Geosmin (Crunchy.)

Geosmin smells of earth:

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You can smell vanishingly small amounts of it, too - mere nanograms of the stuff! It smells this way for a reason - countless soil bacteria busily produce it in your backyard as you read this.

The first thing I thought of when I started this entry was Demeter's Dirt fragrance. I imagine this has to have some of the stuff in it - I've only ever smelled it briefly in Whole Foods, though.

I love smell because I never fail to marvel at the fact that a pure single molecule can exhibit such complex aromas. My favorite example is acetophenone.

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I wish I had a reason to order some geosmin. =)

By Vince Noir (not verified) on 27 Oct 2008 #permalink

It's also REALLY hard to get rid of (because of its generally extremely low concentrations). It's a fairly common problem in drinking water treatment -- people don't like their drinking water to smell like dirt, so we often have to design in GAC adsorbers or ozone/h2o2/fenton's kinda stuff to get rid of geosmin and 2-mib.

One word: petrichor. Although I think they found that that was made of ~40 different scent molecules.

By Craig Helfgott (not verified) on 28 Oct 2008 #permalink

A big winner is [E,E]-farnesaldehyde, Lily of the Valley. The nitrile is similar and more stable. The scent is counterfeited with bourgeonal.

(-)-[4S,4aS,8aR]-Geosmin is the bane of water districts. With a sensory threshold of 0.1 ng/kg tap water complaints flood in with just a teeny contamination.