Effects of Drying on Chemical and Physical Characteristics of American Ginseng (Panax quinquefoliusL.)

The influence of air moisture content and temperature of the drying chamber on the color, major carbohydrates, and ginsenosides of Panax quinquefolius L. was investigated in 1994, and 1995. Increasing the rate of air moisture-reduction in the drying chamber (from an initial vapor pressure deficit (VPD) of 1.0 kPa to a final VPD of 4.0 kPa) from 264 h to 48 h had no effect on the chemical characteristics of ginseng and reduced drying time (to 8 percent moisture content) by only 38 h. The most efficient drying occurred with air moisture content reduced to about the 4.0 kPa VPD level in 48 h. Raising the drying temperature from 32° to 44°C reduced tissue drying time to 8 percent moisture content by 91.4 h, darkened root color, reduced concentrations of the malonyl-ginsenosides mRb1, mRb2, mRc, mRd and the neutral ginsenosides Re and Ro, and increased the concentration of gypenoside XVII. Ginsenosides Rb1, Rc, Rd and Rg1 were not affected by drying temperature. Ro and sucrose concentration in tissue increased and starch decreased as drying temperature was reduced from 38° to 32°C. Optimum temperature for drying ginseng was 38°C.