Purple-Fleshed Sweet Potato Cubes Drying in a Microwave-Assisted Spouted Bed Dryer |
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| Authors: | Peng Liu Arun S. Mujumdar |
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| Affiliation: | 1. State Key Laboratory of Food Science and Technology , Jiangnan University , Wuxi , Jiangsu , China;2. State Key Laboratory of Food Science and Technology , Jiangnan University , Wuxi , Jiangsu , China;3. Department of Food Engineering, Faculty of Engineering , King Mongkut's University of Technology Thonburi , Bangkok , Thailand |
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| Abstract: | Purple-fleshed sweet potatos (PFSP) were loaded into a laboratory-scale, microwave-assisted spouted bed with a coating of sodium alginate (SA) of 0, 0.2%, 0.4%, 0.8% (w/w) for both steam-blanching pretreated and fresh-cut raw samples. The drying curves, rehydration ratio, and maximum penetrating forces were studied for final products; color changes and anthocyanin level were also taken into consideration. It was concluded that coating processing forms barriers to moisture content, which changes the dielectric properties of PFSP cubes and shortens the drying time; however, coating PFSP cubes with SA did not lead to a porous microstructure in the final products. The final hardness was high and rehydration ratio was low. Steam-blanching was helpful for color and anthocyanin-level retention compared with raw samples. In sum, microwave-assisted spouted bed (MWSB) drying of PFSP cubes is not an ideal processing method, even with coating treatment, but blanching is an approach to obtain products with high anthocyanin level and fine purple color. |
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| Keywords: | Anthocyanin Color Microwave-assisted spouted drying Purple-fleshed sweet potato Rehydration ratio |
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