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Introduction: The hydration of grains is a process that consists of soaking them in water in order to increase their moisture content and this is a crucial step in industrialized processing and provides several beneficial effects on their physicochemical and nutritional qualities.
Aims: This study focused on modeling of hydration characteristics of five varieties of cowpea which are: Gombe, Oloyin white, Drum, Oloyin brown and Sokoto cultivated in Nigeria.
Methodology: The experiments were carried out using electronic water bath at five temperatures (30, 40, 50, 60, and 70°C) in three replications. The amount of water absorption by five selected varieties of cowpea grains was calculated by measuring the increase in the mass of soaked grains per time. Five standard models of water absorption were fitted to the experimental data. Coefficient of determination (R2), chi-square (x2) and root mean square error (RMSE) were used to evaluate the models.
Results: The initial moisture content of the saturated cowpea was estimated as 13.56 ±1.15, 15.05 ±2.27, 13.30 ±0.37, 10.85 ±0.13, 12.40 ±0.13 for Gombe, Oloyin white, Drum, Oloyin brown and Sokoto varieties respectively. The water uptake of the cowpea was faster at the initial stage and gradually slow down until the equilibrium moisture content was attained for all the varieties.
Conclusions: Weibull model was adjudged as the best fitted model for describing the water absorption property of all the varieties of the cowpea and the Activation energy of Gombe, Oloyin white, Drum, Oloyin brown and Sokoto varieties are 42.26 ± 4.65, 40.36 ±8.90, 39.47 ±8.62, 43.08 ±5.25 and 39.66 ±6.72 respectively.