Abstract:

Objective: To establish a modified method for the determination of oxygen radical absorbance capacity (ORAC)
in Chinese rice wine by fluorescence spectrophotometry. Methods: Commercial samples of Chinese rice wine were
determined by a fluorescence spectrophotometer for fluorescence half-decay time. As a result, a Trolox calibration curve
was developed and used to calculate ORAC. The analytical method was validated with respect to limit of detection (LOD),
precision for repeated and parallel determinations and spiked recovery. Results: The excitation wavelength was 490 nm,
and emission wavelength was 517 nm. The regression equation between relative fluorescence half-decay time and Trolox
concentration was Y = 7.2357X － 0.8189 with R2 of 0.9948 and detection range of 0.28–8.00 μmol Trolox/L. The precision
for 5 repeated and 5 parallel determinations were 3.02% and 2.69%, respectively. The recovery rates of spiked samples
were in the range of 93.00%–102.00%. The ORAC value of Chinese rice wine was 4.68–5.21 μmol Trolox/mL. Conclusion:
Fluorescence spectrophotometry is a simple, time-saving, accurate, precise and stable method which is useful to determine
ORAC in Chinese rice wines of different ages and from different brands

Key words: Chinese rice wine, fermented alcoholic beverage, oxygen radical absorbance capacity (ORAC), fluorescein(FL), fluorescence spectrophotometry