Christos Tsolakis

Effects of area, year and climatic factors on Barbera wine characteristics studied by the combination of 1H-NMR metabolomics and chemometrics

ABSTRACT Barbera is one of the most common red grape in Italy, found in almost every region of the country. The widespread market of the corresponding wine deserves studies on its traceability and authenticity. To this end, the 1H-NMR database of several wine metabolites was built using spectra recorded in a wine-like matrix containing ethanol and tartaric acid with pH precisely adjusted. The combination of 1H-NMR metabolomics study and chemometrics (multivariate data analysis) is able to discriminate between samples of such a wine produced in three different areas of Piedmont. The influence of climatic factors on the wine characteristics has also been studied.

Influence of early seeds removal on the physicochemical, polyphenolic, aromatic and sensory characteristics of red wines from Gaglioppo cv .

The technique of seeds removal during the fermentative maceration was conceived to limit the extraction of polyphenols from the seeds in order to reduce the natural wine astringency. The influence of this oenological practice on the polyphenolic composition of Gaglioppo wines was studied during three vintages (2010–2012): the wines produced in the presence (WS) or absence (WOS) of seeds were compared for the physicochemical, polyphenolic and volatile composition, as well as for the sensory characteristics. Seeds removal did not cause any important modification in the general physicochemical composition of wines. Regarding polyphenols, no differences in total anthocyanins content were observed between the trials, but a significantly lower total polyphenols content was observed in the WOS wines, regarding in particular total flavonoids, low molecular weight flavans and condensed tannins. Qualitative variations in the composition of condensed tannins were also observed: the WOS wines had a higher mean degree of polymerization (mDP) and a lower galloylation degree. Finally, minor differences in the aromatic profile due to the seeds removal technique were observed between the trials. Despite the important modifications of the polyphenolic composition, the sensory characteristics of the wines, on the whole, were not affected: a significant decrease of the bitter taste in the WOS trial was noticed only in vintage 2010.

Antioxidant Composition of a Selection of Italian Red Wines and Their Corresponding Free-Radical Scavenging Ability

This study correlates the antioxidant composition profiles and the overall antioxidant capacities of 36 Italian red wine samples. The samples were fully characterized by chromatographic and spectrophotometric techniques. The overall antioxidant capacity was determined by titrating a solution of the semistable free radical DPPH (1,1-diphenyl-2-picrylhydrazyl) with each wine sample followed by Electron Paramagnetic Resonance (EPR) spectroscopy and then measuring the resulting decrease in DPPH-signal. The antioxidant activities of the samples were expressed as (

Wine evolution during bottle aging, studied by 1H NMR spectroscopy and multivariate statistical analysis

The study of wine evolution during bottle aging is an important aspect of wine quality. Ten different red wines (Vitis vinifera) from Piedmont region were analysed 3 months after bottling and after a further 48 month conservation in a climate controlled wine cellar kept at a constant/controlled temperature of 12 °C. Two white wines (Vitis vinifera) were included in this study for comparison purposes. White wines were analysed 3 months after bottling and after further 24 months of bottle aging in the same climate controlled wine cellar. Metabolite changes during this period were evaluated using 1H NMR spectroscopy combined with statistical analysis. Metabolite variations due to wine aging were minimal compared to those that resulted from a different wine type and wine geographical origin. Therefore, it was necessary to remove this source of variability to discriminate between fresh and refined samples. The storage at low and controlled temperature for 2 or 4 years permitted a slow but progressive evolution of all wines under investigation. 1H NMR spectroscopy, implemented with statistical data analysis, allowed identifying and differentiating wine samples from the two aging stages. In most wines, a decrease in organic acids (lactic acid, succinic acid and tartaric acid) and an increase in esters (ethyl acetate and ethyl lactate) was observed. Catechin and epicatechin decreased during aging in all wines while gallic acid increased in almost all red wines.

Managing wine quality using Torulaspora delbrueckii and Oenococcus oeni starters in mixed fermentations of a red Barbera wine

The use of selected starter cultures for grape must fermentation is nowadays practiced in most wine regions of the world, and as the range of available microorganisms increases this gives winemakers the possibility to increase biodiversity in guided fermentations. Nevertheless, little information is available regarding the oenological use of Saccharomyces and non-Saccharomyces yeasts in combination with lactic acid bacteria. The present study evaluates the effect of the inoculation of a non-Saccharomyces yeast, Torulaspora delbrueckii, in an alcoholic fermentation (in combination with a Saccharomyces starter), together with different modalities of malolactic fermentation management (co-inoculation, sequential inoculation and no inoculation of an Oenococcus oeni starter), on the quality of a red Barbera wine. The fermentation dynamics were verified and the final wine properties were evaluated in terms of physico-chemical composition determined by 1H-NMR, free volatile compounds measured by GC-MS and organoleptic characteristics assessed via sensory analysis. Overall, the results show that the joint employment of non-Saccharomyces yeasts did not delay alcoholic nor malolactic fermentation progress, did not interfere with the positive effect of the co-inoculation of malolactic bacteria (beneficial for both fermentation length and for the chemical, aromatic and sensory properties of wine) and enabled the production of wines with a more intense colour.