4-ethyl phenol

Technical specification

Assessment

The best way to detect ethyl phenol and the signs of Brettanomyces activity in wine is as follows. Cover the sample with your hand and swirl the glass to release the aroma. Remove your hand and take a single long sniff. Repeat as necessary.

Amount of flavour per capsule

1.7 mg per capsule

Threshold

The flavour threshold of 4-ethyl phenol in wine is 300 - 550 µg / l.

Origins

4-Ethyl phenol is a flavour defect of red wine produced by contaminant Brettanomyces (Dekkera) during barrel ageing, and occasionally after bottling. Wines which are low in sulphur dioxide are particularly sensitive to this problem.

Importance

Ethyl phenol Imparts an unpleasant band aid-like character, described as barnyard, medicinal or horsey. The flavour tends to mask more subtle varietal notes in the wine. Insufficient sulphuring of grapes and poor winery hygiene predispose wines to this problem.

CAS registry number

The CAS registry number of 4-ethyl phenol is 123-07-9.

Other names

• p-ethyl phenol
• para-ethyl phenol
• 1-ethyl-4-hydroxybenzene
• 4-ethylphenol
• 1-hydroxy-4-ethyl benzene
• 4-hydroxyethyl benzene
• 4-hydroxyphenyl ethane

Remarks

Ethyl phenol is the characteristic odour of Brettanomyces contamination of wine. It occurs in combination with other Brettanomyces end-products including acetic acid, ethyl acetate, isovaleric acid, and ethyl guaiacol, which smells of smoked bacon or smoked cheese.

Threshold distribution

Capsules per pot

10