Multi-Index Analysis and Comprehensive Evaluation of Different Drying Techniques for Citrus Peels Based on Entropy Weight Method

This study examined the effects of hot-air drying (HAD), infrared drying (IRD), and microwave-infrared combined drying (MICD) on the drying characteristics and quality of citrus peels. Increasing temperature and microwave power significantly shortened drying time, with MICD showing the highest efficiency due to its volumetric heating mechanism. MICD also exhibited the highest effective moisture diffusivity and lowest activation energy, indicating enhanced moisture migration, but caused structural collapse and color deterioration. In contrast, HAD and IRD better preserved color and oil gland integrity. Under optimal conditions, MICD and IRD retained higher total phenolic and flavonoid contents, accompanied by superior antioxidant activity. Electronic nose and PCA analyses revealed better volatile flavor retention in HAD and IRD, while microstructural observations showed that IRD produced more uniform and intact tissues. Correlation analysis indicated strong associations among color, flavor retention, and antioxidant activity. The entropy-weight comprehensive evaluation identified IRD at 70 °C as the optimal drying method, balancing efficiency, bioactive compound preservation, and flavor quality. These findings provide practical guidance for selecting energy-efficient drying technologies to enhance the quality of dried citrus peels.