New Insights into Wine Color Analysis: A Comparison of Analytical Methods and their Correlation with Sensory Perception

Abstract

Two spectrophotometric methods are recommended by the Organisation Internationale de la vigne et du vin (OIV). The first is the method after Glories, were the absorbances at 420 nm, 520 nm and 620 nm are measured (OIV 2006a). The second method, from the Commission Internationale de L’Eclairage (CIE), uses the entire spectrum from 300 nm to 800 nm to calculate the CIE Parameters L*, a*, and b*. While the OIV recommends a data interval of 5 nm for the CIE method, no such recommendations are given for other parameters such as the scan speed (OIV 2006b). To investigate the parameter settings wines from a dark red grape variety (Merlot), a light red grape variety (Vernatsch) and a white grape variety (Chardonnay) were measured with different data intervals and scan speeds.
Results indicate that the scan speed and data interval have significant impact on the color measurement and the accuracy is dependent from the lightness of a wine. Since both, the Glories system and the CIE L*a*b* system, are widely used in wine analysis it is important to know if those systems are comparable. With the analytical results in mind the correlation has to be conducted for dark red wines, light red wines and white wines. The analysis of 112 wines (56 red wines and 56 white wines) from different grape varieties, origins, and vintages, using both the Glories and CIE methods revealed that the correlation between
the two methods is only possible for dark red wines. Furthermore it is unclear which of the methods are more consonant with the sensory perception. Due to the lack of standardisation a new method of color evaluation was developed. The CIE L*a*b* system better reflects sensory perception than the Glories system, but both systems cannot describe every facet of wine color

References

OIV (2006)a. Determination of chromatic characteristics according to CIELab, Method OIV-MA-AS2-07B. COMPENDIUM OF INTERNATIONAL ANALYSIS OF METHODS, OIV.
OIV (2006)b. Determination of chromatic characteristics according to CIELab, Method OIV-MA-AS2-11. COMPENDIUM OF INTERNATIONAL ANALYSIS OF METHODS, OIV.