Effects of Steaming and Drying on Sugar Content in Ginger
Yuto Nishidono, Ken Tanaka, Toshio MorikawaABSTRACT
Aim
In Japan, Ginger and Processed Ginger are used as crude drugs prepared from ginger rhizomes and are prescribed for distinct clinical purposes. To better understand the chemical basis underlying these differences in clinical use, this study systematically investigated the effects of individual preparation steps on the sugar composition of ginger.
Methods
Fresh ginger rhizomes were either steamed or left untreated and subsequently dried by freeze‐drying or oven drying. The effects of steaming, drying method, oven drying time, and oven drying temperature on sugar composition were examined. Fructose, glucose, and sucrose levels were analyzed by LC/MS. Additionally, we examined commercially available Ginger and Processed Ginger samples from seven manufacturers.
Results
Steaming alone resulted in only a modest decrease in sucrose content, whereas oven drying markedly reduced sucrose levels in non‐steamed samples. Prior steaming significantly suppressed sucrose loss during subsequent oven drying. In non‐steamed samples, sucrose degradation exhibited clear temperature dependence and occurred predominantly at higher drying temperatures (50°C–60°C). TLC analysis of commercial products revealed sucrose in all Processed Ginger samples as well as in several Ginger samples.
Conclusion
These results demonstrate that sucrose retention in Processed Ginger results from the suppressive effect of steaming on sucrose degradation during subsequent oven drying, rather than from steaming alone. These findings emphasize the significance of considering how the effects of individual processing treatments are influenced by subsequent processing steps, including drying, when evaluating changes in the chemical composition of crude drugs.