CHANGES IN CIELAB CHROMATIC PROPERTIES OF WHITE WINES WITH MODELED HIGH CONTENTS OF SULFUR DIOXIDE

Abstract

Using the CIELAB method, the influence of extremely high doses of sulfur dioxide (from about 300 to about 1200 mg/L) in experimental-model white wines prepared from 31 samples of white wines from the Western Balkan region on changes in the chromatic properties of the wine was investigated. By spectrophotometric measurements and calculations, the values of the CIELAB indicators L* (clarity), a* (color along the red-green axis), b* (color along the yellow-blue axis) and ΔE* (overall colorimetric difference between the two wines) were determined. In the analyzed basic wines, the contents of free and total sulfur dioxide were found to be below the legally prescribed maximum concentrations in wines that are on the market. Changes in the values of indicators L*, a* and b* did not follow linear increases in sulfur dioxide content in experimental-model wines. However, on average for all wines, with increases in the content of sulfur dioxide in the specified range, there was an increase in the value of L* by about 1.6 units, a shift in the value of a* by about 1.5 units in a greener direction, and a shift in the value of b* in the direction of less yellow by about 2.3. Setting the value ΔE ≥ 2 as a difference in the color of the wine that could be determined visually, it was found that the modeled strong increase in the content of sulfur dioxide in the wines led to a significant change in color in about 65% of the analyzed wines. The predominant contribution to presumably visible changes in colors of the modeled wine came from changes in the value of the parameter b*. Bearing in mind the significant changes in the color of white wines noted in this research at the first model increase in sulfur dioxide content (by 200 mg/L), it would be useful to investigate changes in the color of white wines at different thresholds of increasing sulfur dioxide content up to this level.