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.
Authors: Pérez-Navarro José1,2, Osorio Alises María3, Paniagua Martínez Tania3, Giménez Pol4, Canals Joan Miquel4, Zamora Fernando4, Sánchez-Palomo Eva3, González-Vinas Miguel Ángel3 and Gómez-Alonso Sergio2,3
1Higher Technical School of Agronomic Engineering, University of Castilla-La Mancha.
2Regional Institute for Applied Scientific Research (IRICA), University of Castilla-La Mancha
3Faculty of Chemical Sciences and Technologies, University of Castilla-La Mancha
4Faculty of Oenology, Rovira i Virgili University
*corresponding author: jose.pnavarro@uclm.es
References:
1. Petrozziello M, Asproudi A, Guaita M, Borsa D, Motta S, Panero L, Bosso A. 2014. Influence of the matrix composition on the volatility and sensory perception of 4-ethylphenol and 4-ethylguaiacol in model wine solutions. Food Chemistry 149: 197–202.
2. Lustrato G, De Leonardis A, Macciola V, Ranalli G. 2015. Preliminary lab scale of advanced techniques as new tools to reduce ethylphenols content in synthetic wine. Agro FOOD Industry Hi Tech 26:51-54.
3. Moeder M, Martin C, Koeller G. 2004. Degradation of hydroxylated compounds using laccase and horseradish peroxidase immobilized on microporous polypropylene hollow fiber membranes. Journal of Membrane Science 245:183-190.
Keywords: 4-ethylphenol, 4-ethylguaiacol, enzyme, phenolic compounds, fungi
