Sour lemon drying by hot air drying under ultrasonic pre-treatment

Document Type : Research Article


1 PhD student, Department of Biosystems Engineering, University of Mohaghegh Ardabili, Ardabil, Iran.

2 Associate Professor, Department of Biosystems Engineering, University of Mohaghegh Ardabili, Ardabil, Iran.


The purpose of this research is to obtain the thermodynamic properties of lemon drying under the influence of ultrasonic pre-treatment in a hot air dryer. Experiments were performed using a convection dryer with ultrasound pretreatment in 40, 55 and 70 °C air temperature, 1 m/s air velocity and duration of ultrasonic pre-treatment of 0 min (for control sample), 10, 20 and 40 min. The drying kinetic of the lemon was estimated by 14 mathematical models. The results showed that the drying time decreased with increasing the air temperature and the time of applying ultrasound. The best model to predict the drying of lemons was selected by Midilli et al. The use of ultrasonic pre-treatment at different temperatures resulted in a significant increase in the effective moisture diffusivity ( ) from 5.04×10-11 to 2.00×10-10 m2/s. Activation energy ( ) of the lemon was obtained between 34.93 and 42.97 kJ/mol. The values of specific energy consumption ( ) were 47.39 to 240.46 kWh/kg.

Graphical Abstract

Sour lemon drying by hot air drying under ultrasonic pre-treatment


  • The engineering properties of sour lemon at the drying process in hot-air dryer were investigated by ultrasound pre-treatment.
  • The effect of air temperature and ultrasound pre-treatment on specific energy consumption, activation energy and effective moisture diffusion were investigated.
  • Increasing the application time of ultrasound pre-treatment and air temperature increased the effective moisture diffusivity.
  • The lowest specific energy consumption occurred at the highest air temperature and time of ultrasound pre-treatment.


Main Subjects

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