Hydration kinetics of red kidney beans (Phaseolus vulgaris L)

Soaking of dry red kidney beans was studied at 20, 30 40 and 60 degrees C by the method of weight gain until equilibrium conditions were attained. Water absorbed during soaking was a function of both soaking time and temperature. Soaking at high temperatures increased the hydration rate constant and decreased soaking time to achieve equilibrium. Compared to unblanched beans, the application of a pre-blanching step considerably reduced hydration times of blanched beans. Due to the plasticity effect acquired upon blanching, blanched beans showed a significantly high hydration rate constant and exhibited a more constant equilibrium moisture content regardless of soaking temperature. Activation energy values (E-a) of the hydration process were 6.48 Kcal/mole for blanched and 14.25 for unblanched beans.