4-Vinylphenol is a phenolic

Natural phenol

Natural phenols, bioavailable phenols, plant phenolics, low molecular weight phenols or phenoloids are a class of natural products. They are small molecules containing one or more phenolic group. These molecules are smaller in size than polyphenols, containing less than 12 phenolic groups...

 compound found in wine

Wine

Wine is an alcoholic beverage, made of fermented fruit juice, usually from grapes. The natural chemical balance of grapes lets them ferment without the addition of sugars, acids, enzymes, or other nutrients. Grape wine is produced by fermenting crushed grapes using various types of yeast. Yeast...

 and beer

Beer

Beer is the world's most widely consumed andprobably oldest alcoholic beverage; it is the third most popular drink overall, after water and tea. It is produced by the brewing and fermentation of sugars, mainly derived from malted cereal grains, most commonly malted barley and malted wheat...

. It is produced by the spoilage yeast

Yeast

Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...

 Brettanomyces

Brettanomyces

Brettanomyces is a non-spore forming genus of yeast in the family Saccharomycetaceae, and is often colloquially referred to as "Brett". The genus name Dekkera is used interchangeably with Brettanomyces, as it describes the teleomorph or spore forming form of the yeast. The cellular morphology of...

. When it reaches concentrations greater than the sensory threshold

Sensory threshold

Sensory threshold is a theoretical concept used in psychophysics. A stimulus that is less intense than the sensory threshold will not elicit any sensation...

, it can give the wine aromas described as barnyard, medicinal, band-aid

Band-Aid

Band-Aid is a brand name for Johnson & Johnson's line of adhesive bandages and related products. It has also become a genericized trademark for any adhesive bandage in Australia, Brazil, Canada, India and the United States....

s, and mousy. In wine, 4-vinylphenol can react with other molecules, such as anthocyanidin

Anthocyanidin

Anthocyanidins are common plant pigments. They are the sugar-free counterparts of anthocyanins based on the flavylium ion or 2-phenylchromenylium, which is a type of oxonium ion . They form a large group of polymethine dye. In particular anthocyanidins are salt derivatives of the...

s, 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

4-Ethylphenol

4-Ethylphenol, often abbreviated to 4-EP, is a phenolic compound with the molecular formula C8H10O. 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,...

 is produced from the precursor p-coumaric acid

Coumaric acid

Coumaric acid is a hydroxycinnamic acid, an organic compound that is a hydroxy derivative of cinnamic acid. There are three isomers, o-coumaric acid, m-coumaric acid, and p-coumaric acid, that differ by the position of the hydroxy substitution of the phenyl group...

. 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

Growth medium

A growth medium or culture medium is a liquid or gel designed to support the growth of microorganisms or cells, or small plants like the moss Physcomitrella patens.There are different types of media for growing different types of cells....

, enabling the positive identification of Brettanomyces by smell.

See also

• 4-Ethylguaiacol
• Wine fault
  Wine fault
  A wine fault or defect is an unpleasant characteristic of a wine often resulting from poor winemaking practices or storage conditions, and leading to wine spoilage. Many of the compounds that cause wine faults are already naturally present in wine but at insufficient concentrations to adversely...
  
  
• Wine chemistry
  Wine chemistry
  Wine is a complex mixture of chemical compounds in a hydro-alcoholic solution with a pH around 3.- Types of natural molecules present in wine :* Acids in wine* Phenolic compounds in wine* Proteins in wine* Sugars in wine* Tryptophol and amino acids derivatives...
  
  
• Poly-4-vinylphenol
  Poly-4-vinylphenol
  Poly-4-vinylphenol, also called polyvinylphenol or PVP, is a plastic structurally similar to polystyrene.PVP is used eg. in electronics, as a dielectric layer in organic transistors in eg. organic TFT LCD displays. Thin films of cross-linked PVP can be used in this application, often in combination...
  
  (polyvinylphenol or PVP) is a plastic structurally similar to polystyrene.

External links

• 4-Ethylphenol oral toxicity data