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.

Fatty acid, amino acid composition and effects of soaking temperatures on physicochemical qualities of <i>Hibiscus cannabinus</i> seed extract

“…The kenaf seed extracts for the seeds soaked at 25 and 35 o C had significantly higher ash content (0.59 and 0.54 %, respectively) than the kenaf seed extracts of the seeds soaked at 45, 55 and 65 o C. This variation is due to the slower rate of water absorption at lower temperature as observed in our earlier studies (Ibrahim et al, 2022). The ash content (2.46 % and 1.88 %) reported for corn milk and breadfruit extracts, respectively (Ifediba and Nwabueze, 2018) were higher than the ash content found for the kenaf seed extracts for the different soaking temperatures of the seed.…”

“…The aliquot was filtered using a 0.22 µm membrane filter into a vial. These might be because optimum moisture content is often achieved between temperature 47 °C to 67 °C as observed in our earlier studies (Ibrahim et al, 2022). Likewise, higher temperature has been observed to damage cell membrane of seeds, causing the seeds to edge and rapidly absorb water.…”