Investigating the Effects of a Novel Combined Infrared-Vacuum Dryer on the Drying Kinetics and Quality Parameters of Apple Chips

Abstract

In this study, the kinetic and quality parameters of apple chips dried by a novel dryer equipped with two-way infrared heating (180, 275, and 325 W) and vacuum pump systems (100 and 400 mmHg) were investigated. The final drying time of the sample was reduced with the increasing infrared power. However, it significantly decreased with the increasing vacuum pressure at only 180 W. While the rehydration ratio and sugar content decreased at higher infrared power, the degree of browning and 5-hydroxymethylfurfural increased. Apple chips had high HMF contents (205.39-351.30 mg/kg DM). After sensory evaluation, the highest color, crispness, chewiness, taste, and general acceptance values were determined in the apple chips dried at 275 W and 400 mmHg. The results showed that Midilli’s model was the best option to describe the experimental drying data. The effective moisture diffusivity increased with increasing power and ranged from 1.4499 to 2.9362 × 10−8 m2/s. The activation energies of drying kinetics for 100 and 400 mmHg were 40.5507 and 36.5134 kJ/mol, respectively. Results showed that the higher energy efficiency and product quality for apple chips could be obtained with a specially designed infrared vacuum combined dryer (275 W and 400 mmHg). © 2023, Iranian Institute of Research and Development in Chemical Industries. All rights reserved.