Effect of ultrasound pretreatment on the drying characteristics and quality of Tremella fuciformis under heat pump drying.

From the paper

Abstract

To enhance the heat pump drying (HPD) efficiency and quality of Tremella fuciformis (T. fuciformis), this study employed ultrasound pretreatment and evaluated its effects on drying behavior and product attributes at various ultrasound intensities [0.00 (the control group, CK), 0.20, 0.34, 0.54, and 0.74 W/g]. The results showed that ultrasound pretreatment significantly accelerated the drying process. The 0.34 W/g pretreatment group achieved the shortest drying time (855 min), which was 9.52% shorter than the CK group (945 min) (p <0.05), and improved the rehydration rate by 7.25% (1220.50 ± 24.75%) compared to the CK group (1138.00 ± 1.41%) (p <0.05). The polysaccharide content reached a maximum value of 24.80 ± 0.25 % at 0.54 W/g, which was 14.44% higher than that of the CK group (21.67 ± 0.26%) (p <0.05). The chromatism remained stable. The microstructure and moisture migration analysis showed that ultrasound pretreatment promotes the formation of porous and loose microstructures in T. fuciformis, which homogenizes the spatial distribution of moisture inside the tissue and enhances moisture diffusion during the HPD process. However, the soluble protein content showed a reduction. Based on a comprehensive evaluation, ultrasound intensities of 0.34 ∼ 0.54 W/g are recommended as the optimal pretreatment range. This study provides theoretical guidance and practical data support for optimizing the drying process and promoting industrial application of T. fuciformis.