Wine color with the cielab method in winemaking process
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In thE article, prof. Valentina Canuti FROM THE UNIVERTISY OF FLORENCE describes how to quickly approach in the cellar the measurement of wines with the cielab coordinates method in the different stages of winemaking, to evaluate their stability and evolution
THE CIELAB METHOD CAN PROVIDE FUNDAMENTAL INFORMATION IN DIFFERENT OENOLOGICAL PRACTICES, WHICH YOU COULD NOT OBTAIN WITH THE CLASSIC METHOD
In 2006 the International Organization of Vine and Wine (OIV) replaced and downgraded the “classic” method based on the measurement of absorbance at three wavelengths with the CIELab method, which has therefore become the reference method (of TYPE 1) for the analysis of the wine color.
BUT WHY THE CIELAB METHOD IS SO IMPORTANT?
Classic method vs. CIELab method
⇒ uses the 3 wavelengths 420-520-620 nm.
It is not the real measure of color but an approximate method to obtain indications of intensity and tone.
Although incomplete, this method has been used, and is still used, as a measure of color both for the simplicity of the method and for the interpretation of the data, and for a technological limitation of the most used tools.
Standard method coefficients:
- Intensity = A420 + A520 + A620
- Tone = A420 / A520
⇒ uses 80 wavelengths between 380 and 780 nm.
It is the representation of color closest to human perception.
Using specific algorithms that simulate the behavior of the human eye, the 80 wavelengths are transformed into three coefficients C, H and L which uniquely and objectively represent the chromatic characteristics of each wine sample.
CIELab method coefficients:
- a = red/green, b = yellow/blue
- Chroma = (a2 + b2)1/2
- Heu = arctan(b/a)
- L = degree of lightness
The advantages of the CIELab method compared to the “standard” one:
• it provides true color analysis using the entire visible spectrum between 380 – 780 nm
• it allows to uniquely and objectively distinguish the chromatic characteristics of the wine
• it is the latest international colorimetry standard (CIE) and is the representation of color closest to the perception of the human eye
• it allows an easy numerical and graphical representation of the color
CIELAB MEASUREMENTS WITH SMART ANALYSIS
The measurements and the results reported in the article were obtained with the Smart Analysis technology, which allows the color analysis with CIELab in an extremely simple and rapid way, with a simple click!
Fill out the form to receive the article by the University of Florence about the use on CIELab in the cellar