Enthalpy-Entropy Compensation and Water Transfer Mechanism in Osmotically Dehydrated Agar Gel.

Enthalpy-entropy compensation and water transfer in osmotically dehydrated agar gel were studied by carrying out experiments at 30, 40, and 50°C in a 60% (w/w) sucrose solution. An additional experiment was carried out at the isokinetic temperature (TB = 14°C) to confirm the physical meaning of TB. When osmotic dehydration (OD) was carried out at the isokinetic temperature, the diffusion coefficient remained constant (≈0.54 × 10-10 m2/s) during the entire process and the weight loss reached a limit (≈0.277 g/g) when the process was performed at TB. Leffler's criterion indicated that diffusion mechanism was entropically controlled given the internal resistance developed during OD. Results were confirmed by the linear relationship found between the relaxation time and entropy variation according to the Adam and Gibbs equation. [ABSTRACT FROM AUTHOR]