Butyric acid (4 carbon atoms), from Greek word βούτυρος, meaning butter, was discovered by Lieben and Rossi in 1869.
It is a saturated fatty acid (no double bond so in shorthand 4:0) member of sub-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
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.
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.
- Akoh C.C. and Min D.B. “Food lipids: chemistry, nutrition, and biotechnology” 3th ed. 2008
- Chow Ching K. “Fatty acids in foods and their health implication” 3th ed. 2008