Modelling of hydration kinetics of brown and grey African yam bean varieties using Peleg’s Equation

Abstract

Application of the Peleg model was investigated for predicting hydration kinetics of brown and grey African Yam bean seed (AYB) varieties during soaking in water at temperatures 30, 40, 50 and 60^oC in constant-temperature water bath for 0.5 – 12 h. Peleg’s model was found to describe the hydration process of AYB seeds adequately under the experimental condition. Brown and grey AYB seeds showed no significant difference (p > 0.05) in the Peleg rate constant (K₁) and Peleg capacity constant (K₂) within and between the experimental conditions. The Peleg constant (K₁) decreased from 6.66 x 10^-2 to 1.5 x 10^-2 h %^-1 for the grey AYB, and from 4.89 x 10^-2 to 1.21 x 10^-2 h %^-1 for the brown AYB seeds as the hydration temperature increased from 30 to 60^oC, suggesting a corresponding increase in the initial water absorption rate. The temperature dependence of K₁ was described using Arrhenius equation. The activation energy (Ea) for brown and grey AYB seeds were 32.20 and 48.70 KJ/mol respectively. The Peleg capacity constant (K₂) for brown and grey AYB varieties decreased from 1.04 x 10^-2 to 8.70 x 10^-3%^-1 and from 8.40 x 10^-3 to 7.80 x 10^-3%^-1, respectively with increasing temperature, from 30 to 60^oC, indicating that the water absorption capacity increased with increase in temperature. The lower value of Ea for the brown variety indicates that the seeds were more thermally stable and hydration changes were less influenced by temperature.

Keywords: African yam bean seeds, water absorption, Peleg model, temperature, activation energy