Tunisian olive oils geographical origin discrimination using the potentiometric fingerprints recorded by an electronic tongue
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resumo
The development of fast and cost-effective
analytical techniques for EVOO authentication
is a challenging task. Moreover, if a specific
meteorological or geographical factor affects
different geographical regions similarly, olive oils
geographical discrimination may be a hard task using
conventional analytical techniques [1]. E-noses
and/or voltammetric E-tongues have already been
applied to assess olive oils' geographical origin,
mainly to discriminate different countries or quite
different regions of the same country [2].
In this work, we used an electronic tongue
(E-tongue ), with 40 lipid membrane sensors, to
extract representative potentiometric fingerprints of
Tunisian monovarietal olive oils that, in combination
with linear discriminant analysis (LOA), could
be used to classify olive oils according to the
geographical origin. Aqueous ethanolic (80:20, v/v)
extracts of different single-cultivar Tunisian olive
oils were electrochemically analysed. According to
the literature [3-6], these olive oil' extracts are rich
in polar compounds that deliver different overall
potentiometric responses, which can then be used
to evaluate the E-tongue performance for olive oils
geographical origin discrimination. The proposed
E-tongue-LDA approach, based on the signal
profiles of different sub-sets of sensors (seleted
with the simulated annealing meta-heuristic algorithm) allowed the correct geographical origin
classification of Tunisian olive oils produced from
autochthonous Chemleli or Sahli cultivars (i.e.,
Kairouan, Sidi Bouzid and Sfax; or, Mahdia, Sousse
and Kairouan; respectively). Indeed, predictive
correct classifications of 92±7% and 97±8%
(for repeated K-fold cross-validation) could be
obtained for Chemleli or Sahli olive oils, pointing
out the potential use of the E-tongue device for
geographical origin identification of olive oils.
The development of fast and cost-effective analytical techniques for EVOO authentication is a challenging task. Moreover, if a specific meteorological or geographical factor affects different geographical regions similarly, olive oils geographical discrimination may be a hard task using conventional analytical techniques [1]. E-noses and/or voltammetric E-tongues have already been applied to assess olive oils' geographical origin, mainly to discriminate different countries or quite different regions of the same country [2].
