Effects of ultrasound-assisted ethanol pretreatment on hot-air drying kinetics and quality of asparagus lettuce

ABSTRACT: This study evaluated the effects of ultrasound (UP), ethanol (EP), and combined ultrasound-ethanol (UEP) pretreatments on the hot-air drying characteristics and quality of asparagus lettuce (AL). UEP exhibited synergism, reducing drying time by 52.21% and energy consumption by 46.88% compared to the control. Microstructural analysis revealed that UEP formed a uniform microchannel network, facilitating moisture migration and accelerating water diffusion. This shortened drying time reduced thermal degradation of bioactive compounds, improving color, vitamin C, chlorophyll, total phenolics, flavonoids, and antioxidant capacity. Correlation analysis confirmed drying time as the central factor linking structural changes to quality outcomes. TOPSIS-EWM identified UEP as the optimal pretreatment. These findings reveal the mechanistic chain from synergistic pretreatment to quality preservation and demonstrate UEP as an effective strategy for enhancing drying efficiency and product quality.