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.

An extruding machine for the production of floating fish feed was designed and fabricated. Performance evaluation of the fabricated floating fish feed extruding machine was done. The design of the hopper; shaft, barrel, screw and die of the machine were done using standard equations. Effect of extrusion parameters which are moisture content (20% 25%, 30%, 35%, and 40%) die size (2 mm, 4 mm, 6 mm, 8 mm and 10 mm) and screw speed (150 rpm; 200 rpm, 250 rpm, 300 rpm and 350 rpm) on expansion ratio, floatability, specific mechanical energy and efficiency were evaluated. The result shows that moisture content has significant effect on all the variables, as highest expansion ratio of 32% was obtained at 30% moisture content and 6 mm die size. Highest feed floatability was 97% at 30% moisture content and 6 mm die size. The highest specific mechanical energy of the machine was 30 kJ/kg at 40% moisture content and 4 mm die size. Die size variation also shows high impact on the machine performance, showing highest efficiency of 83% at 10 mm die size and 250 rpm while the floatation rate was 98% at 6mm die size. Screw speed has significant effect on efficiency having the highest as 85% at 150 rpm and floatability of 93% at 150 rpm while the specific mechanical energy of 29 kJ/kg was the highest at 350 rpm. Operation condition was at its best at 30% moisture content; 6 mm die size and 150 rpm of screw speed. The feed moisture content, machine die size and screw speed have significant effect on the performance of the machine. Careful selection and combination of these factors will give optimum performance of the machine during extrusion of resin.

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Introduction: Foam mat drying involves the change of agricultural material from a high moisture content level to a stable foam which is achieved by moisture reduction mechanism. Aim: In this study, foam-mat drying process of watermelon was optimized using response surface methodology. Foaming conditions (carboxyl methyl cellulose and egg albumen) and the drying system parameters (air velocity and air temperature) were optimized using response surface methodology. Methodology: To evaluate the drying behaviour, the drying experiment was designed using design expert software using a central composite design setting variable of drying temperature (60°C – 80°C), air velocity (0.5 m/s – 2 m/s), carboxyl methyl cellulose (0.5% - 2.5%), egg albumen (5% - 15%). Twenty-two runs of the experiment were performed using different levels of variables combinations. Based on the statistical tests performed, the best model that described each response was selected using a polynomial analysis. Results: The optimum values for the drying conditions were: 77.42OC, 0.5m/s, 0.5% and 5% for temperature, air velocity, carboxyl methylcellulose and egg albumen respectively and the optimum values for the drying characteristics were: 25.07 KJ/mol, 1.7345E-10 m2/s, 29.019% (wet-basis). 0.742 g/cm3 and 540 minutes (approximately 9hrs) for activation energy, effective diffusivity, moisture content, foam density and the drying time respectively. Conclusion: The study of the foam-mat drying of watermelon pulp revealed that the inlet temperature, air velocity, CMC and egg albumen has a significant effect on its drying characteristics.

This research is concerned with the energy performance analysis of convective drying of sorghum gruel residue. The process was carried out on a hot air dryer conducted at four drying air temperatures of 40, 50, 60, and 70 °C respectively, three different air velocities 0.8, 1.0 and 1.2m/s and three different varieties of sorghum gruel residue, Caudatum,Durra and Guineense respectively. The effects of drying temperature and air velocities on the specific energy consumption, energy efficiency, drying efficiency and thermal efficiency were investigated. The specific energy consumption for Caudatum,Durra, Guineensevarieties ranges from 169530.001 J/kg - 71433.758 J/kg, 170557.25 J/kg - 76732.96 J/kg and 179367.266 J/kg - 83750.923 J/kg respectively while the energy efficiency for Caudatum,Durra, Guineensevarieties ranges from 35.5% - 13.934%, 31.188% - 13.836% and 28.463% - 13.157% respectively. The results of this study also confirmed that the convective drying process is energy intensive and drying fresh agricultural produce with heated-air dryers requires a relatively large amount of energy.