Drying characteristics of mango slices using the Refractance Window™ technique

Mango slices (1 and 2 mm thickness) were dried by using the Refractance Window (TM) (RW) technique with the water bath temperature set at 92 degrees C. Drying kinetics, water activity, and color change were determined and compared with those obtained by drying the slices in a tray dryer at 62 degrees C and an air velocity of 0.52 m/s. At 1 h, moisture contents of 0.013 (for 1 mm sample) and 0.048 (for 2 mm sample) kg water/kg dry solid for RW, and 0.966 (for 1 mm sample) and 3.614 (for 2 mm sample) kg water/kg dry solid for tray drying were obtained and water activity was less than 0.5 for RW and close to 0.97 for tray drying. The tray dryer took 4 h to reach results similar to those of RW at 1 h. The samples dried by RW exhibited diffusivities of 4.40 x 10(-10) (for 1 mm sample) and 1.56 x 10(-9) (for 2 mm sample) m(2)/s, which are larger than those exhibited by the air-dried samples, 2.08 x 10(-11) (for 1 mm sample) and 6.83 x 10(-10) (for 2 mm sample) m(2)/s. (C) 2011 Elsevier Ltd. All rights reserved.