ANALYSIS OF AGING AND TYPIFICATION OF VINTAGE PORTS BY PARTIAL LEAST-SQUARES AND SOFT INDEPENDENT MODELING CLASS ANALOGY

Vintage port is a wine produced in very limited amounts in the Portugu ese region of the Douro Valley. It ages very slowly in bottles and few analytical data are available, Thus, the composition of 24 wines from the cellars of Dow's and Graham's, corresponding to 12 different yea rs between 1963 and 1990, was analysed, Forty-one analytical parameter s determined on each sample were used to predict the year using a part ial least squares (PLS) regression and to identify the cellar using a soft independent modelling class analogy (SIMCA) model, Both problems fall naturally within the field of food chemometrics and present the s tatistical difficulty of having fewer objects than variables. It is, t herefore, impossible to apply normal multiple regression and discrimin ant analysis techniques, The PLS model requires two latent variables a nd explains 97.4% of the variance of the age variable and 90.2% of the cross-validated variance. As for the characterization of both brands, a SIMCA model with two components for each model correctly classified 22 of the 24 samples; it gives a sensitivity of 83.3% and a specifici ty of 91.7% for Dow's vintage ports, whereas for Graham's vintage port s the sensitivity and specificity are 91.7 and 100%, respectively.