Hot air-drying characteristics of pale-fleshed, white-skinned sweet potato spheres (Ipomoea batatas)

Drying of pale-fleshed, white-skinned spherical sweet potato (Ipomoea batatas) (a newly introduced variety grown in Burkina Faso) was carried out at air temperatures of 50°C, 60°C, 70°C, and 80°C using 2 and 3 cm diameter samples to determine its drying characteristics. The results of the analysed drying data indicated that drying occurred during the decreasing rate period. The moisture content of the sample and the drying rate of sweet potato were influenced by the air-drying temperature and the spherical diameter of the samples. The drying time of sweet potato decreased and its drying rate increased with the decrease in the diameter of spherical samples and the increase in air drying temperature. The average effective moisture diffusivity values were obtained in the range of 1.4086 × 10-9 to 3.7214 × 10-9 m2/s and 2.6715 × 10-9 to 6.8775 × 10-9 m2/s for 2 cm diameter samples and 3 cm diameter samples respectively as temperatures increased from 50 °C to 80 °C. This dependence allowed the determination of the activation energy values of 2 and 3 cm diameter sweet potato samples which were found to be 30.50 and 27.71 kJ/mol, respectively.