ABSTRACT
An important aspect of assessing the authenticity of wines is its geographical origin. The aim of the work is to authenticate by geographical origin according to the data of the ICP-spectrometric and chemometric analysis of elemental "images" of wines produced from white grape varieties Chardonnay, Riesling and Muscat grown in four regions of the Krasnodar Territory, Russia. The difference in the contents of Al, Ba, Ca and Rb in wines was found depending on the variety, and Al, Ba, Rb, Fe, Li, Sr - depending on the region of grape growth. Different models of the experimental data processing were used for attribution of the produced varieties of wine to the area of the grape's growth. The criterion for the quality of the constructed models was the accuracy of the attribution of a wine variety to the area of the grape's growth (%). Analysis of the elemental analysis data of 153 wine samples showed that in terms of attribution accuracy, automated neural networks (100 %) are preferred among machine learning methods, followed by support vector machines (98.69 %) and general discriminant analysis (94.77 %). The applied mathematical models enabled the revealing of the cluster structure of the analyzed wine varieties and their attribution to the area of a grape growth with high accuracy. Sr, Li and Fe concentrations in wines were found as the dominating predictors in the constructed models for definition of the geographical origin of wines. The combination of ICP-spectrometric analysis data with the capabilities of statistical modeling of machine learning methods focused on large-dimensional data made it possible to successfully solve small-dimensional problems of the definition of the geographical origin of wines by their elemental composition and variety.
ABSTRACT
The possibility of establishing the varietal and territorial affiliation of wines by the content of rare earth elements (REE) in them was studied. ICP-OES and ICP-MS with subsequent chemometric processing of the results were applied to determine the elemental image of soils containing negligible REE amounts, grapes grown on these soils, and wine materials of Cabernet Sauvignon, Merlot, and Moldova varieties produced from these grapes. To stabilize and clarify wine materials, the traditional processing of wine materials with various types of bentonite clays (BT) was used, which turned out to be a source of REE in the wine material. Discriminant analysis revealed that the processed wine materials were homogeneous within one denomination and that those of different denominations were heterogeneous with respect to the content of REE. It was found that REE in wine materials were transferred from BT during the processing, and thus they can poorly characterize the geographical origin and varietal affiliation of wines. Analysis of these wine materials according to the intrinsic concentrations of macro- and microelements showed that they formed clusters according to their varietal affiliation. In terms of their influence on the varietal image of wine materials, REE are significantly inferior to macro- and microelements, but they enhance their influence to a certain extent when used together.
Subject(s)
Metals, Rare Earth , Vitis , Wine , Wine/analysis , Discriminant Analysis , Metals, Rare Earth/analysis , GeographyABSTRACT
The content of free amino acids and aroma compounds present in wine and dependent on the grape variety, conditions of its growing and technology of production form its consumer properties. In this paper, the structure of interactions of amino acids and volatile organic compounds in 150 samples of natural dry red and white wines produced in the Krasnodar region, Russia, (2010-2013) was studied. The aim of this work was to comparatively evaluate the contribution of volatile compounds and amino acids to the sensory properties of wines by using regression, canonical, covariance, factor analyses, as well as principal component analysis. The list of volatile compounds, i.e., acetaldehyde, ethyl acetate, methanol, the total content of higher alcohols, acetic acid, and furfural, and such amino acids as arginine, proline, threonine was selected based on their influence on sensory properties of wines. The concentrations of volatile compounds and amino acids in wines were determined by gas chromatography and capillary electrophoresis, respectively. Sensory evaluation was conducted by experts with professional experience in wine tasting. Application of statistical methods allowed to establish intra- and inter-group correlations among amino acids and volatile compounds as well as between the groups of these compounds, which determined sensory properties of wines. More than 80% of the variability of the sensory assessment of wines is determined by the degree of relationship between the selected amino acids and volatile compounds; the contribution of amino acids to this indicator is 4.5-fold higher. The results obtained can be used to predict the sensory assessment of red and white wines based on the levels of volatile compounds and amino acids.
