Efficiency of carboxymethylcellulose in red wine tartaric stability: Effect on wine phenolic composition, chromatic characteristics and colouring matter stability

Influence of Protective Colloids on Calcium Tartrate Stability and the Astringency Perception in a Red Wine

Calcium tartrate instability in wines has been a neglected topic for many years. However, it seems that this problem is gaining prominence, and the industry welcomes inputs to address this issue. Among the alternatives that winemakers use for tartrate salt stabilization, the addition of authorized protective colloids is one of the best choices because they are easy to apply and have a low energetic cost. In the present study, the same red wine was treated with five different commercially available protective colloids in triplicate. The effectiveness of such colloids on calcium tartrate potential instability was estimated, in addition to their side effects on the phenolic composition of the treated wines and their astringency perception, as assessed by sensory analyses of the treated wine. The results show that, under these trial conditions, carboxymethylcellulose is the best choice for reducing the risk of calcium tartrate precipitation in wine. Moreover, the application of protective colloids to the wines had little effect on their color, phenolic composition, or evolution during one year of bottle storage. Finally, the addition of protective colloids did not impact the astringency intensity, but it influenced the dynamic perception of astringency according to the temporal dominance of sensation analysis.

Wine Volatilome as Affected by Tartaric Stabilization Treatments: Cold Stabilization, Carboxymethylcellulose and Metatartaric Acid

The primary cause of bottled wine sediment is tartrate crystal precipitation. To prevent this, wines undergo a stabilization process before bottling. The most commonly used method is cold stabilization, which induces the precipitation of tartrate crystals that are then removed, thereby eliminating the excess ions that cause instability in wine. Another approach to tartaric stabilization is using enological stabilizers with a colloid protective effect, which prevents the formation of tartrate crystals. The most commonly used tartaric stabilizers are sodium carboxymethylcellulose (CMC) and metatartaric acid. However, both have drawbacks: they are semi-synthetic products, and metatartaric acid degrades over time, losing its stabilizing effect. This study aims to compare the effects of cold stabilization, stabilization with CMC, and metatartaric acid on the chemical composition, particularly the volatilome, of white, rosé, and red wines. Cold stabilization significantly impacted the wine volatilome, especially in white and rosé wines, by decreasing total alcohols and increasing total esters. It also reduced the color intensity of rosé and red wines by lowering monomeric anthocyanins. In contrast, enological stabilizers had minimal impact on the wines' phenolic composition, chromatic characteristics, and volatilome. The sensory impact of cold stabilization is complex; it can potentially enhance the aroma of white and rosé wines by increasing ester VOCs and decreasing higher alcohols, but it negatively affects the color of rosé and red wines.

Gradient Hierarchically Porous Ionic-Junction Fibers of Wet-Spun Carboxymethyl Cellulose Coagulated with Copper Sulfate

Polyelectrolyte-based ionic-junction fibers newly serve as signal transmission and translation media between electronic devices and biological systems, facilitating ion transport within organic matrices. In this work, we fabricated gel filaments of carboxymethyl cellulose (CMC) chelated with Cu(II) ions through wet-spinning, using a saturated coagulant of CuSO4. Interestingly, the as-spun fibers exhibited dramatic 3D porous frameworks that varied with the temperature and precursor concentration. At 20 °C, the Cu(II) chelation networks favored the formation of well-organized cellular chambers or corrugated channels, displaying dense stacking patterns. However, critical transitions from cellular chambers to corrugated channels occurred at precursor dope concentrations of approximately 2 and 7 wt %, with the porous structure diminishing beyond 8 wt %. We have proposed schematic diagrams to mimic the 3D pore structure, dense porous stacking, and formation mechanism, according to electronic micrographs. Our investigations revealed that the distinct ion-junction channels or chambers are under the control of axial drawing extension as well as the outside-inside penetration of Cu(II) ions into the dope and inside-outside diffusion of water into coagulants. Therefore, controlling the metal chelation-water diffusion process at specific temperatures and concentrations will offer valuable insights for tailoring ionic-junction soft filaments with gradient hierarchically porous structures and shape memory properties.

Use of potassium polyaspartate on white wines: interaction with proteins and aroma compounds

The precipitation of tartaric salts represents one of the main visual sensory faults of white wines. It can be prevented by cold stabilization or adding some adjuvants, such as potassium polyaspartate (KPA). KPA is a biopolymer that can limit the precipitation of tartaric salts linking the potassium cation, however, it could interact also with other compounds affecting wine quality. The present work aims to study the effect of potassium polyaspartate on proteins and aroma compounds of two white wines, at different storage temperatures (4 °C and 16 °C). The KPA addition showed positive effects on the quality of wines, with a significant decrease of unstable proteins (up to 92%), also related to better wine protein stability indices. A Logistic function well described the effect of KPA and storage temperature on protein concentration (R² > 0.93; NRMSD: 1.54-3.82%). Moreover, the KPA addition allowed the preservation of the aroma concentration and no adversely effects were pointed out. Alternatively to common enological adjuvants, KPA could be considered a multifunctional product against tartaric and protein instability of white wines, avoiding adverse effects on their aroma profile.

Comparison of the Electrodialysis Performance in Tartrate Stabilization of a Red Wine Using Aliphatic and Aromatic Commercial and Modified Ion-Exchange Membranes

The application of electrodialysis for tartrate stabilization and reagent-free acidity correction of wine and juices is attracting increasing interest. New aliphatic membranes CJMC-3 and CJMA-3 and aromatic membranes CSE and ASE were tested to determine their suitability for use in these electrodialysis processes and to evaluate the fouling of these membranes by wine components for a short (6-8 h) operating time. Using IR spectroscopy, optical indication and measurement of surface contact angles, the chemical composition of the studied membranes, as well as some details about their fouling by wine components, was clarified. The current-voltage charsacteristics, conductivity and water-splitting capacity of the membranes before and after electrodialysis were analyzed. We found that in the case of cation-exchange membranes, complexes of anthocyanins with metal ions penetrate into the bulk (CJMC-3) or are localized on the surface (CSE), depending on the degree of crosslinking of the polymer matrix. Adsorption of wine components by the surface of anion-exchange membranes CJMA-3 and ASE causes an increase in water splitting. Despite fouling under identical conditions of electrodialysis, membrane pair CJMC-3 and CJMA-3 provided 18 ± 1 tartrate recovery with 31 · 10^-3 energy consumption, whereas CSE and ASE provided 20 ± 1% tartrate recovery with an energy consumption of 28 · 10^-3 Wh, in addition to reducing the conductivity of wine by 20 ± 1%. The casting of aliphatic polyelectrolyte films on the surface of aromatic membranes reduces fouling with a relatively small increase in energy consumption and approximately the same degree of tartrate recovery compared to pristine CSE and ASE.

Isolation, Characterization, and Compositional Analysis of Polysaccharides from Pinot Noir Wines: An Exploratory Study

It has been reported that polysaccharides in wine can interact with tannins and other wine components and modify the sensory properties of the wine. Unfortunately, the contribution of polysaccharides to wine quality is poorly understood, mainly due to their complicated structure and varied composition. In addition, the composition and molecular structure of polysaccharides in different wines can vary greatly. In this study, the polysaccharides were isolated from pinot noir wine, then separated into high-molecular-weight (PNWP-H) and low-molecular-weight (PNWP-L) fractions using membrane-based ultrafiltration. Each polysaccharide fraction was further studied using size exclusion chromatography, UV-Vis, FT-IR, matrix-assisted laser desorption/ionization-high-resolution mass spectrometry, and gas chromatography-mass spectrometry (GC-MS). The results showed that PNWP-L and PNWP-H had different chemical properties and compositions. The FT-IR analysis showed that PNWPs were acidic polysaccharides with α- and β-type glycosidic linkages. PNWP-L and PNWP-H had different α- and β-type glycosidic linkage structures. FT-IR showed stronger antisymmetric and symmetric stretching vibrations of carboxylate anions of uronic acids in PNWP-L, suggesting more uronic acid in PNWP-L. The size exclusion chromatography results showed that over 72% of the PNWP-H fraction had molecular sizes from 25 kDa to 670 kDa. Only a small percentage of smaller molecular polysaccharides was found in the PNWP-H fraction. In comparison, all of the polysaccharides in the PNWP-L fraction were below 25 KDa, with a majority distributed approximately 6 kDa (95.1%). GC-MS sugar composition analysis showed that PNWP-L was mainly composed of galacturonic acid, rhamnose, galactose, and arabinose, while PNWP-H was mainly composed of mannose, arabinose, and galactose. The molecular size distribution and sugar composition analysis suggested that the PNWP-L primarily consisted of rhamnogalacturonans and polysaccharides rich in arabinose and galactose (PRAG). In comparison, PNWP-H were mostly mannoproteins and polysaccharides rich in arabinose and galactose (PRAG). Further research is needed to understand the impacts of these fractions on wine organoleptic properties.

Development of a new paper-based voltage step electrocoagulation technique and application to wine classification

This study developed a novel voltage step electrocoagulation (VSEC) technique on paper for analysis and classification of red wine samples. The concept relies on the electrode system applying voltage steps along a strip of filter paper soaked with a wine sample. The system employed a cathode array system (CAS) for voltage step application and an aluminium anode undergoing corrosion to form the green sludges responsible for wine color bleaching along the paper. The VSEC technique led to the shade of colors along the paper which can be observed by the naked-eye or using image processing software. The system was applied to classify 15 wine samples into different groups and to perform dilution and adulteration tests. In addition, the approach could be applied to approximate antioxidant properties of the wine samples as observed via the correlation between the results from VSEC and IC₅₀ values obtained from the DPPH assay with an R² of 0.76.

Effect of Cold Stabilization Duration on Organic Acids and Aroma Compounds during Vitis vinifera L. cv. Riesling Wine Bottle Storage

During the storage of wines in bottles, especially white wines, tartrate crystallization often occurs, which reduces the commercial value of the wines and therefore needs to be avoided by performing cold stabilization treatments before bottling. However, whether different cold treatment durations impact the quality of a wine’s aroma has not yet been of special concern. This research was conducted at an industrial scale to explore how cold treatments at −5.3 °C for 10 to 15 days impact the organic acids, aroma compounds, and sensory quality of Riesling dry white wines, and the variation was documented at the end of treatment, and at 6 and 12 months of bottle storage. The results showed that cold treatments significantly reduced tartaric acid concentrations and significantly affected the concentrations of most aroma components in the wines only after 12 months of bottle storage, including the main components of esters, norisoprenoids, terpenoids, and furfural. Moreover, the concentrations of some components showed an increasing trend with the bottle storage, especially 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN), the characteristic volatile of Riesling wine, suggesting that an acidic condition resulting from cold treatment might facilitate the conversion of some aroma precursors into volatiles. In conclusion, cold stabilization treatments, within limits, can improve tartaric acid stability and could promote the conservation of aroma compounds during bottle storage without adversely affecting the aroma profile of the wines.

The influence of agricultural practices in vineyards on the predisposition of wines to crystalline turbidities

On the example of the Cabernet-Sauvignon variety, the dependence of the physicochemical parameters of grape must and the wine materials produced from it, on the formation of the grape bush (Cordon or Guyot) and green operations (chasing the upper leaves, pinching, removing stepsons) is shown. The influence of the listed factors on the predisposition of wines to crystalline turbidities is shown.