity of activated carbon. Enzymatic hydrolysis as a method for reducing the bound fraction of smoke compounds was also explored. Using a collection of ten enzymes with varying glycosidase, peroxidase, and pectinase activities, smoked and unsmoked permeate fractions were treated. Efficacy of treatment was determined using ultra-high pressure liquid chromatography-quadrupole time of flight-mass spectrometry to monitor peak areas for five bound compounds and five free compounds of interest. Of the ten enzymes analyzed, AR2000, Scottzyme BG, and Lallzyme Beta were found to be the most successful in liberating bound compounds following a 2h treatment time. As these three enzymes are a cocktail of enzymatic activities, advertised as pectinases with glycosidase and esterase side activities, future work should be carried out to determine which enzyme is primarily responsible for hydrolysis. Since these enzymes are readily used in the wine industry, however, implementation for treatment of smoke tainted wines is easy and inexpensive.

Mitigation of smoke taint in wine

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