Physicochemical Properties and Hydration Kinetics of Kenaf (Hibiscus cannabinus) Seed

Abstract

Hydration of kenaf seed was studied at 25, 35 45, 55 and 65 °C by the method of weight gain until equilibrium was achieved along with the physicochemical properties of the seed. The results showed that the kenaf seed had a small dimension and brownish surface color. Water absorbed during soaking was a function of soaking time and temperature. Soaking at higher temperatures increased the hydration rate constant and decreased the soaking time needed to reach equilibrium. Sigmoidal, Peleg and Page models effectively described the hydration characteristics of the seed under the soaking temperatures. The half-saturation time; τ, Peleg' s rate constant; K₁ and Page rate constant K₃ decreased from 199.78-32.97 min, 2.55-0.47 min/% and 3.14-2.74 min/%, respectively, while the sigmoidal rate constant; K increased from 0.85-6.83 min^-1 with an increase in soaking temperature from 25-65 °C. The rate of water absorption of the seed at a higher temperature was faster. The temperature dependence of K was explained by the Arrhenius equation, from which activation energy of 71.31 KJ/mol was obtained.