Authors: Lugaz, O.¹; Pillias, A.-M.¹; Boireau-Ducept, N.²; Faurion, A.¹

Source: Chemical Senses, Volume 30, Number 1, January 2005 , pp. 89-103(15)

Publisher: Oxford University Press

Abstract:

The role of the chemical properties of sour stimuli and the role of the human saliva flow rate on acid perception were investigated in 11 high saliva flow rate (HF) and 11 low saliva flow rate (LF) subjects with a continuous stimulus delivery flow rate of 3.2 ml/min and using the time–intensity technique for perception recording. Continuously measuring the pH on the tongue surface on three HF and three LF subjects showed that HF subjects' saliva decreased the acidity of the acid solution more efficiently than the LF subjects' saliva did. However, HF subjects exhibited higher perceived intensity for acid solutions than LF subjects. At equal pH, the order of the efficiency of acids indicated that HCl was the least efficient acid stimulus and acetic acid the most efficient. At equal concentration, the order of efficiency was the opposite (citric acid > malic acid > lactic acid > acetic acid), indicating that titratable acidity rather than pH has to be considered when comparing weak acids. At high concentrations, the ratio of relative efficiency is more in favor of the hydrophobic than the hydrophilic acid in HF subjects compared with LF subjects, i.e. HF subjects are more sensitive to hydrophobic stimuli. Hydrophobic molecules may diffuse more easily into the epithelium of HF than LF subjects, and reach more efficiently trigeminal nerve endings in addition to taste receptor cells.

Keywords: acids; human; lingual pH; saliva; time–intensity

Document Type: Research article

DOI: http://dx.doi.org/10.1093/chemse/bji004

Affiliations: 1: Laboratoire de Neurobiologie Sensorielle, Unité Neurobiologie de l'Olfaction et de la Prise Alimentaire, INRA, Domaine de Vilvert, Bât. 325, 78352 Jouy en Josas, France and 2: Danone Vitapole, RD 128, 91767 Palaiseau cedex, France

Publication date: 2005-01-01

More about this publication?

• Chemical Senses publishes original research and review papers on all aspects of chemoreception in both humans and animals. An important part of the journal's coverage is devoted to techniques and the development and application of new methods for investigating chemoreception and chemosensory structures.

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