TITLE:
Effect of Soaking Temperature on Water Absorption Characteristics of Selected Ghanaian Cowpea Varieties
AUTHORS:
Nancy Nelly Idun-Acquah, Ahmad Addo, Ato Bart-Plange
KEYWORDS:
Cowpea, Water Absorption, Diffusion Coefficient, Arrhenius-Type Equation, Modelling
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.9 No.9,
September
26,
2019
ABSTRACT: The
water absorption kinetics of three cowpea varieties (Asontem, Hewale and Asomdwee) was studied following the phenomenological models derived from Fick’s
law of diffusion. Soaking of seeds from each cowpea variety was carried out for
10 h at four temperatures (30°C, 40°C, 50°C and 60°C). The saturation moisture content was higher for Asontem (106.9 g
water/1000 g dry
weight) and Hewale varieties (108.7 g water/1000 g dry
weight) and lower for Asomdwee hybrid (100.7 g water/1000 g dry weight),
respectively. The proposed Fick’s law of diffusion satisfactorily described the
kinetics of water absorption regardless of the variety and temperature. The
estimated values for water diffusion
coefficient for Asontem, Hewale and
Asomdwee varied from 5.12 × 10-10 m2/s to 6.64 × 10-10 m2/s, 3.96 × 10-10 m2/s to 5.12 × 10-10 m2/s, 4.93 × 10-10 m2/s to 6.08 × 10-10 m2/s, respectively. The strong influence of temperature on the water
diffusion coefficient was adequately described by an Arrhenius-type
equation with activation energy values for Asontem, Hewale and Asomdwee as 7.27 kJ/mol, 7.26 kJ/mol and 6.26 kJ/mol, respectively.