Determination of aroma compound diffusion in model food systems: Comparison of macroscopic and microscopic methodologies Original Research Article

Diffusion properties at macroscopic and microscopic scales for three aroma compounds (in solution and gel systems) were characterized using three different methodologies: the diffusion cell and the Volatile Air Stripping Kinetic methods for the determination of apparent diffusion coefficients and the pulsed-field-gradient Nuclear Magnetic Resonance method for the determination of self-diffusion coefficients. The accuracy of the methods was established by comparing ethyl hexanoate diffusion coefficient in water or D2O solution and in 1%-agar gel system at 25 and 30 °C. The robustness of the three methodologies was also investigated in 1%-iota-carrageenan system with different NaCl content leading to gel strengthening. In 1%-agar gel as well as in 1%-iota-carrageenan systems, the apparent or self-diffusion coefficients of aroma compounds had the same order of magnitude regardless of the approach, ranging between 2.3 × 10−10 and 10.4 × 10−10 m2 s−1. Diffusion properties were discussed in terms of the different observation scales (diffusion scales) and of the nature of gel network.