Effect of ultrasound-assisted osmotic dehydration pretreatment on the infrared drying of Pakchoi Stems

Abstract

The effect of ultrasound-assisted osmotic dehydration (UOD) prior to infrared drying (IR) on the drying time and quality properties of dried Pakchoi stems was studied. Results suggested that the ultrasound application could significantly increase the mass transfer during the osmotic process. The UOD pretreated samples showed higher relaxation times of T₂₃ and lower relative signal intensities of A₂₃ using low-field nuclear magnetic resonance (LF-NMR) analysis. Moreover, the cell structural damage and mircrochannel formation caused by the UOD pretreatment resulted in a 25 ∼ 42% reduction in drying time. Although, the chlorophyl and ascorbic acid contents of IR dried Pakchoi stems with UOD pretreatment were relatively lower in comparison with those of untreated samples, the color was better retained and the rehydration ratio was significantly improved by UOD pretreatments.

Key Words:

• Pakchoi stems
• ultrasound assisted osmotic dehydration
• LF-NMR
• infrared drying

Disclosure statement

All of coauthors (Xiao-fei Wu, Min Zhang, Arun S. Mujumdar and Chao-hui Yang) declare that they have no conflict of interest.

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), Jiangsu Province Key Laboratory Project of Advanced Food Manufacturing Equipment and Technology (No. FMZ201803) , Jiangsu Province(China) “Collaborative Innovation Center for Food Safety and Quality Control”Industry Development Program, National First-class Discipline Program of Food Science and Technology (No. JUFSTR20180205), all of which enabled us to carry out this study.