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A series of three experiments investigated the nature of metallic taste reports after stimulation with solutions of metal salts and after stimulation with metals and electric currents. To stimulate with electricity, a device was fabricated consisting of a small battery affixed to a plastic handle with the anode side exposed for placement on the tongue or oral tissues. Intensity of taste from metals and batteries was dependent upon the voltage and was more robust in areas dense in fungiform papillae. Metallic taste was reported from stimulation with ferrous sulfate solutions, from metals and from electric stimuli. However, reports of metallic taste were more frequent when the word 'metallic' was presented embedded in a list of choices, as opposed to simple free-choice labeling. Intensity decreased for ferrous sulfate when the nose was occluded, consistent with a decrease in retronasal smell, as previously reported. Intensity of taste evoked by copper metal, bimetallic stimuli (zinc/copper) or small batteries (1.5-3 V) was not affected by nasal occlusion. This difference suggests two distinct mechanisms for evocation of metallic taste reports, one dependent upon retronasal smell and a second mediated by oral chemoreceptors.

1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN) is well-known to contribute "petrol" aromas to aged Riesling wines, but its prevalence and contribution to young Riesling or non-Riesling wines is not well understood. TDN concentrations were measured in 1-3-year-old varietal wines produced from Cabernet franc (n = 14 wines), Chardonnay (17), Cabernet Sauvignon (4), Gewurztraminer (4), Merlot (9), Pinot gris (6), Pinot noir (9), Riesling (28), or Sauvignon blanc (6). TDN concentrations in the Riesling wines, 6.4 ± 3.8 μg/L, were significantly higher than in all other varietals, 1.3 ± 0.8 μg/L. The odor detection thresholds for TDN were then determined in both model wine and a neutral white wine. Group sensory thresholds were found to be the same in both matrices, 2 μg/L, indicating little masking of TDN due to the odorants in the neutral white. The TDN sensory threshold was a factor of 10 below the previously reported odor threshold. On the basis of this revised threshold, 27 of 28 Riesling wines had suprathreshold TDN, whereas only 7 of 69 non-Riesling wines had suprathreshold TDN. The monoterpenes linalool and geraniol were also measured in the Riesling wines, and odor activity values (OAVs) were calculated for the monoterpenes and TDN. The OAV for TDN was higher than for the monoterpenes in 25 of 28 Riesling wines.

Hexanal (C6) and octanal (C8) exhibit two different odor qualities at all concentrations: C6 is perceived as green, while C8 is perceived as citrus. This paper examines the odor perception (quality+intensity) of C6-C8 binary mixtures by varying the concentration ratios within the mixtures and using an odor reference-matching task to estimate perceived intensity. Three perceptible concentrations of C6 and C8, low (L), medium (M), and high (H), were prepared. Subjects were trained to match the quality and intensity of blind samples of these standards with their appropriate reference. Mixtures were composed of a focal or "figure" odorant (indicated below in bold) of the same odor quality as the references and a second odorant defined as the "ground" odorant. In subsequent sessions, subjects were asked to evaluate their perception of the quality of the focal odorant in a C6-C8 mixture. Stimuli for C6 matching tasks, where C6 was both the reference and the figure, were: 6L-8M, 6M-8L, 6M-8M, 6M-8H, and 6H-8M. The C8 matching tasks were the same, except that the roles of C6 and C8 were reversed. When the figure odorant was stronger than or iso-intense to the ground odorant, mixtures were often matched to a less intense reference, indicating suppression (compensation) of the figure by the ground odorant.

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