Effect of SO2, reduced glutathione and ellagitannins on the shelf life of bottled white wines

Towards Sulphite-Free Winemaking: A New Horizon of Vinification and Maturation

The complex dynamics between oxygen exposure, sulphur dioxide (SO2) utilization, and wine quality are of the utmost importance in wine sector, and this study aims to explore their fine balance in winemaking. As a common additive, SO2 works as an antiseptic and antioxidant. However, its excessive use has raised health concerns. Regulatory guidelines, including Council Regulation (EC) N° 1493/1999 and Commission Regulation (EC) No 1622/2000, dictate SO2 concentrations in wines. The increasing demand for natural preservatives is driving the search for alternatives, with natural plant extracts, rich in phenolic compounds, emerging as promising substitutes. In this context, Bioma Company has proposed alternative additives deriving from vineyard waste to replace SO2 during winemaking. Thus, the aim of the present work was to compare the compositional characteristics between the product obtained with the alternative vinification and the traditional one during the winemaking, as well as the aroma compositions of the final wines. After a year of experimentation, the wines produced with Bioma products showed compositional characteristics comparable to their traditional counterparts. Notably, these wines comply with current legislation, with significantly reduced total sulphur content, allowing their designation as "without added sulphites". Bioma products emerge as potential catalysts for sustainable and health-conscious winemaking practices, reshaping the landscape of the industry.

A Review on Wine Flavour Profiles Altered by Bottle Aging

The wine flavour profile directly determines the overall quality of wine and changes significantly during bottle aging. Understanding the mechanism of flavour evolution during wine bottle aging is important for controlling wine quality through cellar management. This literature review summarises the changes in volatile compounds and non-volatile compounds that occur during wine bottle aging, discusses chemical reaction mechanisms, and outlines the factors that may affect this evolution. This review aims to provide a deeper understanding of bottle aging management and to identify the current literature gaps for future research.

Sulfur dioxide-free Verdejo wines through the use of a pure stilbene extract: exploring possible synergistic effect with glutathione

BACKGROUND

The search for alternatives to sulfur dioxide (SO₂ ) in white wine production is a tough challenge for the oenological industry. The current article investigates the effectiveness of several preservatives in protecting Verdejo white wines. The following wines were elaborated: without preservative (CT wines), with SO₂ (SO₂ wines), with stilbene-enriched extract (ST99 wines), with glutathione (GSH wines) and finally with the combination stilbene extract plus glutathione (ST99-GSH wines).

RESULTS

ST99 extract preserved the wines from malolactic fermentation (MLF), maintained the quality parameters of the wines, but affected their color from the beginning of the process. Synergistic effects between ST99 and GSH were found for oxygen consumption rates, related to oxidation processes. The content of amino acids and biogenic amines was slightly affected by the treatments, but the quality or safety of the wines was not compromised. However, after 12 months of ageing in bottle, the SO₂ wines showed the highest score in the sensory analysis. The reasons for the evolution of treated wines and the implications of this study for maintaining the quality of free SO₂ white wines are discussed.

CONCLUSION

ST99 may be proposed as an alternative to SO₂ in wines to be consumed in the short term. Its combination with GSH does not prolong its shelf-life. © 2022 Society of Chemical Industry.

Impact of tannin addition on the antioxidant activity and sensory character of Malagousia white wine

Enological tannins are assessed as promising alternative to SO2 in order to control oxidative process during winemaking, due to allergic reactions incurred by sulfite sensitive individuals. In the present study, the commercial enological Tara tannin "Vitanil B″ was added, as alternative to the addition of sulfites, at different concentrations (100-500 mg/L) in white wine from grapes of Vitis vinifera L. var. Malagousia in order to enhance antioxidant stability and sensory character of the wine. Considering photometric analyses and chromatic parameters results, tannin addition (300 mg/L) in Malagousia enhanced total phenolic content, antioxidant and antiradical activity and prevented color deterioration, for a storage period of 100 d, compared to control and sulfited wines. Moreover, aroma quality, body, after taste and overall acceptance of wine treated with 300 mg/L tannin, were highly appreciated and received the highest scores. The overall evaluation of tannin addition was performed by Principal Component Analysis, leading to discrimination of wines, according to photometric, color and sensory analysis parameters. Conclusively, tannin addition resulted in a considerable increase of total phenolic content, antioxidant and antiradical activity, compared to the control and sulfited wines, maintaining the sensory parameters and overall acceptance of Malagousia wine.

Wine Storage at Cellar vs. Room Conditions: Changes in the Aroma Composition of Riesling Wine

Storage temperature is one of the most important factors affecting wine aging. Along with bottling parameters (type of stopper, SO₂ level and dissolved O₂ in wine), they determine how fast wine will evolve, reach its optimum and decline in sensory quality. At the same time, lowering of the SO₂ level in wine has been a hot topic in recent years. In the current work, we investigated how Riesling wine evolved on the molecular level in warm (~25 °C) and cool (~15 °C) conditions depending on the SO₂ level in the wine (low, medium and high), flushing of the bottle's headspace with CO₂ and three types of stoppers (Diam 30, Diam 30 origin and Diam 5) with different OIR levels (0.8-1.3 mg) and OTR levels (0.3-0.4 mg/year). It was demonstrated that the evolution of primary and secondary aromas, wine color and low molecular weight sulfur compounds (LMWSCs) during the two years of aging mainly depended on the storage temperature. Variation in the SO₂ level and CO₂ in the headspace affected mostly certain LMWSCs (H₂S, MeSH) and β-damascenone. New aspects of C₁₃-norisprenoids and monoterpenoids behavior in Riesling wine with different levels of SO₂ and O₂ were discussed. All three types of stoppers showed very close wine preservation properties during the two years of storage. The sensory analysis revealed that, after only six months, the warm stored wines with a low SO₂ level were more oxidized and different from the samples with medium and high SO₂ levels. A similar tendency was also observed for the cool stored samples.

Combined effects of sulfur dioxide, glutathione and light exposure on the conservation of bottled Sauvignon blanc

Oxygen exposure may trigger a series of changes that could be detrimental to the quality white wines. This study evaluated the combined effects of sulfur dioxide, glutathione and light exposure on the chemistry and sensory perception of bottled Sauvignon blanc. The wines were manually bottled into clear bottles, closed with low oxygen transfer rate stoppers, and stored for three months, either exposed or protected from light. The wines exposed to artificial light showed higher rates of sulfite loss and oxygen consumption, were significantly darker in color, exhibited significant changes in the concentration of phenolics and volatile compounds, were perceived as less fruity/floral, and had higher nuances of solvent, earthy and honey aromas than the ones protected from light. The treatments with higher amounts of initial sulfites and glutathione were able to delay some of these changes but were less significant than protecting the wines from artificial light.

Bottle Aging and Storage of Wines: A Review

Wine is perhaps the most ancient and popular alcoholic beverage worldwide. Winemaking practices involve careful vineyard management alongside controlled alcoholic fermentation and potential aging of the wine in barrels. Afterwards, the wine is placed in bottles and stored or distributed in retail. Yet, it is considered that wine achieves its optimum properties after a certain storage time in the bottle. The main outcome of bottle storage is a decrease of astringency and bitterness, improvement of aroma and a lighter and more stable color. This is due to a series of complex chemical changes of its components revolving around the minimized and controlled passage of oxygen into the bottle. For this matter, antioxidants like sulfur oxide are added to avoid excessive oxidation and consequent degradation of the wine. In the same sense, bottles must be closed with appropriate stoppers and stored in adequate, stable conditions, as the wine may develop unappealing color, aromas and flavors otherwise. In this review, features of bottle aging, relevance of stoppers, involved chemical reactions and storage conditions affecting wine quality will be addressed.

Phenolic and Aroma Changes of Red and White Wines during Aging Induced by High Hydrostatic Pressure

The aim of this study was to investigate use of high hydrostatic pressure (HHP) along with different antioxidants (glutathione and SO2) as an alternative method for wine preservation and production of low-SO2 wines. In the first phase of the study, low-SO2, young red and white wines were pressurized at three pressure levels (200, 400 and 600 MPa) for 5, 15 and 25 min at room temperature, and analyzed immediately after treatments. Additionally, for the wine aging experiment, red and white wines with standard-SO2, low-SO2+glutathione and low-SO2 content were treated with HHP treatment (200 MPa/5 min) and stored for 12 months in bottles. Color parameters, phenolic and aroma compounds were determined. The sensory evaluation was also conducted. HHP showed very slight, but statistically significant changes in the chemical composition of both red and white wine right after the treatment, and the main variations observed were related to the different pressures applied. Furthermore, during aging, most of the differences observed in chemical composition of pressurized wines, both red and white, were statistically significant, and greater in wines with a lower content of antioxidants. However, after 12 months of aging, some differences between unpressurized and pressurized samples with standard SO2 content were lost, primarily in aroma compounds for red wine and in color and phenolics for white wine. Additionally, similar values were obtained for mentioned characteristics of red and white wines in pressurized samples with standard SO2 and low SO2+glutathione, indicating that HHP in combination with glutathione and lower doses of SO2 might potentially preserve wine. The sensory analysis confirmed less pronounced changes in the sensory attributes of pressurized wines with higher concentration of antioxidants. Furthermore, the treatments applied had a slightly higher effect on the sensory properties of white wine.

Effect of Different Reducing Agents on Aromatic Compounds, Antioxidant and Chromatic Properties of Sauvignon Blanc Wine

Sulfur dioxide (SO2) is widely the most used enological additive with reductive, antiseptic and dissolving properties. According to increasing health concerns and the gradual decrease in total SO2 concentrations allowed in wine, alternative and supplementary agents for preservation are being investigated. For this reason, the current study was focused on the impact of different commercial reductive agents on white wine antioxidant activity and chemical composition. The effect of additives that combine sulfites, ascorbic acid and enological tannins were compared against standard 5% sulfurous acid (H2SO3) during the pre-fermentative treatments of Sauvignon Blanc must (Vitis vinifera L.). The basic parameters of quality, free amino-nitrogen and total polyphenoliccompounds in must were analyzed. Gas chromatography and spectrophotometric methods were used to investigate the overall volatile composition, antioxidant and chromatic parameters in wines. The obtained results undoubtedly pointed out the positive effect of sulfuric acid on the fermentation dynamics. Furthermore, application of combined reducing additives with potassium metabisulfite, L-ascorbic acid, gallotannins and ellagitannins, resulted in a higher antioxidant capacity and increased concentration of aromatic compounds and their odor activity values in Sauvignon Blanc wine.

Use of potassium polyaspartate for stabilization of potassium bitartrate in wines: influence on colloidal stability and interactions with other additives and enological practices

The research was aimed at verifying the efficacy of potassium polyaspartate (KPA), added at bottling, for prevention of the precipitation of potassium bitartrate (KHT). The stability of KHT was determined with the mini-contact test and the cold test. The effect of KPA on the colloidal stability of white and red wines was also studied. Turbidity, color, and total anthocyanins and flavonoids (red wines only) were monitored. In the first experiment, the stabilizing effect of KPA added at bottling, with or without Arabic gum, tannins, and filtration (0.45 µm cut-off), was studied in comparison with metatartaric acid (MTA). KPA proved to have good stabilizing efficacy for prevention of KHT precipitation and maintained its effect in all trials after 1 year of bottle aging. On the contrary, all the trials with MTA became unstable after 6 months. Moreover, KPA did not modify wine turbidity and color. The filtration (0.45 µm cut-off) did not reduce its stabilizing efficacy. In the second experiment, the effect of KPA added to a white and a red wine, respectively clarified with casein and gelatin or vegetal protein and/or bentonite, was studied. KPA did not cause any increase in turbidity or appreciable changes in the color of the white wines of the different trials. A preliminary treatment with bentonite can prevent the possible formation of haze in red wines after the addition of KPA. PRACTICAL APPLICATION: KPA prevented the precipitation of KHT in unstable white and red wines. The stabilizing effect persisted after 1 year of bottle aging. The oenologist does not need to adopt special prescriptions when using KPA in combination with Arabic gum or tannins in prebottling operations. A treatment with bentonite prevented the appearance of turbidity in red wines after the addition of KPA.

Analysis of factors related to browning of Dangshan pear (Pyrus spp.) wine

The effects of different dissolved oxygen concentrations (DOC) on the browning degree, amino acids, total phenols, reducing sugars, polyphenoloxidase (PPO), peroxidase (POD), phenylalanine ammonia-lyase (PAL) of pear wine, and the relationship between various quality indicators and browning degree were investigated. Dynamic model fitting analysis of the changes of physiochemical indicators of pear wine in the storage process were performed. The importance of the physiochemical indicators effect on the browning of pear wine during the storage process was analyzed by OPLS (orthogonal partial least squares discriminant analysis), and the effect of dissolved oxygen on the browning of pear wine was systematically revealed. The results showed that dissolved oxygen, total phenols and amino acids had the greatest influence on the browning degree of pear wine. It provided a theoretical basis for revealing the browning mechanism and inhibiting the browning of pear wine.

Relationship between polyphenolic content, antioxidant properties and oxygen consumption rate of different tannins in a model wine solution

The polyphenolic content and the antioxidant capacity of seven tannins with different botanical origin were measured with spectrophotometric methods (Folin-Ciocalteu, Total Polyphenols Index, DPPH, FRAP), HPLC (phloroglucinolysis), voltammetric analysis (Linear Sweep Voltammetry, LSV). The oxygen consumption rate (OCR) was measured in an oxygen saturated model wine solution, containing transition metals and metabisulphite, with a noninvasive luminescence-based technology. The results showed a high variability in polyphenolic concentration related to the botanical origin of tannins. The OCR determined over 21 days was described by quadratic equations, with coefficients varying with tannin botanical origin, dose and SO₂ concentration. The tannins ranked differently for antioxidant capacity, depending on the kind of test. The oxygen consumption parameters were positively correlated only with the LSV data measured with anodic current between 100 and 1200 mV (LSV_1200mV) and with the FRAP index.

Oxygen and SO2 Consumption Rates in White and Rosé Wines: Relationship with and Effects on Wine Chemical Composition

This Article addresses the study of O₂ and SO₂ consumption rates of white and rosé wines, their relationship to the initial chemical composition, and their effects on the chemical changes experienced by wine during oxidation. Eight wines were subjected to five consecutive air-saturation cycles. O₂ was monitored periodically; SO₂, color, and antioxidant indexes were determined after each cycle, and the initial and final compositions of the wines were thoroughly determined. Wines consumed oxygen at progressively decreasing rates. In the last cycles, after a strong decrease, consistent increases of oxygen levels were seen. Oxygen consumption rates were satisfactorily modeled, being proportional to wine copper, quercetin, and kaempherol contents and negatively proportional to cinnamic acids. SO₂ consumption rates were highly diverse between wines and were positively related to free SO₂, Mn, and pH, among others. In the last saturations, SO₂ consumption took place regardless of O₂ consumption, implying that SO₂ should reduce chemical species oxidized in previous saturations. Some volatile phenols seem to be the end point of radical-mediated oxidation of polyphenols taking place preferably in the first saturation.

Evaluation of the use of sulfur dioxide and glutathione to prevent oxidative degradation of malvidin-3-monoglucoside by hydrogen peroxide in the model solution and real wine

In this study the oxidative degradation by hydrogen peroxide of native grape anthocyanin was studied in model solutions and in red wines added with increasing concentration of sulfur dioxide and glutathione (GSH). The presence of hydrogen peroxide and metal ions in traces allowed to investigate the possibility to use GSH to prevent Fenton reaction in wine conditions. Two different pH of wine were considered: 3.20 and 3.80. The protective effect of sulfur dioxide on malvidin 3-monoglucoside degradation was higher at lower pH in model solution. No effect of pH on sulfur dioxide action towards the native anthocyanin in real wine was detected. Surprisingly GSH determined an increase in the degradation of malvidin 3-monoglucoside regardless of pH. Therefore, GSH is not effective in prevent native anthocyanins loss due to the Fenton reaction during red wine aging.