Characterization of Thin Layer Hot Air Drying of Sweet Potatoes (I pomoea batatas L.) Slices

Abstract

The effect of drying temperature (50, 60, 70 and 90C) and sample thickness (0.3, 0.4, 0.6 and 0.8 cm) on characterization of hot air drying of sweet potato slices were investigated. Results indicated that drying took place in the falling rate period. The average values of effective moisture diffusivities of sweet potato slices ranged from 3.66 × 10−10 to 2.11 × 10−9 m2/s within the given drying temperature range. The average activation energy values were 13.48–16.50 kJ/mol for sample thickness of 0.3–0.8 cm. Twelve thin layer drying models were fitted using experimental drying data. The goodness of fit for models was evaluated using the values of coefficient of determination (R2), root mean square error, chi-square (χ2) and mean relative percent deviation (P). Results showed that fitting accuracy of Hii et al. model was better than other models. Practical Applications Sweet potato (Ipomoea batatas L.) is widely grown in many countries. In developing countries, there are many problems related to storage and transport of the raw sweet potatoes. The objective of this study was to investigate the effect of drying temperature and sample thickness conditions on the thin layer drying of sweet potato, and to evaluate a suitable drying model for describing the drying process. In addition, the effective moisture diffusivity and Ea in the drying process of sweet potato slices were calculated.