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

Abstract

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.

Novel analytical approach to assess the profile of volatile phenols in Portuguese red wines

“…Owing to the sequential activity of two enzymes (cinnamate decarboxylase and vinylphenol reductase), free hydroxycinnamic acid precursors, p ‐coumaric, ferulic and caffeic acids, are decarboxylated into hydroxystyrenes, 4‐vinylphenol, 4‐vinylguaiacol and 4‐vinylcatechol, respectively, which are then reduced to their corresponding ethyl derivate forms 4‐ethyphenol, 4‐ethylguaiacol and 4‐ethylcatechol, respectively (Carrillo and Tena , Cabrita et al ). The first step of this process is performed by cinnamate decarboxylase, produced by Brettanomyces populations, essentially B. bruxellensis , but can also be produced by the fermentation yeast Saccharomyces cerevisiae and many other microorganisms such as Rhodotorula , Candida and Cryptococcus (Swiegers et al , Sumby et al ).…”

Harnessing improved understanding ofBrettanomyces bruxellensisbiology to mitigate the risk of wine spoilage

“…HCA precursor less efficiently than coumaric and ferulic acids (Harris et al 2008, Cabrita et al 2012, Schopp et al 2013). Furthermore, the impact of 4-EC in wine may not be as significant as that observed for 4-EP and 4-ethylguaiacol (4-EG); in cider the detection threshold of 4-EC was more than tenfold higher than that of 4-EP (Buron et al 2012).…”

Molecular and biochemical aspects ofBrettanomycesin brewing

“…The synthesis of volatile phenols occurs in two enzymatic sequential steps: (a) decarboxylation of p‐ coumaric and ferulic acids to their corresponding hydroxystyrenes (4‐vinylphenol and 4‐vinylguaiacol) by cinnamate decarboxylase; and (b) reduction of these molecules to 4‐ethylphenol and 4‐ethylguaiacol by vinylphenol reductase (Figure ). In addition, 4‐ethylcatechol is formed from caffeic acid in low amounts (Figure ) . Notably, some S. cerevisiae strains also form hydroxystyrenes from hydroxycinnamic acids but are unable to further transform these compounds to the phenols.…”

“…linalool) . Moreover, Brettanomyces species produce volatile phenols such as 4‐vinylguaiacol (clove flavour) and tetrahydropyridines (mousy/cracker biscuit‐like flavour) (Figures and ) .…”