Optimization of Tomato Slices Drying in a Continuous Infrared-Assisted Refractance WindowTM Dryer Using Response Surface Methodology

The present work aimed to investigate the energy consumption and quality of tomato slices dried in an InfraRed-Assisted Reflectance Windowtm (IRARW) dryer. The response surface methodology was used to optimize the experimental factors, including water temperature, infrared (IR) power, and belt speed based on specific energy consumption, IR fraction, contents of ascorbic acid, total phenolic, and total lycopene and color indices (L*, a*, b*, and H°). All factors, except the belt speed in the range of 0.278 - 0.37 mm/s, had significant effects on the performance parameters. The maximum measured value of specific energy consumption, IR fraction, contents of ascorbic acid, total phenolic, and total lycopene were 1.76 kWh/kg, 60.4%, 302.2 mg/100g, 708.07 mg GAE/100g, and 38.61 mg/100g, respectively. Rising the IR power led to an increase in a* and a decrease in L* values of the color indices. The optimum drying condition was determined to be at the temperature of 70 °C and the IR power of 500 W.