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Discrimination of Port Wine categories based on analytical
parameters: retrospective study
M. L. Ferreira 1,2 , L. M. Cunha 2, 3 and J. Queiroz 2,3
1 Instituto dos Vinhos do Douro e do Porto, I.P., Porto, Portugal
2 MSc. Agricultural Engineering, Faculty of Sciences, University of Porto, Rua Padre Armando
Quintas, 7, 4485-661 Vairão, Portugal.
3 GRESA, Associated Laboratory REQUIMTE, University of Porto, Portugal.
The purpose of this work was to characterize different categories of Port Wine according to
analytical parameters that are usually determined under the certification of Port Wines, carried
out in the Instituto dos Vinhos do Douro e do Porto, I.P. (IVDP - Douro and Port Wines
Institute). For this purpose, analytical data from 2000 to 2008 were obtained from the IVDP’s
database, which, after a description of the data structure, were subsequently treated applying a
multivariate statistical approach: Discriminant Analysis, bearing in mind that the main purpose
of a discriminant function analysis is to predict group membership based on a linear
combination of the interval variables. Data regarding 18 analytical parameters from 620
randomly selected bulletins of previously evaluated Port Wines were used. For each of the two
major Port Wine styles: (i) wines with oxidative ageing (Tawny style) and (ii) wines with a
young character (Ruby style), this work allowed for the built up of statistical models,
permitting differentiation, with a high percentage of correctly classified wines (over 80 %), of
most categories belonging to either of those groups. Models were optimised through stepwise
procedure retaining 9 variables (analytical parameters) for classification of Tawny’s and 5
variables for classification of Ruby’s, reduced to two dimensions explaining 98.9 % and 100 %
of the data variability, respectively.
Acknowledgments:
Authors acknowledge the support given by the Direction of IVDP, I.P. that has provided the use of
analytical data from the Institute’s database for this study. M. L. Ferreira acknowledges the contribution
given by Ana Faria, Bento Amaral, Natália Ribeiro and Tomás Simões from the IVDP, I.P., through
thoughtful discussions during the evolution of this research project.
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