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CIELab as a reference method for the analysis of wine color

Technology now makes it possible also in a small cellar

CIELab as a reference method for the analysis of wine color

The first characteristic that a wine consumer has the opportunity to evaluate, right from the bottle if the color of the glass allows it or in the glass when pouring the wine, is the color.

Although probably the majority of consumers do not use objective evaluations and do not have the bases to use the color of what they are going to drink as a qualitative parameter, they still associate the color of the wine with its quality and, consequently, are influenced by the color in purchasing decisions. Whether it is right or not, they are the ones who buy and the color impacts their decision!

There is a scientific explanation for this. In fact, it has been shown that the color of wine also impacts and changes the olfactory perceptions... yes, you got it right... the color changes the olfactory perceptions! An experiment conducted by researchers from the University of Bordeaux in collaboration with the IRNA research center and published in the scientific journal Brain and Language, has shown that the color of wine is really capable of changing the olfactory perception of that wine due to a perceptual illusion. Read the article here.

In the experiment, a white wine artificially colored red with an odorless dye was described from the olfactory point of view as a red wine by a panel of 54 tasters.

In particular, color is a very important parameter for white and rosé wines. The market for these wines has been growing steadily for over 20 years and their consumption is no longer concentrated only in summer and/or for special and limited occasions (such as aperitifs), but the demand is always higher and more constant during all the year. In addition to influencing the customer's choice (a phenomenon now demonstrated by various sector studies), for these wines the color represents an important parameter of quality control of the wine because it changes with aging due to oxidation, that means also a change in the organoleptic properties of the wine.

Color is therefore a very important qualitative parameter of wine that deserves the same dignity and attention in the control of all the other parameters (sugars, malic, total acidity, pH, etc ...). On the other hand, it is the first parameter that is evaluated in the tasting phase in competitions [disciplinary research where color is regulated].

So why don't you analyze it? Or if so, why do you do it with obsolete methods?

As for all other wine quality control analysis parameters, the OIV (International Organization of Vine and Wine) has defined the standards for measuring and evaluating the color of wine in an objective way. The recognized standards are two:

The type I methods of the OIV are the methods considered unique and best, as there are no other methods to obtain that type of value for the parameter in question. In other words, there are no other systems other than that based on the CIE standard for determining the color of wine according to the CIELab method. Type IV methods, on the other hand, are defined as "auxiliary" methods, that is, they are conventionally used when "higher" grade methods, such as type I, cannot be used.

The method of evaluating the color according to the "Chromatic Characteristics" standard is known to all and certainly the most used still today. It is based on the spectrophotometric reading of Absorbance (or optical density D.O.) at the three wavelengths 420 nm, 520 nm, 620 nm, from which the Intensity is then calculated, adding the D.O. of the 3 wavelengths, and the Tone, making the relationship between the D.O. measured at 420 nm and 520 nm. Historically, it was born and is still used today because the analysis can also be performed with poorly performing instruments, such as old spectrophotometers or simple photometers. In addition, they do not require special software because the calculations to be made are simple (a sum and a ratio).

Until recently, there were no systems that allowed CIELab analysis to be carried out easily, directly in the cellar. But now, thanks to technology, it is possible to have CIELab color analysis available for anyone.

Keep reading

Published on 09/21/2020
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