Change of Inorganic Component, Reducing Sugar, Catalpol and Benzo[α]pyrene Contents of Rehmannia glutinosa Libosch. var. purpurea Makino by Drying Methods

This experiment was carried out in order to collect the basic data on the standardization of the manufacturing process of Rehmannia glutinosa Libosch. var. purpurea Makino drying. By the drying methods of R. glutinosa, the content of water, inorganic components, reducing sugar, catalpol and benzo[α]pyrene were investigated. The water content was 15.6~17.2% when R. glutinosa was dried by cold-warm air moisture absorption drying method (CAMAD) at 60℃ during 6 days. Among of the inorganic components of R. glutinosa the K content was the most followed by P, Na, Ca and Mg. The reducing sugar content of R. glutinosa by the hot air drying method (HAD) was much more than that by the CAMAD. The catalpol content of R. glutinosa was not different by the drying temperature when it was dried by the CAMAD. The catalpol content of the large size tuber (about 50.0 g/unit) showed a tendency to increase from 60℃ until 70℃ drying temperature, but that of the small size tuber(about 4.0 g/unit) was decreased as being a trend as the drying temperature high when R. glutinosa was dried by the HAD, But the catalpol content R. glutinosa had a tendency to drop significantly at drying temperature above 80℃. The benzo[α]pyrene content was little detected when R. glutinosa was dried by both the SLD and the CAMAD, and the sampling by the HAD indicated within the scope of 5 ㎍/㎏ which was the scope to regulate by Korean food and drug administration. In conclusion, it seemed that an appropriate drying temperature of R. glutinosa by the CAMAD and the HAD was about 60℃ and about 70℃, respectively, when we consider the catalpol content and benzo[α]pyrene detection in the manufacturing process of drying R. glutinosa.