Study on drying efficiency, uniformity, and physicochemical characteristics of carrot by tunnel microwave drying combined with explosion puffing drying
Yayuan Xu, Xumin Lang, Yadong Xiao, Dajing Li, Chunquan Liu, Jiangfeng Song, Zhongyuan Zhang, Chunju Liu, Ning Jiang, Min Zhang, Cunshan Zhou
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.