  After swallowing a liquid or a semi-liquid food product, a thin film
responsible for the dynamic profile of aroma release coats the pharyngeal
mucosa. The objective of the present article was to understand and quantify
physical mechanisms explaining pharyngeal mucosa coating. An elastohydrodynamic
model of swallowing was developed for Newtonian liquids that focused on the
most occluded region of the pharyngeal peristaltic wave. The model took
lubrication by a saliva film and mucosa deformability into account. Food bolus
flow rate and generated load were predicted as functions of three dimensionless
variables: the dimensionless saliva flow rate, the viscosity ratio between
saliva and the food bolus, and the elasticity number. Considering physiological
conditions, the results were applied to predict aroma release kinetics. Two
sets of conditions were distinguished. The first one was obtained when the
saliva film is thin, in which case food bolus viscosity has a strong impact on
mucosa coating and on flavour release. More importantly, we demonstrated the
existence of a second set of conditions. It was obtained when the saliva film
is thick and the food bolus coating the mucosa is very diluted by saliva during
the swallowing process and the impact of its viscosity on flavour release is
weak. This last phenomenon explains physically in vivo observations for
Newtonian food products found in the literature. Moreover, in this case, the
predicted thickness of the mix of food bolus with saliva coating the mucosa is
approximately of 20 $\mu$m; value in agreement with orders of magnitude found
in the literature.
