The effect of ultrasonic pretreatment on the drying kinetics of orange peels under different drying methods
Yuhong Lin, Jiantao Yu, Dan Huang, Yuan Chen, Yangyang Fu, Liqiang Zhang, Guohai Jia
Abstract
Citrus peel is rich in various beneficial nutrients, but due to its high moisture content, it is susceptible to bacterial and microbial invasion, thus requiring effective drying methods to extend its shelf life. This article explores the effects of hot air drying (HAD), infrared drying (ID), and infrared convection drying (ICD) methods assisted by ultrasonic pretreatment on the drying characteristics of orange peels, with a focus on the moisture content, color change, rehydration rate, total phenols, total flavonoids, and microstructure of orange peels. The experimental results showed that ultrasonic pretreatment could significantly damage the surface structure of orange peel, accelerate the drying process, and achieve the best drying effect under appropriate ultrasonic time and power. After ultrasonic pretreatment, the drying time was shortened by 42.85 % compared to the control group, and the rehydration rate, total phenolic content, and total flavonoid content were increased by 14.89 %, 13.04 %, and 16.13 %, respectively. The optimal drying method for orange peel was ultrasonic pretreatment (300 W, 15 min) followed by infrared drying. A genetic algorithm optimized long short-term memory model (GA-LSTM) was established to predict the changes in orange peel moisture ratio under complex drying conditions. The findings in this study are expected to provide an efficient and quality-preserving drying strategy for citrus processing byproducts, contributing to sustainable resource utilization and circular economy in the fruit processing industry.