Determination of aroma compound diffusion in model food systems: comparison of macroscopic and microscopic methodologies
Résumé
Diffusion properties at macroscopic and microscopic scales for 3 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 the 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 gels, 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.