''trans''-4,5-Epoxy-('' E'')-2-decenal (E2D)is an oxygenated α,β-unsaturated

aldehyde In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

found in mammalian blood that gives blood its characteristic metallic odor. It is used by predators to locate blood or prey. ''trans''-4,5-Epoxy-('' E'')-2-decenal is almost certainly found in all mammals. Humans can smell it at a concentration of 1.5 pg/L in air, at 15 ng/L in water and 1.3μg/L in oil. It was permitted as a food flavouring in the EU until it was prohibited on 11 July 2017 on the grounds of possible genotoxicity, as observed from rat livers. It can be formed during baking fats that contain

linoleic acid Linoleic acid (LA) is an organic compound with the formula . Both alkene groups () are ''cis''. It is a fatty acid sometimes denoted 18:2 (n−6) or 18:2 ''cis''-9,12. A linoleate is a salt or ester of this acid. Linoleic acid is a polyunsat ...

. 13-Hydroperoxy-9,11-octadecadienoic acid and 9-hydroperoxy-10,12-octadecadienoic acid are intermediates in the process. The aldehyde also forms in cooked beef when it sits in the refrigerator for too long contributing to a stale smell. It is also an important part of the smell of raw and cooked

mutton Lamb and mutton, collectively sheep meat (or sheepmeat) is one of the most common meats around the world, taken from the domestic sheep, ''Ovis aries'', and generally divided into lamb, from sheep in their first year, hogget, from sheep in thei ...

. Humans are more sensitive to the smell of ''trans''-4,5-Epoxy-(''E'')-2-decenal than mice.

References

{{DEFAULTSORT:Epoxy-(E)-2-decenal, trans-4, 5- Unsaturated compounds Epoxides Conjugated aldehydes