A promising pulse-spouted microwave freeze drying method used for Chinese yam cubes dehydration: quality, energy consumption, and uniformity

Abstract

Pulse-spouted microwave freeze drying (PSMFD) used for Chinese yam cubes was evaluated at three microwave power levels (400, 600, and 800 W). The drying characteristics, energy consumption, and quality of dried yam cubes were assessed and compared with freeze dried samples. Moreover, the drying uniformity of PSMFD and static microwave freeze drying (MFD) was contrasted. Results showed that drying time decreased and drying rate increased with increasing microwave power levels, furthermore drying rate curves contained three stages. Compared to the freeze drying (FD) process, PSMFD (800 W) could shorten drying time by 55%, and appropriate microwave power (400 and 600 W) contributed to the improvement of crispness. The retention of ascorbic acid and total phenol content of yam cubes dried at 600 W was higher than that of samples dried at 400 and 800 W. In addition, the drying uniformity of PSMFD was improved compared with that of MFD. Considering the high efficiency and comparable quality compared with FD evaluated by principal component analysis (PCA), PSMFD is a promising drying technique.

Keywords:

• Pulse-spouted microwave freeze drying
• yam cubes
• drying characteristics
• different microwave power levels
• drying uniformity

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Linlin Li, PhD candidate in School of Food Science and Technology, Jiangnan University. She is engaged in research of novel drying technology for fresh food, quality evolution mechanism and optimization control.

Min Zhang, Professor and PhD supervisor in School of Food Science and Technology, Jiangnan University. His research areas focus on the Mechanism, Technology and Engineering of Processing and Storage of Fresh Foods.

Weiqin Wang, Director of R&D Center in Haitong Food Group Company.

Additional information

Funding

We acknowledge the financial support from National Key R&D Program of China (Contract No. 2017YFD0400901), Jiangsu Province (China) Agricultural Innovation Project (Contract No. CX(17)2017), National First-class Discipline Program of Food Science and Technology (No. JUFSTR20180205), Jiangsu Province Key Laboratory Project of Advanced Food Manufacturing Equipment and Technology (No. FMZ201803), all of which enabled us to carry out this study.