butyric acid

Technical specification

Assessment

The best way to detect butyric acid 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

9.0 mg per capsule

Threshold

The flavour threshold of butyric acid in cider is 3 mg / l.

Origins

The origin of butyric acid in cider-making is unclear. However, it is likely that it is produced in apples of poor quality prior to pressing due to the action of contaminant bacteria, including Bacillus and Clostridium.

Importance

The odour of butyric acid is reminiscent of that of rancid butter or baby vomit. The flavour of affected ciders can be worsened by the presence of 2,3-butanedione, or improved by ethyl butyrate derived from metabolism of butyric acid by yeast during fermentation.

CAS registry number

The CAS registry number for butyric acid is 107-92-6.

Other names

• butanoic acid
• butanic acid
• n-butanoic acid
• 1-butyric acid
• n-butyric acid
• ethyl acetic acid
• 1-propane carboxylic acid
• propyl formic acid

Remarks

The intensity of butyric acid flavour in cider increases with decreasing cider pH value.

Threshold distribution

Capsules per pot

10