Abstract: Western Hunan natural savory vinegar was analyzed by UV, infrared and fluorescence spectroscopy for variations in spectroscopic characteristics during ageing. The vinegar was found to have characteristic absorption mainly in the near UV region of 200–400 nm. The UV absorption intensity increased, but irregular variations in the symmetric stretching vibration of hydroxyl groups and significant variations at 2351 cm-1 were found in the infrared spectrum with increasing aging time. The fluorescence spectrum of the vinegar presented considerable variations with increasing ageing time, and the fluorescence intensity displayed a general declining trend and dramatically declined when the ageing time exceeded 3 years; meanwhile, the number of emission peaks deceased from 3 to 2. During ageing, physicochemical variations of the vinegar are associated with variations in its spectroscopic characteristics. Hence, spectroscopy can provide an approach for identifying the ageing time of Western Hunan natural savory vinegar.

Key words: Western Hunan natural savory vinegar, ageing year, UV spectroscopy, FT-IR spectroscopy, fluorescence spectroscopy