[Optimization of Suitable Drying Processing Methods of Angelica dahurica].

Objective: To optimize the suitable drying processing methods of the root of Angelica dahurica by the appearance and the content of active compounds.

Methods: 19 methods including natural drying in the shade, natural drying in the sun, hot air drying, shortwave infrared radiation drying were studied. HPLC-PDA method was adopted to determine the contents of coumarin compounds. GC-MS with internal standard method was used to determine the content of volatile oil. The appearance of samples was evaluated by the method of composite scores.

Results: The results of coumarins contents showed that the natural drying in the sun was higher than natural drying in the shade, variable-temperature drying was the best, and the temperature of constant temperature drying was inversely proportional to the contents of coumarins. The results of volatile oils contents showed that variable-temperature drying was the best, and the temperature of constant temperature drying was inversely proportional to the contents of volatile oils. The results of composite scores showed that hot air drying in 50 ℃ was the best, followed by natural drying in the sun, natural drying in the shade and shortwave infrared radiation drying in 50 ℃.

Conclusion: Therefore,considering the drying time,the appearance,and the content of active compounds,the hot air drying method and hot air machine with temperature and humidity controlled was recommend. The suitable parameters for the machine were that the drying temperature was 50 ℃,and the humidity was 35%. The method could provide the reference for the drying technology standard of roots such as Angelica dahurica.