Mangosteen

@frozengelato.bsky.social

she/her | current big interests: kirby, pokemon, umamusume, vocaloid, deltarune, love live | so-called "franflam scholar" | mostly a lurker | sometimes i do translations of kirby books for fun, find them at https://mangospot.carrd.co/

official kirby english website is so washed that they still use this dated 2008 description where the major selling point is that Kirby stars in the Super Smash Bros series !!

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who wants to learn a scent thing I just learned geosmin is the compound responsible for the smell of rain on dry soil which I already knew but apparently we're 200000x more sensitive to it than sharks are to blood, a dilution equivalent to 1 teaspoon in 200 olympic pools????

Geosmin (CAS 19700-21-1, C₁₂H₂₂O, MW 182.30) is a bicyclic sesquiterpene alcohol — specifically, (4S,4aS,8aR)-4,8a-dimethyloctahydronaphthalen-4a(2H)-ol. It is the principal odorant of wet earth. Not an abstraction: the actual molecule your nose detects when rain lands on dry soil, when a beetroot is sliced open, when a Streptomyces colony sporulates in garden compost.

The compound was isolated and named in 1965 by Nancy N. Gerber and Hubert A. Lechevalier at Rutgers University, from cultures of Streptomyces griseus. The name derives from Greek: geō (earth) + osmḗ (smell). Gerber elucidated its structure in 1968 as trans-1,10-dimethyl-trans-9-decalol. Its biosynthesis — from farnesyl diphosphate via germacradienol, through a bifunctional terpene synthase — was not fully resolved until 2007 by Jiang, Cane et al.

Human sensitivity to geosmin is extraordinary. The detection threshold of the natural (−)-enantiomer sits between 5 and 15 parts per trillion — roughly one teaspoon dissolved in 200 Olympic swimming pools. The (+)-enantiomer is approximately 11 times less potent. This hyper-sensitivity is not accidental: geosmin signals the presence of water in soil, which held obvious survival value for early hominids. The olfactory receptor OR11A1 has been identified as the primary detector.

Geosmin is produced by Streptomyces (actinobacteria), several genera of cyanobacteria, and certain fungi including Penicillium species. It is the molecule behind the earthy flavour of beetroot and the muddy taint in catfish raised in pond aquaculture. In water treatment, its presence at concentrations as low as 10 ng/L triggers consumer complaints — a persistent headache for municipal utilities worldwide.To put that in context, a shark can smell blood at one part per million. That means human noses are 200,000X more sensitive to geosmin, which is also the source of the earthy taste in some vegetables, than a shark is to blood. No wonder I hate the taste of beets, my nose is probably better than yours.