Model Studies on the Release of Aroma Compounds from Structured and Nonstructured Oil Systems Using Proton-Transfer Reaction Mass Spectrometry

Relative retention, volatility, and temporal release of volatile compounds taken from aldehyde, ester, and alcohol chemical classes were studied at 70 °C in model systems using equilibrium static headspace analysis and real time dynamic headspace analysis. These systems were medium-chain triglycerides (MCT), sunflower oil, and two structured systems, i.e., water-in-oil emulsion and L2 phase (water-in-oil microemulsion). Hydrophilic domains of the emulsion type media retained specifically the hydrophilic compounds and alcohols. Four kinetic parameters characterizing the concentration- and time-dependent releases were extracted from the aroma release curves. Most of the kinetic parameter values were higher in structured systems than in oils particularly when using MCT. The oil nature was found to better control the dynamic release profiles than the system structures. The release parameters were well-related (i) to the volatile hydrophobicity as a function of the oil used and (ii) to the retention data in the specific case of the L2 phase due to a specific release behavior of alcohols. Keywords: Proton-transfer reaction mass spectrometry; L2 phase; water-in-oil emulsion; partition coefficient; aroma retention; dynamic aroma release