1H-NMR Metabolomics as a Tool for Winemaking Monitoring

The chemical composition of wine is known to be influenced by multiple factors including some viticulture practices and winemaking processes. 1H-NMR metabolomics has been successfully applied to the study of wine authenticity. In the present study, 1H-NMR metabolomics in combination with multivariate analysis was applied to investigate the effects of grape maturity and enzyme and fining treatments on Cabernet Sauvignon wines. A total of forty wine metabolites were quantified. Three different stages of maturity were studied (under-maturity, maturity and over-maturity). Enzyme treatments were carried out using two pectolytic enzymes (E1 and E2). Finally, two proteinaceous fining treatments were compared (vegetable protein, fining F1; pea protein and PVPP, fining F2). The results show a clear difference between the three stages of maturity, with an impact on different classes of metabolites including amino acids, organic acids, sugars, phenolic compounds, alcohols and esters. A clear separation between enzymes E1 and E2 was observed. Both fining agents had a significant effect on metabolite concentrations. The results demonstrate that 1H-NMR metabolomics provides a fast and robust approach to study the effect of winemaking processes on wine metabolites. These results support the interest to pursue the development of 1H-NMR metabolomics to investigate the effects of winemaking on wine quality.

The effectiveness analysis of technological and biotechnological methods for production of dry wines from ‘Muscat Blanc’ grape variety

В статье рассматривается эффективность технологических и биотехнологических приемов при производстве сухих вин из винограда сорта Мускат белый. Показано, что предбродильная аэрация дрожжевой культуры приводит к формированию более окисленного фенольного комплекса виноматериалов. Значимым фактором формирования фенольного комплекса является режим сульфитации сусла: введение 75 мг/дм SO способствует увеличению содержания фенольных компонентов в виноматериалах в 1,5 раза по сравнению с несульфитированным суслом. Установлено, что штаммы дрожжей Ленинградская и Севастопольская 23 в процессе брожения синтезируют ацетальдегид в малых количествах; сульфитация сусла увеличивает содержание ацетальдегида в виноматериалах, полученных на культуре Севастопольская 23, в 1,6 раза. Показано, что в условиях длительного брожения сусла без доступа воздуха возрастает роль дрожжей в формировании терпеновых спиртов виноматериалов; обработка сусла оклеивающими препаратами способствует образованию терпенов дрожжами. По результатам органолептического тестирования виноматериалов определена совокупность приемов, позволяющих получать сухие виноматериалы из винограда Мускат белый с выраженным сортовым ароматом и вкусом. Эти приемы включают длительное брожение без доступа воздуха при температуре 16-18С с использованием расы дрожжей Севастопольская 23, сусла, сульфитированного до 75 мг/дм SO и обработанного оклеивающими препаратами - в случае традиционного виноделия; самоосветленного сусла без введения диоксида серы - в случае органического виноделия. The article considers the effectiveness of technological and biotechnological methods for production of dry wines from grapes of ‘Muscat Blanc’ variety. It is shown that pre-fermentation aeration of yeast culture leads to the formation of a more oxidized phenolic complex of base wines. A significant factor of phenolic complex formation is the process of must sulfiting: the introduction of 75 mg/dm of SO promotes to increasing the content of phenolic components in base wines by 1.5 times in comparison with unsulfited must. It is established that yeast strains ‘Leningradskaya’ and ‘Sevastopolskaya 23’ synthesize acetaldehyde in small quantities in the process of fermentation; must sulfiting increases the content of acetaldehyde in base wines obtained using culture ‘Sevastopolskaya 23’ by 1.6 times. It is shown that role of the yeast in the formation of base wine terpene alcohols increases under conditions of long anaerobic must fermentation; must processing with fining agents promotes to the terpene formation by the yeast. Based on the results of organoleptic base wine testing, a set of methods for obtaining dry base wines from grapes of ‘Muscat Blanc’ variety with a pronounced varietal aroma and flavor was determined. These methods include long anaerobic fermentation at a temperature of 16-18°C using the yeast race ‘Sevastopolskaya 23’, must sulfited to 75 mg/dm of SO and treated with fining agents - in case of traditional winemaking; self-clarified must without sulfur dioxide introduction - in case of organic winemaking.

Plant Fibers in Comparison with Other Fining Agents for the Reduction of Pesticide Residues and the Effect on the Volatile Profile of Austrian White and Red Wines

Pesticide residues in Austrian wines have so far been poorly documented. In 250 wines, 33 grape musts and 45 musts in fermentation, no limit values were exceeded, but in some cases high levels (>0.100 mg/L) of single residues were found, meaning that a reduction of these levels before bottling could make sense. In the course of this study, a white and a red wine were spiked with a mix of 23 pesticide residues from the group of fungicides (including botryticides), herbicides and insecticides. The influence of the following treatments on residue concentrations and volatile profiles were investigated: two activated charcoal products, a bentonite clay, two commercial mixed fining agents made of bentonite and charcoal, two yeast cell wall products, and a plant fiber-based novel filter additive. The results of this study show that all the agents tested reduced both residues and volatile compounds in wine, with activated charcoal having the strongest effect and bentonite the weakest. The mixed agents and yeast wall products showed less aroma losses than charcoal products, but also lower residue reduction. Plant fibers showed good reduction of pesticides with moderate aroma damage, but these results need to be confirmed under practical conditions.

Riboflavin removal by commercial bentonites and charcoals in white and red wine

Riboflavin (RF) represents one of the primary molecules undergoing photo-degradation in wine and its excited form act as intermediate in light-induced oxidation reactions responsible for the light-struck fault. A recent study revealed bentonites (BENs) and charcoals (CHAs) as the most promising fining agents for riboflavin removal in model wine. This work explored their potential on both white and red wine. Eleven BENs and eleven CHAs were compared. BENs exhibited a limited capacity, while decolouring carbons confirmed a great attitude to RF removal in white wine even at low dosages. Nevertheless, CHAs efficiency shows a sensible reduction in red wine.

Effect of Pre-Fermentative Maceration and Fining Agents on Protein Stability, Macromolecular, and Phenolic Composition of Albariño White Wines: Comparative Efficiency of Chitosan, k-Carrageenan and Bentonite as Heat Stabilisers

In this work, the effect of pre-fermentative skin maceration (PFSM) on the chemical composition of the macromolecular fraction, polysaccharides and proteins, phenolic compounds, chromatic characteristics, and protein stability of Albariño monovarietal white wines was studied. PFSM increased the extraction of phenolic compounds and polysaccharides and reduced the extraction of pathogenesis-related proteins (PRPs). PFSM wine showed significantly higher protein instability. Sodium and calcium bentonites were used for protein stabilisation of wines obtained with PFSM (+PFSM) and without PFSM (−PFSM), and their efficiencies compared to fungal chitosan (FCH) and k-carrageenan. k-Carrageenan reduced the content of PRPs and the protein instability in both wines, and it was more efficient than sodium and calcium bentonites. FCH was unable to heat stabilise both wines, and PRPs levels remained unaltered. On the other hand, FCH decreased the levels of wine polysaccharides by 60%. Sodium and calcium bentonite also decreased the levels of wine polysaccharides although to a lower extent (16% to 59%). k-Carrageenan did not affect the wine polysaccharide levels. Overall, k-carrageenan is suitable for white wine protein stabilisation, having a more desirable impact on the wine macromolecular fraction than the other fining agents, reducing the levels of the wine PRPs without impacting polysaccharide composition.

Wine Stabilisation: An Overview of Defects and Treatments

Wine is widely consumed due to its distinctive sensory characteristics. However, during wine production and storage, several defects can appear. These can be the result of unwanted microbiological activity or due to the unbalanced levels of some compounds resulting from an unbalanced grape chemical composition or inadequate winemaking practices and storage conditions. The main purpose of wine stabilisation is the removal of wine defects, either visual, olfactive, gustative, or tactile, the increase in wine safety and stability by fining and filtration operations, avoiding the occurrence of some usual wine precipitations after bottling. Although the best strategy is to prevent the appearance of wine defects, when present, several fining agents or additives, and technologies are available today with different performances and impact on wine quality. By physicochemical and sensory analysis, the defect is detected, and if the objective is removing them, some laboratory trials are performed to achieve a better treatment approach. This review overviews the principal wine defects and treatments available today and in the near future. Generally, the future trend is the use of more sustainable and environmentally friendly fining agents and technologies, looking for treatments with better performance and specificity.

Sustainable Replacement Strategies for Bentonite in Wine Using Alternative Protein Fining Agents

Protein stability is an important quality attribute in wines and protein haze will lead to consumer rejection. Traditionally, stability is achieved by bentonite addition; however, environmental concerns and disposal problems mean that alternatives are required to achieve the same goal. In this study, the use of Sacharomyces paradoxus, chitosan, polystyrene, carboxymethyl cellulose, and bentonite were evaluated. Trials in finished wines were agitated for 10 h overnight and analyzed for turbidity and color characteristics spectrophotometrically. Experiments were conducted with wines that are expected to develop protein instabilities, Muscat Canelli, White Zinfandel, Cabernet Sauvignon blanc de noir, Barbera rosé, and Touriga Nacional. Results indicate that S. paradoxus can help with the removal of proteins from wine. Wines with low protein instability can be stabilized with S. paradoxus as well as polystyrene and chitosan to a lesser degree. All fining agents except for bentonite show efficiency variability between white and red wines. With an average protein reduction around 50%, none of the alternative fining methods could reach the efficiency level of bentonite. Experiments in a model system confirm the findings and explain some of the mechanisms involved, for example the specificity of chitosan and challenges related to the use of yeast as a fining agent.

Wine Polyphenol Content and Its Influence on Wine Quality and Properties: A Review

Wine is one of the most consumed beverages around the world. It is composed of alcohols, sugars, acids, minerals, proteins and other compounds, such as organic acids and volatile and phenolic compounds (also called polyphenols). Polyphenols have been shown to be highly related to both (i) wine quality (color, flavor, and taste) and (ii) health-promoting properties (antioxidant and cardioprotective among others). Polyphenols can be grouped into two big families: (i) Flavonoids, including anthocyanidins, flavonols, flavanols, hydrolysable and condensed tannins, flavanones, flavones and chalcones; and (ii) Non-flavonoids, including hydroxycinnamic acids, hydroxybenzoic acids, stilbenes, tyrosol and hydroxytyrosol. Each group affects in some way the different properties of wine to a greater or a lesser extent. For that reason, the phenolic composition can be managed to obtain singular wines with specific, desirable characteristics. The current review presents a summary of the ways in which the phenolic composition of wine can be modulated, including (a) invariable factors such as variety, field management or climatic conditions; (b) pre-fermentative strategies such as maceration, thermovinification and pulsed electric field; (c) fermentative strategies such as the use of different yeasts and bacteria; and (d) post-fermentative strategies such as maceration, fining agents and aging. Finally, the different extraction methods and analytical techniques used for polyphenol detection and quantification have been also reviewed.