Method for preparing dendrobium nobile freeze-dried powder by combining microwave with variable-temperature freezing

The invention provides a method for preparing dendrobium nobile freeze-dried powder by combining microwaves with variable-temperature freezing, and relates to the technical field of dendrobium nobile processing. The preparation method of the dendrobium nobile freeze-dried powder mainly comprises the following steps: freezing fresh dendrobium nobile in stages, pre-unfreezing by microwaves, carrying out variable-temperature ultrasonic extraction, concentrating, evaporating and freeze-drying to obtain the dendrobium nobile freeze-dried powder. According to the method, the defects in the prior art are overcome, the extraction rate and extraction efficiency of effective substances in dendrobe are improved, meanwhile, the antioxidant activity of polysaccharide in the dendrobe freeze-dried powder is improved, and the health-care property of the prepared freeze-dried powder is improved. 本发明提供一种微波联合变温冷冻制得石斛冻干粉的方法，涉及石斛加工技术领域。所述石斛冻干粉的制备方法主要为将鲜石斛进行分级冷冻后微波预解冻，再变温超声提取后浓缩蒸发冻干制得。本发明克服了现有技术的不足，提高了石斛中有效物质的提取率和提取效率，同时提升石斛冻干粉中多糖