Drying Kinetics and Thermodynamic Properties of Ultrasound Pretreatment Bitter Melon Dried by Infrared

Abstract

Determination of drying characteristics of ripe and unripe bitter melon in an infrared dryer at 50, 60, and 70°C with airborne ultrasonic pretreatment with a power of 20 kW for 0, 10, and 20 minutes and a frequency of 20 kHz is the purpose of this study. At the end of drying, among the five used models that fit the moisture ratio data, the Midilli and logarithmic models were selected to properly characterize the drying behavior in the infrared dryer with ultrasonic pretreatment of ripe and unripe bitter melon samples. Moisture transfer from bitter melon samples’ ripeness and early maturity was defined using Fick’s diffusion equation. Then, the Arrhenius equation was utilized to determine the effective moisture diffusivity. Also, the activation energy of unripe and ripe bitter melon slices was reduced with the enhancement in the ultrasound pretreatment time. Water activity (aw) amounts of ripe and unripe bitter melon were achieved at various drying temperatures and ultrasound pretreatment. The trends of the experiment indicate a decrease in enthalpy (ΔH) and entropy (ΔS) amounts of bitter melon with enhancing temperature and ultrasonic. The Gibbs free energy (ΔG) increases with enhancing drying temperature and ultrasonic pretreatment. Specific energy consumption decreased with enhancing drying temperature and ultrasound pretreatment duration for both ripe and unripe bitter melon samples.