Assessment of Ethanol and Isoamyl Acetate Interactions in Odor Perception

Ethanol is a major component of wine and spirits, contributing as a solvent and through its own odor, yet in olfactometry, it is usually treated as a passive background, its gas-phase concentration inferred from the liquid. A forced-evaporation olfactometer was developed to deliver gas-phase ethanol concentrations calculated by mass balance; electrochemical sensors verified its output up to about 1000 ppm (r2 = 0.9942). Two panels were used: a glass panel (n = 35) rated 11 ethanol solutions (0.5 to 50% v/v) and an olfactometer panel (n = 19) rated gas-phase ethanol; On a common gas-phase axis, four-parameter log-logistic fits gave ED50 values of 13,772 ppm (glass, calculated) and 1779 ppm (olfactometer, mass-balanced). Panel and modality are confounded, so this 7.7-fold separation cannot directly be assigned to the dilution at the nose, although its direction is consistent with such dilution. In addition, a 3 × 3 within-subject design crossed isoamyl acetate nominal concentrations with ethanol gas-phase concentration. Acetate ratings were highest at the intermediate and lowest at the highest ethanol level, with no significant dependence on acetate concentration; as ethanol level was confounded with presentation order, this pattern is exploratory.