Hydration Kinetics of Lupin (Lupinus Albus) Seeds

The hydration kinetics of lupin (Lupinus albus) seeds was studied by soaking in water at temperatures of 20, 30, 40 and 50C (±1C) in constant‐temperature water bath for 9 to 12 h. The weight gain due to the hydration process was determined in terms of moisture content (% dry basis). Water absorption rate was high at the early stage of hydration (20–60 min depending on temperature) followed by a decreased rate and finally approaching equilibrium condition. Peleg's equation adequately described the hydration characteristics of lupin seeds under the experimental condition (R2 = 0.96 to 0.99). The Peleg rate constant k1 decreased from 2.537 to 0.241 min/%, while Peleg capacity constant k2 increased from 0.0036 to 0.0070/% significantly (P < 0.05) with an increase in temperature from 20 to 50C, demonstrating that the water absorption rate increased and water absorption capacity decreased with increase in temperature. The temperature dependence of k1 and k2 was described by Arrhenius type equation with R2 values of 0.98 and 0.97, respectively, and activation energy of 60.44 kJ/mol. The agreement between experimental and estimated values of the hydration data (R2 = 0.97 to 0.99) confirmed that Peleg's equation could be used to describe the hydration characteristics of lupin seeds under the experimental conditions considered.