Hydroxycinnamic acids 4-vinyl derivatives

Grapes contain several hydroxycinnamic acids, p-coumaric, caffeic, ferulic and sinapic acids, which exist as free acids and esterified with tartaric acid. Saccha-romyces species can take up free acids to produce the corresponding vinyl phenol catalysed by hydroxycinnamate decarboxylase (phenylacrylic acid decarboxylase Padlp) (Fig 8D.11) (Chatonnet et al. 1992b Chatonnet et al. 1993 Edlin et al. 1995). Vinyl phenols are unstable and highly reactive. Dekkera bruxellensis is one of few wine microorganisms that can further reduce vinyl phenols to highly stable ethyl phenols in wine. Vinyl phenols can also react with anthocyanins to form vinyl derivatives, a reaction that is favoured by fermentation yeast having hydroxycinnamate decarboxylase activity (Morata et al. 2006). 

Lactic acid bacteria, including the typical "wine lactic acid bacteria" Leuconostoc oenos (85, 90), can produce ethyl and vinyl derivatives by hydroxycinnamic acid metabolism (91) although, the minimal concentration produced in red wines by Leuconostoc oenos is insignificant compared to the odor threshold (85, 87). 

Vanbeneden, N., Gils, R, Delvaux, R, Delvaux, R R. (2008). Formation of 4-vinyl and 4-ethyl derivatives from hydroxycinnamic acids occurrence of volatile phenolic flavour compounds in beer and distribution of padl-activity among brewing yeasts. Food Chemistry, 107, 221-230. http //dx.doi.Org/10.1016/j.foodchem.2007.08.008. 

Terpinc P, Polak T, Segatin N, Hanzlowsky A, Uhih NP, Abramovic H. 2011. Antioxidant properties of 4-vinyl derivatives of hydroxycinnamic acids. Food Chemistry, 128 62-69. 

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