Металічні ноти

The smell of metal

The typical metallic smell of metals such as coins, and of blood coming into contact with skin, is due to oct-1-en-3-one. Oct-1-en-3-one is the main compound responsible for the smell of metal, followed by decanal (orange skin, flowery) and nonanal (tallowy, fruity). That the metal itself is being smelled is an illusion. What humans perceive as metallic is really a by-product of metals reacting with skin or with impurities in the metal. The odour results from a metal-induced oxidation of skin lipids, so it is a type of human body odour.

Chemistry

The compounds people smell are aldehydes and ketones, not compounds that contain iron. Oct-1-en-3-one is a ketone analogue of the alkene 1-octene. Oct-1-en-3-one has the formula C₈H₁₄O and a molecular weight of 126.20. It is produced by Uncinula necator, a fungus that causes powdery mildew of grape. Oct-1-en-3-one is the degradative reduction product of the reaction of skin lipid peroxides with Fe²⁺. The skin lipid peroxides form from skin lipid by oxidation, either enzymatically by lipoxygenases or by oxygen in the air.

Other sources of the same odour

Rubbing blood over skin results in a similar metallic smell based on the same scent molecules. Copper has a similar effect, accounting for the metallic smell created by handling coins made of copper alloys. Every person is thought to generate a subtly different blend of odorant molecules when touching metal.

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