Abstract: Objective: To explore the physicochemical properties of fresh and dried galanga (Alpinia officinarum Hance)
slices, and to further establish a drying method for the maximum retention of bioactives. Methods: The contents of total
phenols and flavonoids in galanga slices were determined by a spectrophotometer, galangin was quantitated by high
performance liquid chromatography, the volatile components were measured by gas chromatography, and the color was
evaluated by a colorimeter. Results: The abilities of different drying methods to retain total phenols, total flavonoids
and galangin were in the decreasing order of freeze drying > vacuum drying > hot air drying > microwave drying > sun
drying > shade drying. The contents of total phenols, total flavonoids and galangin in freeze-dried samples were (20.95 ± 0.13),
(12.19 ± 0.01), and (11.45 ± 0.03) mg/g, respectively. In terms of peak area, volatile components were lower in the
shade-dried and sun-dried samples. On the other hand, the four other drying methods differed little from each other. The
microwave-dried galanga had the deepest color with a* value of 13.92, followed by hot air drying, and the color of freezedried
was the lightest. Conclusion: Freeze drying can be used to produce high-quality products without concern about cost.
Sun drying is available for environmental protection and energy saving. The traditional hot air drying is recommended for
routine industrial production.

Key words: Alpinia officinarum Hance, drying method, total phenols, total flavonoids, galangin, color, volatile components