Abstract

Tunnel microwave drying (TMD) is commonly applied in industrial production of dried products. In this study, carrot slices were processed by a combined method of explosion puffing drying (EPD) and TMD (TMD-EPD). The drying characteristics and efficiency during TMD pre-drying with different conveyor speeds were studied. Additionally, product quality including color, carotenoids, ascorbic acid, texture, microstructure, rehydration, and shrinkage ratio were evaluated compared to that of hot air drying (HAD) pre-drying and HAD-EPD. The results showed that a lower conveyor speed (0.65 cm/s) could improve the drying uniformity to some extent. A higher conveyor speed (1.30 cm/s) of TMD-EPD led to better texture attributes, higher rehydration capacity and less shrinkage in diameter compared to HAD-EPD. The microstructure of TMD-EPD samples was more expanded and porous than that of HAD-EPD. Furthermore, TMD could reduce the time of pre-drying process and subsequent EPD process in comparison with HAD-EPD.

摘要

隧道微波干燥 (TMD) 常用于干燥产品的工业生产。在本研究中，胡萝卜切片采用爆炸膨化干燥 (EPD) 和 TMD (TMD-EPD) 的组合方法进行加工。研究了不同输送速度下TMD预干燥过程中的干燥特性和效率。此外，与热风干燥 (HAD) 预干燥和 HAD-EPD 相比，还评估了产品质量，包括颜色、类胡萝卜素、抗坏血酸、质地、微观结构、再水化和收缩率。结果表明，较低的传送带速度（0.65 cm/s）可以在一定程度上提高干燥均匀性。与 HAD-EPD 相比，更高的 TMD-EPD 传送带速度 (1.30 cm/s) 导致更好的质地属性、更高的再水化能力和更少的直径收缩。TMD-EPD 样品的微观结构比 HAD-EPD 更膨胀和多孔。此外，与 HAD-EPD 相比，TMD 可以减少预干燥过程和后续 EPD 过程的时间。