Effects of air flow-rate on flavour release from liquid emulsions in the mouth

The penetration theory of interfacial mass transfer was used to model dynamic flavour release from liquid emulsions in the mouth. The gas phase was efficiently stirred by the introduction of gas flows (10-200 mL min(-1)) through the headspace, which also simulated breathing and the transport of flavour molecules from the oral cavity to the olfactory epithelium. The model was used to predict the time-dependent release profiles of two volatiles, one hydrophilic (diacetyl) and the other hydrophobic (heptan-2-one), as a function of the oil volume fraction. Expressions for the maximum flavour intensity and time to reach the maximum flavour intensity were obtained. In general the initial rates of release were faster for emulsions of lower oil content. The maximum flavour intensity was found to be linearly proportional to the initial flavour concentration, whereas the time to reach the maximum flavour intensity was independent of the initial flavour concentration.