Drying characteristics and quality of Chinese yam by multiphase microwave drying based on fractal theory

Abstract

A multiphase microwave drying (MMD) was proposed to produce dried Chinese yam cubes with good quality comparable to freeze-dried products. The effects of different microwave power loading schemes on the conversion point (water phase in samples changes from solid-to-gas to liquid-to-gas) of MMD were assessed, and the macroscopic physical properties and microstructure characteristics of dried yams were investigated. Results showed that with an increase of microwave power, the time required to reach the conversion point was reduced. And the moisture content at the conversion point as affected by microwave power loading schemes had vital influence on sample quality. When it was 0.378 g·g⁻¹, the properties of the yam cubes resembled those of freeze-dried samples in terms of rehydration, texture, and microstructure. Furthermore, a fractal theory-based microstructure characterization can accurately reflect texture characteristics. MMD has the potential to produce high quality products that matched to freeze-dried ones.

Keywords:

• Multiphase microwave drying
• Chinese yam
• Porosity
• Fractal theory

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

We acknowledge the financial support from National Natural Science Foundation of China (Contract No. 32172352 and No. 31972207), Guangxi Natural Science Foundation of China, (Contract No. 2020GXNSFAA259093), Key Science and Technology Program of Henan Province (Contract No.212102110077), Young Teacher Funding Program of the Henan Higher School (Contract No. 2020GGJS072), Key Scientific Research Projects of Institutions of Higher Learning of Henan (Contract No. 22A550005) and the introduction of foreign intellectual special of Henan Province (Contract No HNGD2021040) all of which enabled us to carry out this study.