Flavor encapsulation in yeasts: limonene used as a model system for characterization of the release mechanism

Empty yeast cells are used as a new delivery system for flavor encapsulation. The flavor release mechanism from yeast cells is characterized using a series of analytical techniques, and limonene is used as a model representing a hydrophobic flavor. Furthermore, the thermal stability of the capsules was assessed. The characterization of the cell wall structure gives rise to the development of an empirical model explaining water adsorption as well as the desorption singularities observed on drying. The study of the rate of flavor release as a function of temperature and water uptake in the cell wall clearly demonstrated a particular behavior of the yeast cell wall permeability. Below a water activity around 0.7, no flavor release is permitted whereas release occurs above it. Surface analysis on dry or wet cells using atomic force microscopy is discussed.