This post is for the esteemed Magnifico, editor of Saturday Science OND, as a demonstration.
Do ants smell like blue cheese ..., or rotten coconuts, or a doctor’s office?
WHEN AN INSECT has the nick-name of "odorous house ant," you know it's smelly. This ant's scent has been described as blue cheese, rancid butter, or cleaning solution. Inquiring science minds wanted to know: What does it really smell like?
A pair of ant researchers used a public sniff test to try to identify the tantalizing fragrance of Tapinoma sessile, the odorous house ant:
C. Penick & A. Smith. 2015. The True Odor of the Odorous House Ant. American Entomologist 61(2): 85-87.
The plot thickened. Most volunteer “sniffers” did indeed vote “blue cheese”, “rotten coconut” came second, and one young girl thought it smelled like her Doctor’s office.
So what could the common chemical with this very identifiable odour be?
The researchers first of all determined that an ethylated ketone was prevalent in the odour of blue cheese, but coconuts had no indication of this. Until … someone thought of rotting the coconut, by burying it in his garden for several weeks. Upon unearthing it … presto! A blue-green mould grew on its outside, and you should not be at all surprised to know that, yes, the mould emanated ethyl ketones.
But which one?
Further analysis revealed that the primary component of an admittedly complex combination of organic chemicals was the simple Methyl ethyl ketone, or acetone (nail polish remover), a sometime antiseptic which is why the youngster thought of her Doctor’s office.
Methyl ketones are prevalent in some cheeses and, they showed, in rotten coconuts as well; with, surprisingly, Penicillium sp., “which is what gives blue cheese its distinctive colour and flavour”.
The paper ends with the enigmatic conclusion:
"Our results point to blue cheese with a cautious nod to rotten coconut... Or you could say that they smell like coconuts colonized by a Penicillium mold that metabolizes coconut oil to produce an odor similar to blue cheese, but by then, you could have said 6-methyl- 5-hepten-2-one three times fast."
6-methyl- 5-hepten-2-one, C8H14O for the organic chemists here.