Where does the metallic smell we usually smell come from?
In fact, this smell comes from the chemical reaction between sebum and iron. When we touch keys, coins, or metal railings, we often smell a strange metallic smell on our hands.
Is this metallic smell really the smell of metal?
In fact, pure metal itself has no odor.
The structure of metals determines that they do not easily volatilize into gases, and therefore do not become part of the odor molecules.
Scientists have studied the odor of iron products, and found that after human skin comes into contact with iron products, the interaction of lipids and iron on the skin can produce a small number of small molecule carboxyl compounds, which are the source of odor.
Specifically, when sebum and metal come into contact, they oxidize the metal into divalent ferrous ions, which break down lipid peroxides into carboxyl molecules.
The main source of metallic flavor is 1-octen-3-one.
However, human beings know the truth about metallic taste, which is only a short decade old.
In 2006, Virginia Tech and State University chemists Dietmar Glindemann and Andrea M. Dietrich discovered the origin of metallic taste by mass spectrometry.
In addition, because the organic composition and proportion of each person's sebum are different, the composition of skin secretions and body surface microflora at different ages is also different, so the metal smell that each person smells after touching the metal is also different.
"Extended Reading" - Why does copper have a strange smell?
The oils on the surface of the skin produce some kind of oxidizing unstable organic matter under the action of ultraviolet rays and some enzymes.
These organic matter come into contact with divalent metal ions left on the skin after the metal is corroded by sweat, and a chemical reaction occurs. The human sense of smell is very, very sensitive to specific volatile substances in the products of the reaction, which is what we often call metallic taste.
There must be an evolutionary reason why humans are unusually sensitive to this smell. A possible explanation is that we need this sensitive sense of smell to detect blood.
The iron in hemoglobin can cause the same reaction.
Whether it's protecting yourself or hunting, this ability is important.