Odor detection of mixtures of homologous carboxylic acids and coffee aroma compounds by humans.
Mixture summation among homologous carboxylic acids, that is, the relationship between detection probabilities for mixtures and detection probabilities for their unmixed components, varies with similarity in carbon-chain length. The current study examined detection of acetic, butyric, hexanoic, and octanoic acids mixed with three other model odorants that differ greatly from the acids in both structure and odor character, namely, 2-hydroxy-3-methylcyclopent-2-en-1-one, furan-2-ylmethanethiol, and (3-methyl-3-sulfanylbutyl) acetate. Psychometric functions were measured for both single compounds and binary mixtures (2 of 5, forced-choice method). An air dilution olfactometer delivered stimuli, with vapor-phase calibration using gas chromatography-mass spectrometry. Across the three odorants that differed from the acids, acetic and butyric acid showed approximately additive (or perhaps even supra-additive) summation at low perithreshold concentrations, but subadditive interactions at high perithreshold concentrations. In contrast, the medium-chain acids showed subadditive interactions across a wide range of concentrations. Thus, carbon-chain length appears to influence not only summation with other carboxylic acids but also summation with at least some unrelated compounds.
Miyazawa
Toshio
T
Monell Chemical Senses Center, 3500 Market Street, Philadelphia, Pennsylvania 19104, USA.
Gallagher
Michele
M
Preti
George
G
Wise
Paul M
PM
D000328:Adult; D002264:Carboxylic Acids / Q000032:analysis*; D003069:Coffee / Q000737:chemistry*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009812:Odorants / Q000032:analysis*; D012903:Smell; D014835:Volatilization; D055815:Young Adult
D002264:Carboxylic Acids; D003069:Coffee