One of the most important issues in the wine sector and prevention of adulterations of wines are discrimination of grape varieties, geographical origin of wine, and year of vintage. In this experimental research study, UV-Vis and FT-IR spectroscopic screening analytical approaches together with chemometric pattern recognition techniques were applied and compared in addressing two wine authentication problems: discrimination of (i) varietal and (ii) year of vintage of red wines produced in the same oenological region. UV-Vis and FT-IR spectra of red wines were registered for all the samples and the principal features related to chemical composition of the samples were identified. Furthermore, for the discrimination and classification of red wines a multivariate data analysis was developed. Spectral UV-Vis and FT-IR data were reduced to a small number of principal components (PCs) using principal component analysis (PCA) and then partial least squares discriminant analysis (PLS-DA) and linear discriminant analysis (LDA) were performed in order to develop qualitative classification and regression models. The first three PCs used to build the models explained 89% of the total variance in the case of UV-Vis data and 98% of the total variance for FR-IR data. PLS-DA results show that acceptable linear regression fits were observed for the varietal classification of wines based on FT-IR data. According to the obtained LDA classification rates, it can be affirmed that UV-Vis spectroscopy works better than FT-IR spectroscopy for the discrimination of red wines according to the grape variety, while classification of wines according to year of vintage was better for the LDA based FT-IR data model. A clear discrimination of aged wines (over six years) was observed. The proposed methodologies can be used as accessible tools for the wine identity assurance without the need for costly and laborious chemical analysis, which makes them more accessible to many laboratories.

The phenolic composition of wine is mostly determined by the accumulation of the phenolic compounds in the grapes, as well as their extraction into wine. To increase their concentration in grapes, yield reduction is usually performed by pruning, while to increase the extraction in wines, the maceration on skins is extended for longer periods of time. The present study focuses on the possibilities to apply both strategies to improve the polyphenol composition of organic red wines of Romanian variety ‘Fetească neagră’, which stands to benefit more from technological interventions than other varieties, which naturally accumulate higher phenol concentrations in the grapes. In the vineyard three experimental pruning variants were made, with 20, 28 and 36 buds/vine, while for wine, maceration was performed for either 8 or 16 days for each grape variant. The phenolic profiles of wines were determined by HPLC methods. The main anthocyanidins, such as malvidin, petunidin, delphinidin, peonidin and cyanidin, as well as the acylated and coumaroylated derivatives of malvidin and peonidin were quantitatively determined. Some other phenolic compounds, of various classes, such as gallic, p-benzoic, p-coumaric and ferulic acid, catechin, epicatechin, myricetin, quercetin and trans-resveratrol were also determined. The quality of the organic ‘Fetească neagră’ wines depended highly on the vintage, but yield reduction and the extension of skin maceration duration were especially beneficial in the less favourable year, when classical technologies lead to less accumulation of sugars, colour and other polyphenols. Concomitant application of both strategies led to the best results, irrespective of the year.

The objective of this study was to determine the influence of chitosan treatments, applied in vineyard for plan protection, on the phenolic quality of grapes. The study was conducted for two consecutive years (2020-2021) in the wine center of Murfatlar, Romania, on ‘Fetească neagră’, an ancient but well-known indigenous Romanian grape variety for red wines. Chitosan is meant to offer an alternative for the classic treatment with Bordeaux mixture (BM), which represented the control variant. A combination treatment with half dose of chitosan and half dose of BM was also applied and evaluated. Chemical composition at harvest time was evaluated by measuring the content of sugar, total acidity, pH, total anthocyanin potential (A_pH1), anthocyanins extractable at wine pH (A_pH3.2), total polyphenol index, skin tannins, seed tannins and seeds maturity. In wines the colour parameters were determined by spectrophotometry and individual phenolic compounds by UHPLC-HRMS. In grapes, accumulation of anthocyanins increased with the total dose of chitosan applied in the vineyard, with higher values in 2020 when temperatures were higher and the rainfall values were typical for the region. Accumulation of tannins in grape skins followed a similar trend. In wine, chitosan determined a significant 72% increase in colour intensity in 2020. Among the individual phenols gallic acid was predominant, with higher values in the rainier year (2021) and significant increases determined by chitosan treatment (especially in 2021 when it increased by 97% as compared to BM treatment). Catechin and epicatechin recorded important increases in the less favourable year (2021), with confirmed increases in both years elicited by the chitosan. Quercetin and myricetin were not influenced by the chitosan treatment, but their increase was correlated with higher temperatures and inversely correlated to the amount of rainfall. Trans-resveratrol ranged between 4.3-8.0 mg L^-1 in 2020 and 5.0-6.5 mg L^-1 in 2021, with an important increase determined by the chitosan treatment in 2020 (89% increase compared to BM treatment).

Grape pomace, a by-product of the winemaking process, is a source of valuable natural compounds

As compared to red wine technology, where pomace is macerated, the grape juices and musts are obtained by pressing the grapes and removing the pomace, thus removing an important source of antioxidant molecules. The objective of this study was to exploit the bioactive compounds from the black grape pomace and obtain a new food product, namely pasteurized red must with improved health-promoting properties. The study was conducted on four grape varieties for red wines—Fetească Neagră, Cabernet Sauvignon, Blauer Zweigelt, and Arcaș—each coming from a certain recognized Romanian vineyard, as follows: Murfatlar, Dealu Mare, Ștefănești-Argeș, and Iași, respectively. Both the must and the pomace extract used for each product were from the same variety and region. The recovery of polyphenols was achieved by macerating the pomace at ambient temperature, using solutions of ethanol in concentrations of 25%, 50%, and 75%. The results showed that the most efficient method of polyphenol recovery was obtained by using the ethanolic solution of 50%, which was selected for the subsequent stages of the study. The selected hydroalcoholic extract was concentrated by eliminating the solvent by roto evaporation and used as a source of supplementary bioactive compounds for the pasteurized must. The phenolic profiles of the musts enriched with phenolic extracts were determined by liquid chromatography, UHPLS-HRMS, revealing significant increases in the content of individual phenolic acids and other polyphenols. The phenolic extract recovered from the pomace significantly optimized the phenolic quality of the pasteurized must, thus contributing to the improvement of its nutritional value. The new product has a phenolic profile close to that of a red wine, but does not contain alcohol. Also, this technology is a sustainable method to convert grape waste into a safe, antioxidant-rich grape juice with potential health benefits.