Application of hot air‐assisted radio frequency as second stage drying method for mango slices
2019
Zhang, Hangjin | Gong, Chuting | Wang, Xiaofan | Liao, Meiji | U̇su̇ru̇nggu̇i, L. | Jiao, Shunshan
This study applied hot air‐assisted RF (HA‐RF) as second stage drying method for mango slices. Hot‐air drying was used as first stage drying to reduce moisture content to about 40% (w.b.), then HA‐RF drying was applied as second stage drying to further reduce moisture content to 18% within 45 min with 4.5 cm sample thickness (hot air temperature: 60 °C, electrode gap: 7.5 cm). The time for the two‐stage drying process was about 5 hr, which was clearly lower than that of hot‐air drying (8 hr) or vacuum drying (7 hr). HA‐RF as second stage drying maintained sample overall quality very well except for minor vitamin C degradation (retention rate: 91%); Overall quality of mango slices after the two‐stage drying was better than that dried by hot‐air drying, and close to that dried by vacuum drying. This study demonstrated HA‐RF could be used as second stage drying method for mango slices. PRACTICAL APPLICATIONS: This study applied HA‐RF heating as second stage drying method for mango slices, and research findings in this study indicated that HA‐RF drying could reduce drying time and improve sample quality. This study proposed a new two‐stage drying method for mango slices, and this technology can be easily scale‐up for commercial application. And the two‐stage drying efficiency and products quality could be further improved by other novel and efficient drying techniques as first stage drying.
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