• Drying time;
  • infrared drying;
  • lycopene;
  • rehydration;
  • shrinkage;
  • specific energy consumption;
  • tomato;
  • vitamin C


The effects of air temperature (T) (unheated and 35 °C), infrared radiation intensity (IP) (894, 1004, 1190, 1314 and 1410 Wm−2) and air velocity (Av) (1.0, 1.5 and 2.0 ms−1) on drying characteristics of tomatoes, drying time (DT), specific energy consumption (SEC) and quality parameters were investigated. DT and SEC varied between 114 and 249 min, 10.04 and 18.22 MJ kg−1 water, respectively, and were significantly affected by process variables. Shrinkage ratio (S) and rehydration ratio (Rr) were varied between 0.129 and 0.214, 2.11 and 2.86 for all the drying conditions, respectively. Total colour change (ΔE) varied from 5.30 to 13.19. Vitamin C content decreased, while lycopene content increased with infrared drying. For optimum points, desirability of functions of all targets had satisfactory, very good and excellent desirability values and ranged between 0.54 and 0.99.