Furfural

Furfural (from Latin furfur, bran), also known as furfurol, is a naturally occurring, colourless, liquid heterocyclic aldehyde compound with a caramel-like odour, which turns slightly brown when exposed to light and air and has the empirical formula: C5H4O2. Furfural is slightly soluble in ethanol and ether; soluble in water. Furfural occurs naturally as a constituent of essential oils e.g. in bran, corncobs, cloves and peanut shells.

Furfural is formed during the heating of carbohydrates from mono- and disaccharides via the corresponding 3-deoxypentoses and, together with substituted furfurals, is the main volatile product in caramelization.