Comparison of several chemometric techniques for the classification of orujo distillate alcoholic samples from Galicia (northwest Spain) according to their certified brand of origin

Abstract

This paper has a double objective. The first goal was to develop an authentication system to differentiate between traditional orujo alcoholic distillates with and without a certified brand of origin (CBO). Owing to their low price and quality, samples without a CBO can be used as substrates for falsification of genuine CBO ones. The second objective was to perform a comparison of the abilities of the different chemometric procedures employed for this classification. The classification was performed on the basis of the chemical information contained in the metal composition of the orujo distillates. Eight metals determined by electrothermal atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry were considered (Ca, Cd, Cr, Cu, K, Mg, Na and Ni). After the appropriate pretreatment, the data were processed using different chemometric techniques. In the first stage, principal component analysis and cluster analysis were employed to reveal the latent structure contained in the data. Once it had been demonstrated that a relation exists between the metal composition and the raw materials, and not between the metal composition and the distillation systems employed for the orujo production, the second step consisted in the comparative application of different supervised pattern recognition procedures (such as linear discriminant analysis, K-nearest neighbours, soft independent modelling of class analogy, UNEQ and different artificial neural network approaches, including multilayer feed-forward, support vector machines, learning vector quantization and probabilistic neural networks). The results showed the different capabilities of the diverse classification techniques to discriminate between Galician orujo samples. The best results were those provided by probabilistic neural networks, in which the correct recognition abilities for CBO classes and without CBO classes were 98.6 +/- 3.1 and 98.0 +/- 4.5%; the prediction results were 87.7 +/- 3.3 and 86.2 +/- 5.0%, respectively. The usefulness of chemical metal analysis in combination with chemometric techniques to develop a classification procedure to authenticate Galician CBO orujo samples is demonstrated.

Rapid Determination of Trace Elements in Macedonian Grape Brandies for Their Characterization and Safety Evaluation

“…Trace element concentration in distillates produced around the world (brandy, cognac, rum, and whisky) is a significant parameter with a positive or negative effect on the quality of the final product (Green et al 1997;Ibanez et al 2008;Rodriguez et al 2010;Ivanova-Petropulos et al 2013;Rodríguez-Solana et al 2014). From nutritional and toxicological points of view, elements are classified into essential and non-essential.…”

“…The sources of metals in alcoholic beverages are multiple including raw materials, vessels used during fermentation, distillation equipment, added substances during brewing, bottling process, aging/storage, and adulteration (Rodriguez et al 2010;Rodríguez-Solana et al 2014;Ivanova-Petropulos et al 2015). Therefore, information about the content of metals in brandies is of great importance for producers and consumers for their health protection against toxic elements, as well as for the government authorities in order to guarantee the quality of the own traditional product.…”

“…Sensitive techniques, such as flame atomic absorption spectrometry (FAAS), graphite furnace atomic absorption spectrometry (GFAAS), atomic fluorescence spectrometry (AFS), inductively coupled plasma-optical emission spectrometry (ICP-OES), inductively coupled plasma-mass spectrometry (ICP-MS), and potentiometric and voltammetric methods, are required for accurate determination of metals in various samples (Mena et al 1997;Onianwa et al 1999;Karadjova et al 2002;Ibanez et al 2008;Rodriguez et al 2010;Ivanova-Petropulos et al 2013;Ly et al 2013;FroesSilva et al 2015;Seeger et al 2015). Analysis is performed directly on undiluted samples, after a water dilution, or after digestion in open/closed vessel systems with HNO 3 , HCl, H 2 O 2 , or their mixtures.…”

Comparison of Chemometric Problems in Food Analysis using Non-Linear Methods

“…Chemical information found in metal composition of the orujo distillates was used for development of a system for discrimination between alcoholic distillates with certified brand of origin (CBO) and those without CBO. In comparison between methods, classification accuracy of PNN exceeds that of other techniques such as SVM, resulting in classification accuracies of 98.6 ± 3.1% and 98.0 ± 4.5% for COB and non-COB distillates [155]. Classification of white and rested tequilas was done using SVM on a sample set consisting of 80 bottles with 39 white and 42 rested types classified into 4 sets of white and 4 sets of rested tequilas for a total of 8 groups.…”

Analysis of HPLC fingerprints: discrimination of raw and processed Rhubarb samples with the aid of chemometrics

“…22 The method is based on the determination of linear discrimination functions, which enable the grouping of objects such that the ratio of between-class variance is maximized and the ratio of within-class variance is minimized. 23 Like PCA, LDA is a feature reduction method but while PCA retains maximum data structure in a low dimensional space, LDA models seek a maximum separation among the different classes.…”