aroma as will be shown in the next section. This is an interesting
result that reveals the applicability of this system to fraud control.
In order to discard the influence of the pure ethanol standard on
the results presented above, an alternative PCA plot was obtained
excluding the sensor response to this compound from the data pro-
cessing process. The corresponding PCA distribution is shown in
Fig. S1 (see Supplementary Information). As shown in this figure,
the PCA plots obtained from both the method (a), top graph, without
removing ethanol from the samples, and the method (b), bottom
graph, are very similar to that provided in Fig. 4, leading to the same
conclusions regarding the discrimination ability of the used system
and methods.