Objective Assessment of the Influence of Low Impact Odorants in Mixtures Via Model Neurological Studies

Abstract

Low impact odorants are generally considered unimportant in aroma perception, however there is evidence that suggests such compounds are significant in global odour perception (e.g. Escudero et. al. 2004). Gas Chromatography-Olfactometry (GC-O) is commonly used for the analysis of odour extracts; however low impact odorants cannot be detected at the olfactory sniff port. ‘Reconstruction discrepancy’ (Bult et al. 2001) describes the phenomenon that the perceived smell of GC-O reconstructed mixtures differ from that of the original aroma of the whole sample, despite the fact that concentrations of the key odorants are identical in both mixtures. The purpose of the present study was to objectively assess how low impact odorants modify the perception of the high impact odorants in an odour mixture through sensory and neurological model studies (Ryan et al. 2008). The participants included six male staff of Charles Sturt University. In order to continually monitor brain activity, participants were connected to a 64 channel electroencephalogram (EEG) while they were exposed to three aroma treatment conditions. Participants were then asked to report on their perceptions. A combination of the two allowed comparison between subjective self-report responses and objective neurological responses to the aromas. The three aroma treatment conditions were: 1) isoamyl acetate (fruity), 2) whiskey lactone (woody), and 3) isoamyl acetate with a sub-threshold level of whiskey lactone (altered fruity). Within each treatment condition, differences were observed between the EEG responses to the odourant and the EEG responses to an odourless control stimulus. Additionally, differences were observed between the EEG responses to ‘fruity’ and ‘altered fruity’ conditions in the frontal and left temporoparietal scalp regions. Further, differences in EEG responses to ‘woody’ and ‘altered fruity’ conditions were also observed in the occipital scalp region. The participants’ self-report responses will be discussed within the paper in relation to the EEG responses.

Reference

Ryan, D., Thomas, J. B., Dubaj, M., Patterson, J., Prenzler, P. D., & Saliba, A. J. (2011). Objective Assessment of the Influence of Low Impact Odorants in Mixtures Via Model Neurological Studies. 9th Pangborn Sensory Science Symposium, 4–8 September. Toronto, Canada. (Poster)

Links

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