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In situ measurement of white wine absorbance in clear and in coloured bottles using a modified laboratory spectrophotometer

2003; Wiley; Volume: 9; Issue: 2 Linguagem: Inglês

10.1111/j.1755-0238.2003.tb00264.x

1755-0238

George K. Skouroumounis, Mariola Kwiatkowski, Mark A. Sefton, Richard Gawel, Elizabeth J. Waters,

Spectroscopy and Chemometric Analyses

In situ absorbance of visible light by white wine in bottles was determined with a modified spectrophotometer. A linear correlation was obtained between absorbance at 420 nm (A420) measured in a cuvette (10 mm pathlength) and absorbance of that same wine measured in a 750 mL Flint bottle (colourless transparent glass). In addition, 5 types of coloured bottles, Emerald Green, Classic Green, French Green, Georgia Green and Cobalt Blue, also yielded strong correlations. A420 of white wine in bottles of Antique Green or Amber glass could not be measured directly due to a strong absorbance of that wavelength by the glass. However, a strong correlation was established between measurement of A420 (cuvette) and A540 for white wine in Antique Green bottles and between A420 (cuvette) and either A540 or A600 for white wine in Amber bottles. The method employed a standard UV-Visible spectrophotometer with an inexpensive modified sample port, and proved applicable to bottles with diameters ranging from 62 mm (375 mL capacity half bottles) up to 81 mm (750 mL capacity Burgundy bottles). In situ absorbance measurements plus subsequent chemical analysis and sensory assessment of a Chardonnay wine in Antique Green bottles showed that the method provided an estimate of oxidation in this white wine. Wine absorbance spectra over the full visible range were obtained in the Flint bottle. Measurements of the absorbance of visible light by the glass of empty bottles could also be obtained and used as a form of quality control for glass bottle manufacture.