A mathematical model of volatile release in mouth from the dispersion of gelled emulsion particles

This paper presents a mathematical model of in-mouth volatile release from gelled emulsion particles dispersed in a continuous aqueous phase. Data based on APCI MS-Breath analysis is presented to demonstrate the effect of particle size, oil content and oil-water partition coefficients. It is shown that in-mouth release of aroma from the dispersion of gelled emulsion particles follows a two-component kinetic equation with fast and slow components. Both the fast and slow rate constants depend on the particle size, oil content and oil water partition coefficient of the aroma. The relative amount of aroma contributing to the fast and slow components also depends on the size of the particles. In order to understand this unexpected behaviour, an analytical model was developed that considers the interplay between the mass transfer of flavour across the interface of the particles and that across the air-liquid interface. Analytical expressions for the two rate constants and the relative ratio of aroma contributing to the fast component have been derived. From this model, three regimes of in-mouth release of aroma from the dispersion of gelled emulsion particles were identified including, the emulsion regime, the transition regime and the gel particle regime. In the emulsion regime, changes in the size of gelled emulsion particles had negligible impact on the overall release. In the transition regime, the release was controlled by the interaction of flavour transfer from the particles with that across the air-water interface. In the gel particle regime, aroma release at long times was governed by the particles and that at short times was governed by the air-water interface, and the two processes were fully decoupled. A simple relationship was derived for the critical size above which the release of aroma from the dispersion of gelled emulsion particles is affected by the size of the particles.