Alternative processing technology for the preparation of carbonized Zingiberis Rhizoma by stir-frying with sand

CONTEXT: Carbonized ginger, a type of charry herb, has been used as a hemostatic medicine since ancient times. However, there are some serious problems such as inhomogeneous heating and emitting smoke during processing with traditional stir-frying method. OBJECTIVE: To investigate the feasibility to obtain carbonized ginger by stir-frying with sand instead of stir-frying method. MATERIALS AND METHODS: Dried-ginger (100 g) was processed by stir-frying for 30 min at 270 ± 10 °C, or by stir-frying with sand (1:10, w/w) for 8 min at 240 ± 5 °C. The HPLC fingerprint was established for two samples. The adsorption capacity and major components including tannins, gingerols, shogaols and gingerone were quantitated by UV and HPLC, respectively. The hemostatic effect by prothrombin time (PT) and activated partial thromboplastin time (APTT) was evaluated in vitro. RESULTS: The similarity of the two samples for HPLC fingerprints was >0.93. The sand-fried samples showed significantly higher adsorption capacity compared with the stir-fried samples (4.915 vs. 4.593 mg/g; p < 0.05) and higher contents of major components (4.698 vs. 3.930 mg/g, 1.352 vs. 1.144 mg/g, 2.419 vs. 2.095 mg/g, 0.666 vs. 0.568 mg/g and 1.083 vs. 0.911 mg/g for tannins, gingerone, 6-shogaol, 8-shogaol and 10-shogaol, respectively; p < 0.05); while no significant differences were seen for 6-gingerol, 8-gingerol and 10-gingerol (p > 0.05). The PT and APTT values were similar between the stir-fried and sand-fried test groups and significantly lower compared to controls (p < 0.05). CONCLUSIONS: The carbonizing process by stir-frying with sand is superior to the stir-frying method for carbonized ginger.