The field of mycology is lucky to have Organic Chemistry Professor William Wood sniffing the odors of fleshy fungi. Dr. Wood has been the Chemistry Department Chair and a past recipient of the Outstanding Professor of the Year at Humboldt State University (HSU). He is well known at HSU for his lively lecturing style and wide ranging research interests that encompass the odors of wild mushroom, the defensive spray of skunks, and antibiotic compounds.
Recently, Dr. Wood gave a lecture to both the Mycological Society of San Francisco and the Sonoma County Mycological Association that was well illustrated with slides. It covered the importance of fungal odors, odor receptor theory, fungal odor history, the chemistry of mushroom odors and the variability of mushroom odors. The talk concluded with a short presentation of the flavor enhancing ability of some edible mushrooms.
The odors of fungi are important and are used extensively in the literature, in descriptions and in keys to mushrooms. People smell odors because the odor molecule (called the odorant) fits into a molecular receptor in our nose. It turns out that ANY similar chemical fitting into the slot of the receptor will be perceived as a similar smell, even though the chemical is different. DNA research has indicated that we have up to 1,000 different receptors in our nose. Not every person has all of these receptors. Individuals not having a receptor class are "anosmic" to that class of chemicals and cannot detect it. Another problem in human odor perception is "olfactory fatigue" which is caused when a high dose of odorant binds tightly to the receptors and blocks them. When this happens, we cannot detect the odor of further doses of the odorant. In nature, the chemicals responsible for these odors are there for adaptive reasons.... either to attract or repulse another creature.
Dr. Wood's research continues to determine the chemicals responsible for other mushroom odors. He indicated that he hopes to find the chemicals responsible for farinaceous odors and that this odor is best observed from freshly crushed specimens.
He concluded with a discussion of the chemistry and action of flavor enhancers. Many mushrooms contain flavor enhancers such as monosodium glutamate (MSG). This is the same chemical once believed to be responsible for the 'Chinese Restaurant Syndrome'. It is now known that histamines in soy sauce are the real culprit, not MSG. Another flavor enhancer is 5'-guanosine monophosphate (5 'GMP). These chemicals are found in Pleurotus ostreatus, Coprinus comatus and Lentinus edodes. All three of these edibles enhance the flavor of dishes and contribute to the full, balanced taste of a meal.
A few words of caution for mycologists: mushroom odors are best noted in fresh specimens because they can change with time. For some odors, the mushroom must be crushed to release the odor. And finally, when describing a fungal odor; avoid general terms like fruity or fragrant. It is best to connect it to another common smell, such as peppermint or almonds.
Some of the odors discussed during the lecture were:
| Odor | Chemical | Mushroom |
|---|---|---|
| mushroom alcohol | 1-octen-3-ol | common mushroom odor |
| red hots (candy) | methyl cinnamate | Tricholoma magnivelare |
| garlic | lenthionine | Lentinus edodes |
| maraschino cherries | benzyl alcohol | Agaricus augustus |
| truffles | dimethyl sulphide | commercial truffles |
| almond | benzyl aldehyde | Agaricus augustus |
| coumarin | coumarin | Hydnellum suaveolens |
| anise | p-anisaldehyde | Hydnellum suaveolens |
| tooty-fruity | 1,3-imethoxybenzene | Nolanea fructufragrans |
| burnt sugar | o-aminobenzaldehyde | Hebeloma sacchariolens |
| decaying carrion | a mixture of many | Phallus impudicus |
| farinaceous or mealy | unknown | Leucopaxillus amarus |
| cucumber & farinaceous | 2-nonenal | Clitopilus prunulus |