In a few of my posts, I have alluded to the fact that the different odours that we perceive are actually made up of a number of volatile (gas) chemical compounds. These mixtures can be of anywhere from three to a billion (okay, maybe over exaggerating) chemical components to give a certain smell, like that of soy sauce or maple syrup or wine.
Sotolone is the theme for today’s post!
In this post, I want to talk about an individual aroma compound that is really interesting to me- sotolone (or sotolon). It is a type of lactone, and it’s full chemical name is 3-Hydroxy-4,5-dimethylfuran-2(5H)-one. The interesting part about this molecule is that it smells different at different concentrations! For example, if you were to smell a really strong solution of sotolon, it would smell like curry, or the herb fenugreek.
This is fenugreek: it goes by quite a few other names!
However, if you were to smell more dilute (weaker) solutions of sotolone, it would smell like maple syrup, or caramel, or burnt sugar. How very different- going from something spicy in nature to something quite sweet smelling!
I think I am starting to write my posts based on what I want to eat…
Sotolone can be found in soy sauce, beer, wine, ‘candy cap’ mushrooms, raw cane sugar, and many other foods and beverages, and is the source of the smell of artificial maple syrup. It is also found in the urine of people who suffer from something called ‘maple syrup urine disease’! The disease is “a recessive inherited disorder of branched-chain amino acid metabolism due to deficiency of the branched-chain alpha-keto acid dehydrogenase complex”- which in basic terms means that the sufferer does not have the correct enzyme to break down amino acids (from proteins) correctly in their body, and so produce sotolone which is excreted from the body in urine.
While I can’t find any information as to how we perceive something to smell different due to its concentration, I will leave you with this video: ‘How Do We Smell?’ by Rose Eveleth, on how we take chemicals from the air and turn them into something we can smell.