Abstract
Slices of raw sweet potato were spread on the concrete floor or straw-mat and exposed to the sun before they were dried by fire. In this way it was possible to reduce expenses of electricity or fuel used for drying. Labor cost, however, was high when straw-mats were used. The cost of production of fire-dried sweet potato was 22.5, 23.2, and 26.4 yen per kilogram when the concrete floor, the straw-mat' and no step of sun-drying were employed, respectively before fire-drying.
