Kinetics of the osmotic hydration of chickpeas

An experiment examining the swelling of chickpeas as they are soaked in water is presented to introduce students to topics such as osmotic flow, mass transfer, diffusion, kinetics of hydration, modeling, and estimation of activation energy. The experiment may be performed by students at home, at the laboratory, or directly by the professor. Experimental data are analyzed using an empirical model (Peleg equation) for the description of moisture sorption curves for different foods soaked in water. The proposed experiment needs inexpensive hardware. The equations that fit adequately with experimental data allow the calculation of initial hydration rates at different temperatures, and subsequently, the estimation of the activation energy, Ea, of the process. The obtained value of Ea (19.5 ± 0.9 kJ/mol) shows a process controlled by diffusion and not by chemical reaction. It was also observed that, for a given temperature, the increase in concentration of NaCl in the immersion solution results in the decrease of hydration kinetics