title: Discrimination of Apple Liqueurs (Nalewka) Using a Voltammetric Electronic Tongue, UV-Vis and Raman Spectroscopy.
abstract: The capability of a phthalocyanine-based voltammetric electronic tongue to analyze strong alcoholic beverages has been evaluated and compared with the performance of spectroscopic techniques coupled to chemometrics.NalewkaPolish liqueurs prepared from five apple varieties have been used as a model of strong liqueurs. Principal Component Analysis has demonstrated that the best discrimination between liqueurs prepared from different apple varieties is achieved using the e-tongue and UV-Vis spectroscopy. Raman spectra coupled to chemometrics have not been efficient in discriminating liqueurs. The calculated Euclidean distances and the k-Nearest Neighbors algorithm (kNN) confirmed these results. The main advantage of the e-tongue is that, using PLS-1, good correlations have been found simultaneously with the phenolic content measured by the Folin-Ciocalteu method (R² of 0.97 in calibration and R² of 0.93 in validation) and also with the density, a marker of the alcoholic content method (R² of 0.93 in calibration and R² of 0.88 in validation). UV-Vis coupled with chemometrics has shown good correlations only with the phenolic content (R² of 0.99 in calibration and R² of 0.99 in validation) but correlations with the alcoholic content were low. Raman coupled with chemometrics has shown good correlations only with density (R² of 0.96 in calibration and R² of 0.85 in validation). In summary, from the three holistic methods evaluated to analyze strong alcoholic liqueurs, the voltammetric electronic tongue using phthalocyanines as sensing elements is superior to Raman or UV-Vis techniques because it shows an excellent discrimination capability and remarkable correlations with both antioxidant capacity and alcoholic content-the most important parameters to be measured in this type of liqueurs.
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, Gdansk University of Technology, Narutowicza St. 11/12, 80-233 Gdańsk, Poland. m.e.sliwinska@gmail.com.|Department of Inorganic Chemistry, Engineers School, Universidad de Valladolid, 47011 Valladolid, Spain. m.e.sliwinska@gmail.com.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Śliwińska
authors.affiliation: Department of Inorganic Chemistry, Engineers School, Universidad de Valladolid, 47011 Valladolid, Spain. celiagarciahernandez@gmail.com.
authors.forename: Celia
authors.initials: C
authors.lastname: Garcia-Hernandez
authors.affiliation: The NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland. mikolaj.koscinski@amu.edu.pl.
authors.forename: Mikołaj
authors.initials: M
authors.lastname: Kościński
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, Gdansk University of Technology, Narutowicza St. 11/12, 80-233 Gdańsk, Poland. tomasz.dymerski@gmail.com.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Dymerski
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, Gdansk University of Technology, Narutowicza St. 11/12, 80-233 Gdańsk, Poland. walwarde@pg.gda.pl.
authors.forename: Waldemar
authors.initials: W
authors.lastname: Wardencki
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, Gdansk University of Technology, Narutowicza St. 11/12, 80-233 Gdańsk, Poland. jacek.namiesnik@pg.gda.pl.
authors.forename: Jacek
authors.initials: J
authors.lastname: Namieśnik
authors.affiliation: The NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland. msb@amu.edu.pl.|Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland. msb@amu.edu.pl.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Śliwińska-Bartkowiak
authors.affiliation: The NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland. stjurga@amu.edu.pl.
authors.forename: Stefan
authors.initials: S
authors.lastname: Jurga
authors.affiliation: Department of Materials Science, Engineers School, University of Valladolid, Valladolid 47011, Spain. crigar@eii.uva.es.
authors.forename: Cristina
authors.initials: C
authors.lastname: Garcia-Cabezon
authors.affiliation: Department of Inorganic Chemistry, Engineers School, Universidad de Valladolid, 47011 Valladolid, Spain. mluz@eii.uva.es.
authors.forename: Maria Luz
authors.initials: ML
authors.lastname: Rodriguez-Mendez
keywords: Raman spectroscopy; UV-Vis; apple liqueurs; electronic tongue; nalewka; voltammetric sensor