Kinetic, thermodynamic properties, and optimization of barley hydration

The hydration kinetics of five barley cultivars was studied at six different temperatures ranging from 10 to 35 degrees C for 32 hours applying the Peleg model. Response Surface was used to describe dynamic of the process and identify the hydration time for each cultivar. The activation energy (E-a), enthalpy (Delta H*), entropy (Delta S*), and Gibbs free energy (Delta G*) were estimated from the adjusted parameters and Arrhenius equation. Temperature had significant effect on the hydration of the five cultivars. At low temperatures, the stabilization time for hydration was faster. Peleg constants K-1 and K-2 decreased with increasing temperature. The cultivar BRS BRAU showed the lowest value of initial absorption rate (R-0 = 0.149 kg.h(-1)) at 10 degrees C, while the cultivar BRS BOREMA had the highest value of R-0 (0.367 kg.h(-1) at 35 degrees C). The equilibrium moisture content (M-e) increased with increasing temperature. The cultivars BRS CAUE and BRS BRAU showed the lowest values of E-a, Delta H*, Delta S* showed negative values, and Delta G* increased with increasing temperature, confirming the effect of temperature on hydration.