Christian Milo

Effects of Cross-Linking, Capsule Wall Thickness, and Compound Hydrophobicity on Aroma Release from Complex Coacervate Microcapsules

Microcapsules were produced by complex coacervation with a gelatin-gum acacia wall and medium-chain-triglyceride core. Dry capsules were partially rehydrated and then loaded with model aroma compounds covering a range of volatility, hydrophobicity, and molecular structure. An experimental design was prepared to evaluate the effects of cross-linking, wall/core ratio, and volatile load level on aroma release from capsules in a hot, aqueous environment. The real-time release on rehydration was measured by monitoring the headspace of a vessel containing the capsules to proton transfer reaction mass spectrometry (PTR-MS). Data collected showed no effects of cross-linking or wall/core ratio on volatile release in hot water for any of the volatiles studied. When comparing real-time release of the prepared coacervates to a spray-dried equivalent, there was no difference in the release from hot water but the release was slower when coacervates were added to ambient-temperature water. We found volatile release to be primarily determined by compound partition coefficients (oil/water and water/air) and temperature.

Quantification of Aroma-Impact Components by Isotope Dilution Assay—Recent Developments

The principle of isotope dilution assay (IDA) was first reported by Rittenberg & Foster (1940) for the analysis of fatty acids and amino acids in complex mixtures. Sweely and coworkers (1966) used deuterated glucose for the determination of glucose in plant tissues. IDA has been proposed as a reference method in clinical chemistry (Bjorkhem et al., 1976). The theoretical basis of IDA was established by Pickup and McPherson (1976). De Bievre (1990) and Sabot (1994) have recently published reviews on this technique.