Conversion of hydroxycinnamic acids into volatile phenols in a synthetic medium and in red wine by Dekkera bruxellensis

the conversion of p-coumaric acid, ferulic acid, and caffeic acid into 4-ethylphenol, 4-ethylguaiacol and 4-ethylcatechol was studied in dekkera bruxellensis isa 1791 under defined conditions in a synthetic medium and in a red wine. liquid chromatography (hplc-dad) was used to quantify the phenolic acids, and gas chromatography (gc) coupled to a fid detector was used to quantify volatile phenols using a novel analytical methodology that does not require sample derivatization. identification was achieved by gas chromatography-mass detection (gc-ms). the results show that phenolic acids concentration decreases while volatile phenols concentration increases. the proportion of caffeic acid taken up by dekkera bruxellensis is lower than that for p-coumaric or ferulic acid; therefore less 4-ethylcatechol is formed. more important, 4-ethylcathecol synthesis by dekkera bruxellensis in wine has never been demonstrated so far. these results contribute decisively to a better understanding of the origin of the volatile phenols in wines. the accumulation of these compounds in wine is nowadays regarded as one of the key factors of quality control.