Comparison between orthonasal and retronasal flavour perception at different concentrations

Abstract

To be perceived, flavour molecules need to reach the olfactory epithelium, located in the nasal cavity. This can be achieved through orthonasal (sniff) or retronasal (mouth) airways. The intensity perceived will depend on the number of molecules that reach the receptor cells. The aim of this study is to compare the dose-response behaviour of flavour molecules, depending on whether the flavours were sniffed or tasted. Six flavour compounds were studied, including a homologous series of esters, and the differences on dose-response curves (intensity vs. concentration) correlated to the physicochemical characteristics of the flavour molecules. In addition, the matching concentration in water to get the same intensity by sniff as a reference tasted by mouth for some flavour compounds was determined. It was shown that the differences in orthonasal and retronasal perception depend strongly on the physical characteristics of the aroma chemicals.

Tuning to Odor Solubility and Sorption Pattern in Olfactory Epithelial Responses

“…It is likely that these high flow rates, which often occur during olfactory tasks, are more olfactory-relevant flow rates to which the tuning of intrinsic sensitivity is based. This interpretation is supported by the observations of Cenier et al (2013), who do not see substantial differences in response for soluble odorants across the sniff velocities observed in awake animals.…”

“…This pattern can be seen with several glomerular recording techniques (e.g., Johnson et al, 2007). In addition, the steady-state conditions of our study do not account for active sniffing patterns, such as those studied by Cenier et al (2013). However, the interaction of the sorption pattern with the direction and velocity of intranasal airflow can change the sensitivity of response to individual odorants, and should affect the relative concentration of components of complex mixtures in the retronasal versus orthonasal conditions.…”

“…The odor bottles were tested before use to be sure the connections were tight, and a gas chromatograph was used to test whether the concentration and purity remained the same before and after use. The concentrations in oil do not perfectly determine the concentration in air (Cometto-Muñiz et al, 2003). Therefore, it is important to note that the odorants were not matched for effective intensity.…”

“…The contours of the flow patterns in these models correspond to the longitudinal mapping pattern of many receptor genes (Ressler et al, 1993;Vassar et al, 1993;Iwema et al, 2004;Miyamichi et al, 2005). The contours of odorant response also follow that pattern (Scott et al, 1996(Scott et al, , 1997(Scott et al, , 2000(Scott et al, , 2006Scott and Brierley, 1999;Coppola et al, 2013). Recent reviews suggest that this correspondence is driven by the patterns of sorption in the nose that determine the odorant concentration reaching the receptors (Schoenfeld andCleland, 2005, 2006;Scott, 2006;Wachowiak, 2011).…”

“…We chose the logistic equation rather than the Hill equation because they are mathematically equivalent and the logistic equation is easier to fit in the absence of reliable estimates of the maximum response (Barlow and Blake, 1989). The open preparation data were used as a multiplier of the log(odorant concentration) to adjust for the relative stimulus potency in activating olfactory sensory neurons (OSNs).…”