The aim of this study was to prepare instant green tea powder by microwave vacuum drying from green tea concentrate separated by membrane. The response surface methodology (RSM) was used to optimize the process based on a single factor, used the sensory evaluation of green tea powder. The differences of green tea powder prepared by microwave vacuum drying (MVD) and spray drying (SD) were compared in microstructure , contents of tea polyphenols, caffeine and catechins. The characteristics of porous block of the green tea powder prepared by MVD were detected by electron microscope. Compared with particles and powdery characteristics of the powder produced by SD , the loss of industrial production could be effectively reduced by the MVD method. The contents of tea polyphenols, caffeine and catechins in the bottom layer were higher than those in the top layer, and that of the tea powder prepared by SD method was between them. The optimized conditions were: The microwave power 0.81 W/g, the rotary speed 4.09 r/min and the thickness of the concentrated liquid 6 mm. The results of this study can be used as a reference in the industry to produce instant tea by MVD.
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