Effects of Drying Conditions on Dehydration Characteristics and Quality Attributes of Crab Apple Slices Under Continuous Microwave Drying

Abstract

The use of continuous microwave drying has been proven to be an effective alternative technique to traditional drying, thus gaining advantages in the product quality and processing efficiency. The aim of this study was to investigate the effect of important operating parameters on the dehydration behaviour and quality characteristics of crab apple slices (CAS) by using continuous microwave drying. Slice less thickness, microwave power, air velocity and drying time were systematically investigated for the changes in temperature, moisture reduction, color, texture, total phenolic content and microstructural changes. The initial sample mass of each batch of 16 slices was 22 ± 2 g (1 mm), 33 ± 2 g (1.5 mm) and 44 ± 2 g (2 mm), respectively. The treatments were replicated three times, making a total of 80 experimental units. An R package was used to analyze data using ANOVA with Fisher's LSD test. The results revealed that microwave power, slice thickness, air velocity and drying time were significantly effective in increasing the rate of moisture removal. The microstructural changes due to different temperature profiles during drying had strong influences on quality attributes such as color retention, texture and total phenolic content. The suitable drying conditions were determined as a slice thickness of 1.5 mm, the microwave power as 15200 W, the air velocity as 0.5 m/s and drying time as 13 min. The results provide useful application recommendations in optimizing continuous microwave drying process for improving efficiency and product quality of crab apples and other fruit products. Keywords: Crab apple slices, continuous microwave drying, dehydration, quality attributes, microstructure.