Vakare Merkyte

Environmental conditions such as vibrations, temperature, and exposure to light can lower the quality of bottled wine, causing great economic and image losses for wineries. Even under optimal storage conditions, environmental microvibrations can be a constant source of energy transfer to the stored bottles, and little is known about their effects over time. In this study, the effects of microvibrations on a fine Pinot noir wine were evaluated over a storage period of one year under controlled conditions and compared with those obtained using natural magnetic levitation as a damping technique to reduce the power transmitted by the vibrations. The wines were subjected to the treatments according to the following experimental set-up: (A) wines not exposed to microvibrations, but to natural magnetic levitation; (B) wines placed on a shelf in contact with the floor, and exposed to microvibrations; (C) controls, a shelf in direct contact with the floor, without the application of microvibrations; (D) wines on a shelf with natural magnetic levitation and exposed to microvibrations. Phenolic and volatile compounds were not significantly different between treatments, which is in line with the reduced energy stress applied. In contrast, the storage time significantly influenced these chemical profiles. Through the sensory analysis performed after 0 and 12 months of storage, it was possible to distinguish the wines, as the overall quality improved, especially for the microvibration-treated samples. After 12 months of storage: (a) the overall sensory quality improved for all wines compared to the samples at T0; (b) the damping of microvibrations reduced the rate of wine evolution; (c) treatment with microvibration up to 6 months was useful for improving the quality of wine not yet ready for the market. Therefore, modulation of wine evolution can be achieved by applying a combination of microvibrations and their damping, depending on the enological objective.

Volatile and non-volatile chemical profiles, free and total SO₂ and dissolved oxygen content were studied in three red (Merlot, Lagrein red, St. Magdalener) and one rosé (Lagrein rosé) wine after 30 months of storage in bottles. Each wine was sealed with closures made of a ‘blend’ (B) of natural cork microgranules and polymers without glue and was compared with wines closed with other types of corks (C; a technical cork 1 + 1, or an agglomerated natural cork or a natural one-piece cork). Glutathionyl caftaric acid (GRP) was inversely correlated with total SO₂ content and was higher in all three red wines closed with B compared to C, whereas epicatechin was higher in three wines closed with C compared to B. Three volatile compounds formed by fermentation (ethyl butanoate, isoamyl lactate, and octanol) were inversely correlated with both free and total SO₂. In terms of their volatile profiles, ethyl octanoate and 2,3-butanediol were significantly higher in the Lagrein red wines closed with C closures, whereas no significant difference was observed in Merlot, Lagrein rosé and St. Magdalener wines. Small differences in some phenolic compounds due to the type of closure were found: GRP, syringic acid, (+)-catechin, and (−)-epicatechin differentiated the Merlot wines closed with B from the C closures. Protocatechuic acid and GRP levels differentiated the Lagrein red wines according to their closure type, whereas only (−)-epicatechin differentiated the Lagrein rosé wines. GRP, caffeic acid, (−)-epicatechin, and anthocyanin content differentiated the St. Magdalener wines according to their closure type. Even though St. Magdalener and Lagrein rosé closed with C could be distinguished from those closed with B by using the (sensory) triangle test (α = 0.05), these differences appeared to be relative as it did not include all the wines in a systematic manner.

Targeted and untargeted determinations are being currently applied to different classes of natural phenolics to develop an integrated approach aimed at ensuring compliance to regulatory prescriptions related to specific quality parameters of wine production. The regulations are particularly severe for wine and include various aspects of the viticulture practices and winemaking techniques. Nevertheless, the use of phenolic profiles for quality control is still fragmented and incomplete, even if they are a promising tool for quality evaluation. Only a few methods have been already validated and widely applied, and an integrated approach is in fact still missing because of the complex dependence of the chemical profile of wine on many viticultural and enological factors, which have not been clarified yet. For example, there is a lack of studies about the phenolic composition in relation to the wine authenticity of white and especially rosé wines. This review is a bibliographic account on the approaches based on phenolic species that have been developed for the evaluation of wine quality and frauds, from the grape varieties (of V. vinifera and non vinifera), to the geographical origin, the vintage year, the winemaking process, and wine aging. Future perspectives on the role of phenolic compounds in different wine quality aspects, which should be still exploited, are also outlined.

The identification of cyclic B‐type procyanidins in grape and wine was recently disclosed. Some of these were also found in berries of totally different vegetal species (eg, Vaccinium sp.). However, presence of a wider class of these cyclic condensed tannin compounds with variably substituted monomers has never been addressed so far. Here, an extended list of oligomeric cyclic proanthocyanidins (PAC) bearing variable substitution patterns on the main flavan‐3‐ol unit has been searched in wines. Nearly 7600 theoretical structures were calculated and searched in red and white wine samples made from different grape varieties. Moreover, a hydrogen/deuterium exchange approach (already applied to a cyclic tetrameric procyanidin) coupled to high‐resolution mass spectrometry was applied to confirm their cyclic B‐type structure rather than a non cyclic A‐type structure, otherwise isomeric and undistinguishable by LC‐MS alone. The main group of novel cyclic PAC observed is shown to contain (epi)gallocatechin beside (epi)catechin as the constituent monomers.

Rationale: Cyclic B‐type (referred also as crown) proanthocyanidins (PACs) were recently identified in wines. A high‐performance liquid chromatography/high‐resolution tandem mass spectrometry (HPLC/HRMS/MS) method was applied to study the binding of cyclic and non‐cyclic PACs to potassium and calcium ions, which affect the chemico‐physical stability of wines. Different binding affinities suggest that cyclic and non‐cyclic analogues, despite the equal number of monomer units, influence the colloidal stability of wine and are related to the grape variety or winemaking conditions. Methods: Nineteen red and white wines were analysed by HPLC/HRMS/MS with positive electrospray ionization to investigate the distribution of novel cyclic PACs and their calcium, potassium and sodium adducts. Principal components analysis was used to study the distribution of the wines and the relationships among PACs with and without cation complexes. Results: A dependence on specific isomers (and conformations) was found for the non‐cyclic procyanidin (PC) trimer whereas the cyclic tetrameric PACs were shown to bind better to potassium than their non‐cyclic analogues. The binding to these metals appeared to be influenced not only by the number of monomer units, but also by the conformation assumed by the molecules. Statistical analysis evidenced that the distribution of adducts in different wines is less influenced by the grape variety used for winemaking than their associated [M + H] ⁺ species studied earlier. Conclusions: Wines from 19 grape varieties were investigated in order to identify potassium and calcium complexes of non‐ and cyclic B‐type PACs that were recently discovered. The results showed a dependence of the distribution of metal complexes according to the cyclic or non‐cyclic geometry of PACs. The multivariate analysis of the mass spectrometric results showed a relationship with the grape variety; however, this was not as straightforward as evidenced for the non‐complexed species.

Hydrogen/deuterium exchange coupled with high-resolution mass spectrometry was successfully applied for the identification of A-type tetrameric, pentameric, and hexameric procyanidins in peanut skin. This extended a previous study on isomeric cyclic B-type unconventional tetramer, pentamer, and hexamer procyanidins found in wine and cranberries. Not only had the method successfully identified the procyanidins with a single A-linkage (e.g., tetrameric m/z 1153.2608) by means of distinguishing them from their isomeric cyclic B-type analogues, but this method also worked for procyanidins with two or more A-linkages (such as the tetrameric m/z 1151.2452). As a further consequence, B-type cyclic pentamers and hexamers in wine have been elucidated with hydrogen/deuterium exchange (HDX) for the first time.

The sensory properties, the phenolic composition, and the volatile profile of Chardonnay wine made in amphorae were compared with the wine obtained in large wooden barrels (2000 L) and small toasted barrels (225 L). Hierarchical cluster analysis and principal component analysis built on the phenolics and volatiles variables allowed to group effectively the samples according to the winemaking material used. In‐amphorae wines showed more abundant catechin and caffeic acid and less abundant caftaric acid and trans‐coutaric acid. Condensation reactions proceeded in the wood containers leading to esterification of organic acids with ethanol and alcohols, whereas in‐amphorae wines were characterized by a higher content of free phenolic acids and higher volatile alcohols. Among the volatile compounds, ramified ethyl esters contributed mostly in samples made in small toasted barrels, whereas nonbranched ethyl esters contributed more for the samples made in large wooden tanks; higher alcohols contributed more for the in‐amphorae wine. The sensory analysis showed negligible differences induced by the in‐amphorae vinification with respect to the wooden one. Four variables could distinguish wines made in‐amphorae compared with the other containers: solvent and acetone (SA), astringent/pungency (AP), fruity (FR), and color intensity (CI). The overall approach proposed here is promising for future developments of innovative types of Chardonnay wine blends.

An electronic tongue based on a flow injection system equipped with a multichannel amperometric detector was used to determine the antioxidant activity, total phenols and bitter taste of red wines. The detector composed of four glassy carbon electrodes, arranged in a square configuration, where two parallel electrodes (poised at E₁=+400 and E₂=+800 mV) were followed by other two electrodes (poised at E₃=+800 and E₄=−400 mV). This configuration allowed to gain information on the content of the antioxidants activity (E₁) and total phenols (E₂ and E₃). E₁/E₂ was used to express the proportion of strong vs. weak antioxidants. E₃/E₄ was used to express an index of reversibility. Finally, the ratio E₂/E₃ was used to control the system. Overall, the four electrodes led to seven variables, which provided a characteristic pattern profile. The eleven variables in total were analyzed by principal component analysis (PCA) to determine, the antioxidant activity, total phenol content and bitterness value of red wine samples. The results of antioxidant activity were correlated with the Folin Ciocalteu index (R²=0.94). Bitterness was correlated with the descriptors of the e‐tongue (R²=0.81). Overall, the analysis with the proposed electronic tongue is simple (only a dilution is required), fast (the analysis takes less than 20 seconds per sample), objective (precision within 5 %, expressed as RSD%) and cheap compared to classical sensory analysis.