Abstract: After 10 h of infusion in different concentration of sugar solution (10%, 15%, 20%, 30%, 40%, 50% or 70%), sweet potato slices were subjected to hot air drying and then examined for hot air drying characteristics and effective moisture diffusivity. The drying data were fitted to Newton, Page, and Henderson and Pabisnine models. The results showed that Page model fitted best with R2 value of 0.982. The sugar content c had a linear relationship with the parameter k, but no relationship with the parameter n. The effective moisture diffusivity Deff under various levels of c were calculated and compared. It was found that Deff had a significant cubic relationship with the initial sugar content value c, with R2 value of 0.984. The pre-exponential factor D0 and activation energy Ea were calculated based on the Arrhenius relationship. Both D0 and Ea value of sugar infused sweet potato slices were larger than those of slices without sugar infusion treatment.

Key words: sugar infusion, sweet potato, hot-air drying, mathematical model