Effect of Microwave Vacuum Drying on Quality Characteristics of <i>Dendrobium officinale</i>
Welcome to Chinese Journal of Tropical Crops,

Chinese Journal of Tropical Crops ›› 2020, Vol. 41 ›› Issue (7): 1459-1468.DOI: 10.3969/j.issn.1000-2561.2020.07.024

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Effect of Microwave Vacuum Drying on Quality Characteristics of Dendrobium officinale

LIN Hong,WANG Weiwei,ZHENG Baodong,GUO Zebin()   

  1. College of Food Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
  • Received:2019-09-20 Revised:2019-10-29 Online:2020-07-25 Published:2020-08-24
  • Contact: GUO Zebin


The microwave vacuum drying method was used to dry Dendrobium officinale. The effects of microwave vacuum drying on the quality characteristics of D. officinale were studied by measuring the content of polysaccharides, color, polyphenol oxidase (PPO), water distribution, Composition of amino acids and DPPH? and ?OH scavenging rates of polyphenols. When the microwave intensity was 9 W/g compared with the fresh sample, the dried sample had the highest polysaccharide content of 52.21%. The content of total free amino acids and flavor amino acids of D. officinale was significantly increased after microwave vacuum drying. PPO activity of D. officinale after microwave vacuum drying at microwave intensity of 9 W/g, 12 W/g and 15 W/g was no longer present at the 16th, 12th and 6th minutes respectively, indicating that microwave vacuum drying could inactivate PPO activity of D. officinale in a relatively short time, and higher microwave intensity would lead to shorter time. Non-enzymatic browning in drying process was caused by Maillard reaction. The free water relaxation time T23 and A23 decreased significantly. The free radical scavenging ability of D. officinale showed that the hydroxyl radical scavenging ability was still strong. By observing the microstructure of the sample after drying, the pore structure of the sample was seriously damaged with the increase of microwave power density. The rehydration characteristics of D. officinalis showed that higher microwave intensity resulted in better rehydration characteristics.

Key words: Dendrobium officinale, microwave vacuum drying, amino acid, polysaccharide, quality characteristic

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