Drying of steamed Asian ginseng (Panax ginseng) roots by microwave-hot aircombination

Steamed Asian ginseng (Panax ginseng) roots were dried by a combined microw ave-hot air method in a modified experimental microwave oven. Hot air dryin g was used as a reference method. The drying time to achieve the desired mo isture level (10%) as well as the ginsenoside contents and the color of the final product were determined. The ginsenosides Rbl, Rb-2, Re, Rd, Re, Rf, Rg(1) and Ro were analyzed by HPLC. Compared with hot air drying, the comb ined microwave-hot air drying method resulted in a substantial decrease (ap proximately 30-40%) in drying time and had little influence on the ginsenos ide contents and the color of the final product.