Optimization of Spray Drying Without Drying Carriers from Rehmannia glutinosa L. Root and Coix lachryma- jobi L. Trunk

Abstract

Spray drying is a well-known method for preparing dried extracts from herbs. Rehmannia glutinosa root and Coix lachryma-jobi trunk are widely researched especially for diabetes treatment. The optimization of extraction conditions, namely the alcohol concentration, treated herbs and solvent ratio, extraction temperature, and time. The extracts are dried by Labplant machine with two specifications (drying inlet air temperature and flow- rate). Rehmannia glutinosa root is extracted by refluxing method for 60 minutes with 40% alcohol, the ratio of treated herbs and solvent was 1:3, at 800C by three times extract and its dried extract is prepared at a drying inlet air temperature of 90oC, 8 cycles per minute. Coix lachryma-jobi trunk is also extracted by the same method for 60 minutes with 80% alcohol, the ratio of treated herbs and solvent was 1:6, extraction temperature and time are respective 80oC and two times, spray drying conditions were 80oC (drying inlet air temperature) and 4 cycles per minute (flow- rate). The obtained dried extracts of Rehmannia glutinosa root and Coix lachryma-jobi trunk have average moisture contents of 4.52% and 3.84%, respectively. Therefore, this study is a novel approach to significantly decreasing the amount of carriers to reduce research's funds and saving dried extracts' price.