Effect of redox mediators on the activity of laccase from Botrytis cinerea against volatile phenols

Abstract

Volatile phenols namely 4-ethylphenol and 4-ethylguaiacol are formed by enzymatic decarboxylation of hydroxycinnamic acids by Brettanomyces yeasts to give vinylphenols and subsequent reduction of the vinyl group to form the correspondent ethylphenols. The presence of these compounds in wine affects negatively its aromatic quality, conferring unpleasant animal and phenolic odor when present in quantities above the olfactory detection threshold [1]. Several methods have been described to remove these undesirable compounds from wines, including the use laccase enzymes [2, 3]. Due to this, the aim of this work was to evaluate the effect of several natural redox mediators on the activity of Botrytis cinerea laccase against these volatile phenols.

The ability of Botrytis cinerea laccase to degrade 4-ethylphenol and 4-ethylguaiacol was studied by incubation with the enzyme in acetate buffer and model wine, and several phenolic compounds were individually assayed as mediators. Quantification of volatile phenols was accomplished by GC-MS analysis.

The only use of the Botrytis cinerea laccase was not effective in reducing or removing these off-flavors and the presence of mediators was required under these conditions. All phenolic compounds tested (caftaric acid, quercetin-3-O-rutinoside, catechin, epicatechin, ferulic acid and quercetin) favored the degradation of volatile phenols, achieving higher 4-ethylguaiacol removal percentages than that for 4-ethylphenol. These preliminary results confirm the activity of this type of enzyme against volatile phenols and provide knowledge on the effects of natural mediators on the biodegradation effectiveness of undesirable substances which may alter the quality of wine.

References

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