The design of the artificial throat was inspired on the hypothesis that the majority of aroma release from liquids in vivo originates from the layer that remains at the inner surface of the human throat after swallowing (Weel et al. 2003a). The results obtained with the equipment are in line with this hypothesis (Weel et al. 2004b). With respect to the sample volume, the amount of liquid that remains on the surface is only slightly dependent on the amount of liquid passing through, as long as the total amount is much larger than the amount constituting the film at the inner surface. When the aroma concentration is higher, there is proportionally more aroma compound available for release as expected. At equilibrium conditions a higher temperature leads to a stronger partitioning of volatiles into the air phase. This has been demonstrated previously for a range of aroma compounds (Roberts and Acree 1995, Deibler and Acree 1999). However, the sample temperature does not influence the total aroma release, neither in vivo nor in the artificial throat, because all aroma present in the thin film will rapidly release, once the exhalation or airflow starts. A decrease in measured release with increasing flow rate is also expected, because only a part of the air exhaled either by the artificial throat or the panellists, is sampled. The aroma concentration is determined in the part of the air sampled. When the flow rate is higher, the aroma compounds are more diluted, resulting in a lower concentration. The total released amount of aroma does not change within the range of flow rates studied, because all aroma compounds present will release. The decrease in peak width at higher flow rate indicates that the reservoir of aroma molecules present in the thin liquid film (coating the inner surface of both the human throat and the artificial throat) is exhausted faster.
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