4-ethyl phenol

1.0 mg per capsule

Band aid, like a cider contaminated with Brettanomyces

Certified cider flavour standard used to train professional tasters to recognize and scale the intensity of ethyl phenol character. Ethyl phenol is produced by contaminant Brettanomyces yeasts and sometimes by lactic acid bacteria. This compound imparts an unpleasant 'band-aid' note to cider, occasionally described as 'horse-like' or 'barnyard'. At low levels ethyl phenol contributes to product complexity.

Food grade | free from sensory impurities | extensively tested | safe to smell and taste.

Flavour cards

Flavour standard information

Technical specification

The best way to evaluate band aid, horsey flavour notes caused by growth of Brettanomyces in cider 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
1.0 mg per capsule
The flavour threshold of 4-ethyl phenol in cider is 300 µg / l.
4-Ethyl phenol is produced by contaminant Brettanomyces (Dekkera) yeasts and, occasionally by lactic acid bacteria, during cider production. Ciders which are low in sulphur dioxide are particularly sensitive to growth of such microorganisms.
4-Ethyl phenol imparts an unpleasant band aid-like character to cider, described by some as ‘barny’ or ‘horsey’. At low levels the odour resembles that of leather. In traditional ciders, growth of Brettanomyces can add complexity to the product, helping to differentiate it from other ciders.
CAS registry number
The CAS registry number for 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
Ethyl phenol often occurs in combination with other compounds produced by Brettanomyces, including acetic acid, ethyl acetate, isovaleric acid, and other phenolic compounds such as ethyl guaiacol.
Threshold distribution
Capsules per pot
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