Abstract:

The characteristics of infrared radiation drying for papaya at different drying temperatures (60, 70, 80 and 90 ℃)
and powers (675, 1 125, 1 575 and 2 025 W) were discussed in this paper. The results showed that drying temperature had
a significant effect on the drying rate of papaya. The influence of infrared power on the drying rate of papaya was less.
The drying time was reduced with an increase in either drying temperature or infrared power. Infrared drying of papaya
slices mainly occurred in the falling rate drying period. According to the statistical results, the middle- and short-wave
infrared radiation drying behavior of papaya slices were properly described by Henderson and Pabis model among three
mathematical models that were used to fit the experimental data. Better agreement between the predicted and experimental
values was obtained using the selected model. The effective diffusion coefficient increased with increasing air temperature
or infrared power. The effective moisture diffusion coefficient (Deff) ranged from 11.14 × 10-10–29.11 × 10-10 m2/s at different
drying temperatures and from 14.29 × 10-10 -17.22 × 10-10 m2/s at different infrared powers. The calculated activation energy
of middle- and short-wave infrared radiation drying for papaya was 32.13 kJ/mol based on the Arrhenius equation.

Key words: infrared drying, drying characteristics, papaya, effective moisture diffusion coefficient, activation energy