Butyric acid: structure, properties, and food sources

Butyric acid, a carboxylic acid with a 4 carbon chain, was discovered by Lieben and Rossi in 1869. It was named from the greek word βούτυρος, meaning butter.
It belongs to the group of saturated fatty acids (no double bond, so its shorthand notation is 4:0). It is also a member of the group called short chain fatty acids (SCFA), up to 6 carbon atoms.

Molecular weight: 88.10512 g/mol
Molecular formula: C4H8O2
IUPAC name: butanoic acid
CAS registry number: 107-92-6
PubChem: 264

Skeletal formula of butyric acid, a saturated fatty acid
Butyric Acid

In purified form, it is a colorless oily liquid soluble in water, with melting point at -7.9 °C (17.78 °F; 265.25 K) and boiling point at 163.5 °C (326.3 °F; 436.65 K) at 760 mmHg.

ethylacetic acid
propylformic acid
1-propanecarboxylic acid

Food sources of butyric acid

It occurs as glycerol ester in animal fats like those present in butter (it makes up 3-4 percent of butter fat), Parmigiano and other cheeses and plant oils.
The unpleasant odor of rancid butter is due to hydrolysis, and subsequent liberation, of this acid from glycerol.

  1. Akoh C.C. and Min D.B. “Food lipids: chemistry, nutrition, and biotechnology” 3th ed. 2008
  2. Chow Ching K. “Fatty acids in foods and their health implication” 3th ed. 2008

Biochemistry, metabolism, and nutrition