Formula C8H8O | Molar mass 120.15 g/mol | |
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4-Vinylphenol is a phenolic compound found in wine and beer. It is produced by the spoilage yeast Brettanomyces. When it reaches concentrations greater than the sensory threshold, it can give the wine aromas described as barnyard, medicinal, band-aids, and mousy. In wine, 4-vinylphenol can react with other molecules, such as anthocyanidins, to produce new chemical compounds. In white wines vinylphenols are dominant (4-vinylphenol 70-1 150 μg/l, 4-vinylguajacol 10-490 μg/l) whereas, in red wines, it's the corresponding ethyl-phenols.
Biochemistry
4-Ethylphenol is produced from the precursor p-coumaric acid. Brettanomyces converts this to 4-vinylphenol via the enzyme cinnamate decarboxylase. 4-Vinylphenol is further reduced to 4-Ethylphenol by the enzyme vinyl phenol reductase. Coumaric acid is sometimes added to microbiological media, enabling the positive identification of Brettanomyces by smell.