Research on variable-temperature drying process of Zhaotong Gastrodia elata Bl. f. glauca S. Chow / 中草药

ABSTRACT

Objective: To put an end to events of sulfur content over-standard in Zhaotong Gastrodia elata Bl. f. glauca S. Chow (ZGE) and to improve the drying efficiency. Methods: Effects of steaming time and drying parameters on phenomenal and quality characteristics of ZGE were investigated. Drying process of ZGE adapt to modern process equipment was explored. Results: Optimal steaming time for second grade fresh ZGE was 4 min under 95℃. Suitable drying process parameters were as follows ZGE was natural cooling at room temperature for 12 h after steamed. ZGE was drying at 30℃ for 1 d, and then the temperature was raised with the speed of 2℃/12 h to 40℃. Then with the speed of 5℃/12 h until to 60℃, all the work can be stopped until the ZGE was dried completely. It totally took about 6 d. ZGE appeared light brown and less deformation, and the fold was shallow, without hollow. The content of gastrodin was 0.93%, soluble extract content was 20.1%, and the content of total ash was 2.65%. All quality indexes were corresponded to the standard of Chinese Pharmacopoeia 2010. Conclusion: Drying process of ZGE was applied to modern processing equipment. It can not only guarantee the phenomenal but also the quality of ZGE. Meanwhile, it can improve the production efficiency and was suited to demonstrate and extend in Zhaotong region.