(R)-(-)-2-methylisoborneol - described as musty, mold-like, earthy by Blank & Grosch; also as camphoraceous, rubbery (by Tyler) Odor threshold: 0.006-0.012 ng/liter (air) Odor threshold (orthonasal): 20-30 ng/liter (water) Odor threshold (retronasal): 5-10 ng/liter (water) = (1R,2R,4R)-1,2,7,7-tetramethylbicyclo[2.2.1]heptan-2-ol Per-Edvin Persson has discussed the odor differences (i.e. musty vs camphoraceous) and noted that that odor characterization of compounds in the pure state (e.g. Tyler) may not be relevant for situations where these compounds appear as trace contaminants (i.e., diluted), exhibiting different odor characteristics, as is the case for 2-methylisoborneol in natural waters. Ref: D. Tyler, et. al., J. Agric. Food Chem., 26, 1415- 1417(1978); Mans H. Boelens, Harrie Boelens & Leo J. van Gemert, Perfumer & Flavorist, Vol. 18, No. 6, 1-15, 1993; Imre Blank & Werner Grosch, On the Role of (-)-2-Methylisoborneol for the Aroma of Robusta Coffee, J. Agric. Food Chem. 2002, 50, 4653-4656; Per Edvin Persson, The odor of 2-methylisoborneol, J. Agric. Food Chem., 1980, 28 (6), p 1344

(S)-(+)-2-methylisoborneol - camphoraceous, rubbery (Tyler) = (1S,2S,4S)-1,2,7,7-tetramethylbicyclo[2.2.1]heptan-2-ol It is generally accepted that 2-methylisoborneol in dilution is responsible for musty, moldy, earthy off-tastes in water and other products (e.g., catfish). Ref: D. Tyler, et. al., J. Agric. Food Chem., 26, 1415- 1417(1978); Mans H. Boelens, Harrie Boelens & Leo J. van Gemert, Perfumer & Flavorist, Vol. 18, No. 6, 1-15, 1993; Imre Blank & Werner Grosch, On the Role of (-)-2-Methylisoborneol for the Aroma of Robusta Coffee, J. Agric. Food Chem. 2002, 50, 4653-4656; Per Edvin Persson, The odor of 2-methylisoborneol, J. Agric. Food Chem., 1980, 28 (6), p 1344

Ionones, Irones, Damascones & Structurally Related Odorants

Acyclics (Alcohols, Esters, Acids, Aldehydes)

Lactones

Sesquiterpenoid Related Odorants