Volatile Phenols in Wine

Ethyl phenols are a result of enzymatic activities linked to the decarboxylation of cinnamic acids and the subsequent reduction in vinyl phenols caused by the Brettanomyces/Dekkera yeast genus (Chatonnet et al., 1992), apart from very small quantities produced in peculiar 

it must be considered as the most critical volatile phenol in red wine. 4-EG was also described in beer as sweet (Meilgaard, 1975). Ethylphenols are usually present in wine with a 4-EP/4-EG ratio ranging from 3.5 to 16 (Chatonnet et al., 1992 Pollnitz et al., 2000 Alessandria et al., 2005 Nicolini et al., 2006). 

the mixture is filtered thorough a 1.5 xm glass microfibre and diluted to 100mL with 1% PEG - 5% NaHCOs solution prior to the IAC purification (MacDonald et al., 1999). 

Another SPE method for sample preparation is by C18 cartridge (Zollner et al., 2000). Ten milliliters of wine is applied to a 100-mg cartridge previously activated by the passage of 5 mL methanol followed by 5 mL water. After the sample loading, the column is washed with 2mL water then the stationary phase is dried. OTA is recovered by 1.25 mL of methanol alternatively, methanol/acetic acid 99.5 0.5 solution (Saez et al., 2004) or 3mL of ethyl acetate/methanol/acetic acid 95 5 0.5 (Chiodini et al., 2006), can be used. The solvent is evaporated and the residue redissolved as reported above. 

Liquid-liquid extraction of OTA from the wine can be also performed (Zimmerli and Dick, 1996). A volume of 5 mL wine is mixed with 10 mL of aqueous solution containing 3.4% orthophosphoric acid (85%) and 1.18 g of NaCl, and extraction is performed twice with 5mL of chloroform each. The organic phases are combined, the solvent is removed under vacuum and the residue is redissolved in 5 mL of phosphate buffer solution (NaCl 120 mM, KC1 2.7 mM, phosphate buffer 10 mM, pH 7.4) prior to purification on IAC cartridge. 

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More potent yeasts responsible for spoilages of wines with volatile phenols are of Brettanomyces/Dekkerra type that can produce the vinyl phenols and ethyl phenols of hydroxyl cinnamic acids. Ribdreau-Gayon et al. (2000) give an overview on this topic. Another source of volatile phenols is the oak wood of barrel and oak chips. These phenols are characterized by smoked and toasted aromas. Important volatile phenols in wine are depicted in Fig. 9C.4. 

Table 11.5 Metabolic activity of microorganisms related with production of volatile phenols in wine industry... 

Larcher, R., Nicolini, G., Puecher, C., Bertoldi, D., Moser, S., Favaro, G. (2007). Determination of volatile phenols in wine using high-performance liquid chromatography with a coulometric array detector. Anal. Chim. Acta, 582, 55-60. 

Mejias, R.C., Matin, R.N., Moreno, M.V.G., Barroso, C.G. (2003). Optimisation of headspace solid-phase microextraction for the analysis of volatile phenols in wine. J. Chromatogr. A, 995, 11-20. 

Dubois, P. (1983) Volatile Phenols in Wines, in Flavour of distilled beverages, origin and development, J.R. Piggot (Ed.) Chichester Ellis Horwood. 

The experimental conditions for MHS-SPME-GC/MS/MS of volatile phenols in wines are reported in Table 5.14. The MS/MS parameters and method performances are reported in Table 5.15. 

TABLE 5.15. Multiple Headspace SPME-GC/MS/MS Method (n = 3) for Analysis of Volatile Phenols in Wines MS/MS Parameters and Performances"... 

Dubois P. (1983) Volatile phenols in wines. Flavour of Distilled Beverages. Origin and Development. Piggott J.R. Ed., Ellis Horwood, Chichester, p. 110. 

Dubois P.J. (1983) Volatile phenols in wine. In Elavour of Distilled Beverages (ed. J.R. Piggott). Soc. Chem. 

Diez, J. Dominguez, C. Guillen, D.A. Veas, R. Barroso, C.G. (2004). Optimisation of stir bar sorptive extraction for the analysis of volatile phenols in wines. Journal of Chromatography A1025,263-267... 

Benzene compounds. Benzene compounds are an important group in varietal aroma, abimdant in wines, including aromatic alcohols, aldehydes, volatile phenols and shikimic acid derivates. The volatile phenols in wines can come from grapes, both as free and bound aroma, or be generated during the alcoholic fermentation by chemical reactions such as phenolic add degradation, or in the case of vinylphenols due to brettanomyces contamination (Suarez et al., 2007). Volatile phenols are considered characteristic components of wine aroma, although their influence on the final product may be positive or... 

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