Multi-objective optimization of savory leaves drying in continuous infrared-hot air dryer by response surface methodology and desirability function

• Published in: Computers and electronics in agriculture 2020-01, Vol.168, p.105112, Article 105112
• Main Authors: Darvishi, Hosain, Farhudi, Zanyar, Behroozi-Khazaei, Nasser
• Format: Article
• Language: English
• Subjects: Air temperature; Continuous dryer; Desirability function; Drying; Energy consumption; Moisture removal; Multiple objective analysis; Optimization; Optimization, color; Parameters; Response surface methodology; Savory leaves; Velocity
• ISSN: 0168-1699; 1872-7107
• DOI: 10.1016/j.compag.2019.105112

•Effects of drying variables was optimized on continues infrared-hot air drying of savory leaves.•The optimal conditions are designated by maximum desirability function (D = 0810).•Energy consumption increased with increasing temperature and air velocity and decreasing of infrared power.•Effects of air velocity and drying air temperature on color change depended on infrared power density.•Increasing moisture removal rate reduced the rehydration ratio. Drying process of savory leaves was optimized in conveyer-belt infrared-hot air dryer using response surface methodology and desirability function. Effect of air temperature (40–60 °C), air velocity (0.5–1.5 m/s) and infrared power density (0.181–0.253 W/cm2) investigated on drying time, moisture removal rate (MRR), specific energy consumption (Esc) and quality parameters. Drying time varied between 26.0 and 53.9 min. Specific energy consumption increased with increasing temperature and air velocity and decreasing of infrared power. The MRR varied between 0.193 and 0.398 kg water/h. Color change (ΔE) increased with increasing drying temperature and air velocity at high levels of infrared power density (0.253 W/cm2) and decreased at low infrared power density (0.181 W/cm2). The air velocity had no significant effect on the rehydration ratio (RR) of dried samples. Optimization of the drying parameters for the given constraints resulted in 40 °C, 0.53 m/s and 0.250 W/cm2. At this optimum condition, the values of experimental test were found to be 14.05 (ΔE), 2.94 (RR), 10.50 MJ/kg water (Esc), 29.83 min (drying time) and 0.350 kg water/h (MRR), respectively, with desirability factor of 0.810.