Wine Chemistry and Biochemistry

696 P.J. Mart ́ın-Alvarez ́

Table 13.14Results of applying principal components analysis to the 10 volatilecompounds ana-
lyzed in 16 varietal wines. Factor loadings matrix:

PC1 PC2

Methanol –0.707∗ 0.375

1-Propanol 0.870∗ 0.193

Isobutanol –0.634 0.334

Isoamylic alcohols –0.590 0.720∗

1-Hexanol –0.885∗ –0.126

cis-3-Hexen-1-ol –0.888∗ –0.228

Hexanoic acid 0.589 –0.569

Octanoic acid –0.861∗ –0.438

Decanoic acid –0.507 –0.793∗

Ethyl octanoate 0.103 –0.242

∗Loadings>0.7

Explain variance 4.935 2.078

Proportion total 0.493 0.208

Table 13.15Results of applying principal components analysis to the 10 volatilecompounds ana-
lyzed in 16 varietal wines. Scores for the samples:

PC1 PC2

Ma98 1.543 –0.539

Ma98 1.462 –0.537

Ma99 0.891 0.453

Ma99 0.695 0.358

Ai97 0.669 0.639

Ai97 0.422 0.940

Ai98 0.526 0.160

Ai98 0.408 0.493

Tr97 –1.644 –0.003

Tr97 –1.807 –0.163

Tr98 –0.581 –1.808

Tr98 –0.735 1.328

Mo97 –0.419 –2.188

Mo97 –1.015 1.560

Mo98 –0.221 –0.409

Mo98 –0.195 –0.286

Applications

As an example, Tables 13.14 and 13.15 show the results of applying principal com-

ponents analysis to the 10 volatile compounds(methanol, 1-propanol, isobutanol, 2-

and 3-methyl-1-butanol, 1-hexanol,cis-3-hexen-1-ol, hexanoic acid, octanoic acid,

decanoic acid and ethyl octanoate) analyzed in 16 varietal wines (Pozo-Bay ́on

et al. 2001), obtained with the STATISTICA program (Factor Analysisproce-

dure inMultivariate Exploratory Techniquesmodule, and using Principal Compo-

nents as Extraction method). The results include: the factor loadings matrix for

the two first principal components selected (q = 2), which explains 70.1% of

the total variance (Table 13.14). The first principal component is strongly corre-

lated withcis-3-hexen-1-ol (–0.888), 1-hexanol (–0.885), 1-propanol (0.870), and