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A complex relationship among chemical concentration, detection threshold and suprathreshold intensity of bitter compounds

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posted on 2007-01-01, 00:00 authored by Russell KeastRussell Keast, J Roper
Detection thresholds and psychophysical curves were established for caffeine, quinine-HCl (QHCl), and propylthiouracil (PROP) in a sample of 33 subjects (28 female mean age 24 ± 4). The mean detection threshold (±standard error) for caffeine, QHCl, and PROP was 1.2 ± 0.12, 0.0083 ± 0.001, and 0.088 ± 0.07 mM, respectively. Pearson product–moment analysis revealed no significant correlations between detection thresholds of the compounds. Psychophysical curves were constructed for each bitter compound over 6 concentrations. There were significant correlations between incremental points of the individual psychophysical curves for QHCl and PROP. Regarding caffeine, there was a specific concentration (6 mM) below and above which the incremental steps in bitterness were correlated. Between compounds, analysis of psychophysical curves revealed no correlations with PROP, but there were significant correlations between the bitterness of caffeine and QHCl at higher concentrations on the psychophysical curve (P < 0.05). Correlation analysis of detection threshold and suprathreshold intensity within a compound revealed a significant correlation between PROP threshold and suprathreshold intensity (r = 0.46–0.4, P < 0.05), a significant negative correlation for QHCl (r = –0.33 to –0.4, P < 0.05), and no correlation for caffeine. The results suggest a complex relationship between chemical concentration, detection threshold, and suprathreshold intensity.

History

Journal

Chemical senses

Volume

32

Pagination

245 - 253

Location

Oxford, England

Open access

  • Yes

ISSN

0379-864X

eISSN

1464-3553

Language

eng

Notes

This is a pre-copy-editing, author-produced PDF of an article accepted for publication by Chemical senses following peer review. The definitive publisher-authenticated version Keast, Russell and Roper, Jessica 2007, A complex relationship among chemical concentration, detection threshold and suprathreshold intensity of bitter compounds, Chemical senses, vol. 32, no. 3, pp. 245-253 is available online at http://dx.doi.org/10.1093/chemse/bjl052

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2007, The Author