Author(s): Silva, Francisco A. G. Soares ; Campos, Francisco M. ; Ferreira, Manuel L. ; Ribeiro, Natália ; Amaral, Bento ; Simões, Tomás ; Silva, Cristina L. M.
Date: 2016
Persistent ID: http://hdl.handle.net/10400.14/54948
Origin: Veritati - Repositório Institucional da Universidade Católica Portuguesa
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) [1]. 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 [2;3;4]. 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 CIELab parameters (L*,a* and b*), 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 study, a reflectance colorimeter was used to measure CIELab 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.
