Influence of temperature and diameter of pale-fleshed, white-skinned spherical sweet potato (Ipomoea batatas) on the mass moisture transport parameters of hot air convection

Abstract

The aim of this study is to the influence of air temperature and samples diameter on the moisture and mas transport parameters for spherical sweet potatoes subjected to drying. In this study, the influence of drying parameters such as air temperature and sample diameter on the mass moisture transport parameters of hot air drying of pale-fleshed, white-skinned spherical sweet potato of ‘BF 13’ variety, (a variety newly introduced and grown in Burkina Faso), were investigated at 50-80°C air temperatures on 2-3 cm diameter samples. Drying experiments were carried out in an air convective oven by measuring the sample weights according to the time. The averages of three replicates were taken as experimental data. As results, the drying coefficient of sweet potato samples increased up to 1.950×10-6 s-1 with increasing drying temperature regardless of the employed sample diameters. At almost all air temperatures, reducing the sweet potato diameters caused the drying coefficient to increase. The increase in air temperature from 50 to 80 °C and decrease in sample diameter from 3 to 2 cm decreased the lag factor from 1.083 to 1.043. The Biot number values decrease from 0.2462 to 0.1232 with increase in the air temperature for all sample diameters. When sample diameter increases, the Biot number values increased regardless of drying air temperature. Moisture diffusivity values increased with increased air temperature from 50°C to 80°C and increased sweet potato sample diameter from 2 cm to 3 cm. The moisture diffusion and convective mass transfer activation energy values were decreased with increasing samples diameter for all drying conditions applied.