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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.

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A model of flavor release from encapsulated flavor particles immersed in water has been developed that correlates well with experimental data. Flavor release from particles was determined by measuring both the quantities released from the particle to water and from water to air in the headspace. The model presented here predicts a very different release with time from the encapsulated flavor if the particle develops a hydrogel at the surface (swelling) compared to gradual erosion. Controlled heating showed more retention of flavor when the particle swells compared to a more rapid flavor release under conditions of particle erosion.

The water sorption isotherms are exploited here for maltodextrin-based perfume-delivery systems with the aim of predicting water vapor stability of the samples at a given temperature. A combination of Couchman (glass-transition temperature) and Guggenheim-Anderson-deBoer (GAB) (fraction of water condensed) models is shown demonstrating important information hidden in a simple sorption experiment (rate of loss of perfume by diffusion and capacity to retain volatiles under humid air conditions). Pure maltodextrin and maltodextrin loaded with apolar and polar perfume components are treated using the same developed methodology. It is shown that apolar molecule release from classical carbohydrate spray dry particles follows a zero-order kinetic.

Discretization of a size-exclusion chromatography (SEC) chromatogram is shown here to be an important calculation for characterizing the distribution of a polydisperse polymer, especially when the polydispersity is large. Commercial poly-glucose maltodextrins are known to have such a polydispersity. A mathematical discretization method with Gaussian peaks centered on each individual degree of polymerization is proposed and is performed on the entire SEC chromatogram for three different grades of corn maltodextrins. Because SEC and high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) are based on different separation mechanisms, they can be considered orthogonal techniques, and HPAEC-PAD was therefore used to validate the SEC discretization procedure. Because this validation proved satisfactory for all commercially available oligomers, the discretization is extended to all of their SEC chromatograms. Comparing the number-average molar weight and the weight-average molar weight before and after the mathematical discretization verifies that such a mathematical treatment does not denaturate the chromatogram. This approach tentatively leads to a more exhaustive characterization of a broadly polydisperse sample, such as maltodextrins, than was previously available, as it (i) gets rid of the apparent, chemically irrelevant, continuous molar weight distribution obtained by raw SEC and (ii) addresses the current detection and quantitation limits of the HPAEC-PAD technique without any sample treatment.

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