Macrowine 2021
IVES 9 IVES Conference Series 9 Colour assessment of port wines using colorimetric and spectrophotometric methods

Colour assessment of port wines using colorimetric and spectrophotometric methods

Abstract

Colour is an important quality parameter in wines and is the result of a complex mixture of pigments (including anthocyanins and their derivatives, quinones, xanthyllium compounds, etc.). Red wine colour changes over time as pigments react between themselves and with other wine macromolecules (particularly polyphenols). During wine tasting, colour is normally assessed on the outer rim of the wine profile in a tilted glass, since most wines are too opaque to be analysed in the middle of the glass. Therefore, depending on the depth of observation considered, the perception of wine colour can be different. The precise measurement of wine colour is usually done using molecular (UV-VIS) spectrophotometric methods. In the current official (OIV) method, the transmittance spectrum of a particular sample is measured and used to calculate CIE L*a*b* parameters, which define a single (predominant) colour for a particular wine. Reflectance colorimetry is an alternative well-established method for measuring colour in foodstuffs, which can also be used in transparent samples (such as wines) as long as a reflective background is used. In this work, a reflectance colorimeter was used to measure CIE L*a*b* colour parameters of Port wine samples of different categories at different depths, in Petri dishes. The obtained results were compared with the parameters obtained using the OIV method. Representative profiles of Lightness (L*), Hue (H*) and Chroma (C*) vs. wine depths were obtained using Port wine samples from different categories and ages. Wines from the same category exhibited similar colour (depth) profiles, with Tawny-styled wines showing a more linear profile than Ruby-styled wines regarding the L* and H* parameters. Good correlations between the colorimetric and OIV methods were obtained for the L* (Ruby:R >= 0.97; Tawny:R > 0.86) and H* parameters (Ruby:R >= 0.90; Tawny >= 0.91) with the C* parameter giving inferior results, particularly in Tawny-style wines (Ruby:R >= 0.87; Tawny >= 0.29). The results suggest the colorimetric method can be used as an alternative to the OIV method for estimating the L* and H* parameters (the most important for wine colour definition), being quicker and more informative.

Publication date: May 17, 2024

Issue: Macrowine 2016

Type: Poster

Authors

Francisco Silva*, Bento Amaral, Cristina Silva, Francisco Campos, Manuel Ferreira, Natalia Ribeiro, Tomas Simões

*Escola Sup. Biotecnologia – UCP

Contact the author

Tags

IVES Conference Series | Macrowine | Macrowine 2016

Citation

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