Influence of Storage Conditions on the Composition of Red Wines

Evolution in the Bottling of Cabernet Sauvignon Wines Macerated with Their Own Toasted Vine-Shoots

This work studies, for the first time, the effect of the use of Cabernet Sauvignon vine-shoots as an enological additive (called "Shoot Enological Granule", SEG) in wines of the same variety. SEGs were added in two doses (12 and 24 g/L) at the end of malolactic fermentation, and after that, wines were bottled for six months. The phenolic and volatile composition and sensory profiles of wines were analyzed at bottling and after six months. The results showed a decrease in the total content of phenolic compounds with bottle time; however, stilbenes─specifically trans-resveratrol─were maintained at significant levels in SEG wines. In contrast, the total content of volatile compounds, mainly esters, increased with bottle aging. Finally, in terms of sensory profile, SEG wines showed a clear differentiation between the descriptors and the control, with more-integrated aromas after bottle time with more toasted, nutty vanilla notes, as well as silkier and less bitter tannins, compared to the control.

Chemical Stability of Thiol and Flavanol Sulfonation Products during Wine Aging Conditions

Bisulfite (HSO3-) is the predominant form of sulfur dioxide, present as free and bound to wine relevant electrophiles under wine acidic pH. While sulfonation reactions of flavanols and thiols have been recently reported as key for wine preservation against oxidation, the transient mechanisms and physicochemical parameters responsible for that remain unknown. In the present study, sulfonation reaction kinetics of thiols and flavanols were monitored under simulated wine aging conditions. The reaction products were then characterized by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, and their chemical stability during time was determined by 1H NMR spectroscopy. Thiol and flavanol sulfonation reaction yields were both promoted by the presence of iron and oxygen, while their chemical stability was confirmed under the same conditions. The sulfonation derivatives of epicatechin and cysteine were synthesized and quantified in young and aged wines. Higher concentrations were reported for both metabolites in older wines, indicating their participation on the strongly bound sulfur dioxide fraction. These findings offer new prospects for more precise use of sulfur dioxide in winemaking.

Novel insight into the role of sulfur dioxide in fruits and vegetables: Chemical interactions, biological activity, metabolism, applications, and safety

Sulfur dioxide (SO₂) are a category of chemical compounds widely used as additives in food industry. So far, the use of SO₂ in fruit and vegetable industry has been indispensable although its safety concerns have been controversial. This article comprehensively reviews the chemical interactions of SO₂ with the components of fruit and vegetable products, elaborates its mechanism of antimicrobial, anti-browning, and antioxidation, discusses its roles in regulation of sulfur metabolism, reactive oxygen species (ROS)/redox, resistance induction, and quality maintenance in fruits and vegetables, summarizes the application technology of SO₂ and its safety in human (absorption, metabolism, toxicity, regulation), and emphasizes the intrinsic metabolism of SO₂ and its consequences for the postharvest physiology and safety of fresh fruits and vegetables. In order to fully understand the benefits and risks of SO₂, more research is needed to evaluate the molecular mechanisms of SO₂ metabolism in the cells and tissues of fruits and vegetables, and to uncover the interaction mechanisms between SO₂ and the components of fruits and vegetables as well as the efficacy and safety of bound SO₂. This review has important guiding significance for adjusting an applicable definition of maximum residue limit of SO₂ in food.

Application progress of intelligent flavor sensing system in the production process of fermented foods based on the flavor properties

Fermented foods are sensitive to the production conditions because of microbial and enzymatic activities, which requires intelligent flavor sensing system (IFSS) to monitor and optimize the production process based on the flavor properties. As the simulation system of human olfaction and gustation, IFSS has been widely used in the field of food with the characteristics of nondestructive, pollution-free, and real-time detection. This paper reviews the application of IFSS in the control of fermentation, ripening, and shelf life, and the potential in the identification of quality differences and flavor-producing microbes in fermented foods. The survey found that electronic nose (tongue) is suitable to monitor fermentation process and identify food authenticity in real time based on the changes of flavor profile. Gas chromatography-ion mobility spectrometry and nuclear magnetic resonance technology can be used to analyze the flavor metabolism of fermented foods at various production stages and explore the correlation between flavor substances and microorganisms.

Characterisation of Extracts Obtained from Unripe Grapes and Evaluation of Their Potential Protective Effects against Oxidation of Wine Colour in Comparison with Different Oenological Products

Unripe grapes (UGs) are a waste product of vine cultivation rich in natural antioxidants. These antioxidants could be used in winemaking as alternatives to SO2. Three extracts were obtained by maceration from Viognier, Merlot and Sangiovese UGs. The composition and antioxidant activity of the UG extracts were studied in model solutions at different pH levels. The capacity of the UG extracts to protect wine colour was evaluated in accelerated oxidation tests and small-scale trials on both red and white wines during ageing in comparison with sulphur dioxide, ascorbic acid and commercial tannins. The Viognier and Merlot extracts were rich in phenolic acids while the Sangiovese extract was rich in flavonoids. The antioxidant activity of the extracts and commercial tannins was influenced by the pH. In the oxidation tests, the extracts and commercial products showed different wine colour protection capacities in function of the type of wine. During ageing, the white wine with the added Viognier UG extract showed the lowest level of colour oxidation. The colour of the red wine with the UG extract evolved similarly to wine with SO2 and commercial tannins. The obtained results indicated that natural and healthy UG extracts could be an interesting substitute for SO2 during wine ageing.

Use of Untargeted Liquid Chromatography-Mass Spectrometry Metabolome To Discriminate Italian Monovarietal Red Wines, Produced in Their Different Terroirs

The aim of this project was to register, in a liquid chromatography-mass spectrometry-based untargeted single-batch analysis, the metabolome of 11 single-cultivar, single-vintage Italian red wines (Aglianico, Cannonau, Corvina, Montepulciano, Nebbiolo, Nerello, Primitivo, Raboso, Sagrantino, Sangiovese, and Teroldego) from 12 regions across Italy, each one produced in their terroirs under ad hoc legal frameworks to guarantee their quality and origin. The data provided indications regarding the similarity between the cultivars and highlighted a rich list of putative biomarkers of origin wines (pBOWs) characterizing each individual cultivar-terroir combination, where Primitivo, Teroldego, and Nebbiolo had the maximum number of unique pBOWs. The pBOWs included anthocyanins (Teroldego), flavanols (Aglianico, Sangiovese, Nerello, and Nebbiolo), amino acids and N-containing metabolites (Primitivo), hydroxycinnamates (Cannonau), and flavonols (Sangiovese). The raw data generated in this study are publicly available and, therefore, accessible and reusable as a baseline data set for future investigations.

Liquid Chromatography-Mass Spectrometry-Based Metabolomics for Understanding the Compositional Changes Induced by Oxidative or Anoxic Storage of Red Wines

The aim of this work was to study the physicochemical changes of eight red wines stored under conditions differing in O₂ exposure and temperature and time under anoxia. The methods used to analyze the wines included the measurement of volatile sulfur compounds, color, tannin (T) polymerization, and liquid chromatography-mass spectrometry untargeted metabolomic fingerprint. After 3 months, the color of the oxidized samples evolved 4-5 times more intensively than in wines stored under anoxia. The major metabolomic differences between oxidative and anoxic conditions were linked to reactions of acetaldehyde (favored in oxidative) and SO₂ (favored in anoxia). In the presence of oxygen, the C-4 carbocation of flavanols delivered ethyl-linked tannin-anthocyanin (T-A) and tannin-tannin (T-T) adducts, pyranoanthocyanins, and sulfonated indoles, while under reduction, the C-4 carbocation delivered direct linked T-A adducts, rearranged T-T adducts, and sulfonated tannins. Some of these last reactions could be related to the accumulation of reduced species, eventually ending with reductive off-odors.

Wine Aging Technology: Fundamental Role of Wood Barrels

The aging of wines is a process used to preserve wine but also to enhance its properties. It is a process of great interest, mainly because of the additional properties it adds to wines and because of its economic implications. Historically, barrels have been employed for centuries for preserving and aging wine due to their resistance and relative impermeability. In general terms, the wine aging process can be divided into two phases: oxidative and reductive aging. Oxidative aging traditionally takes place in barrels while reductive phase occurs in the bottle. During both processes, oxygen plays a fundamental role as well as other factors, for instance: temperature, light, bottle position, microbial growth or storage time. Likewise, during the aging process, a series of chemical reactions take place influencing the composition and organoleptic profile of wine. At this point, oxidative aging in barrels is a fundamental step. Barrels are directly involved in the produced changes on wine's composition due to the transference of oxygen and phenolic and aromatic compounds from wood to wine. This way, barrels act as an active vessel capable of releasing compounds that affect and improve wine's characteristics. Regarding, the importance of barrels during aging process, some attention must be given to the species most used in cooperage. These species are conventionally oak species, either French or American. However, other non-conventional species are currently being studied as possible wood sources for the production of wines, such as chestnut robinia or other oak species. In the last decades, new approaches have been developed for barrel aging to find new alternatives more suitable, affordable and feasible to sanitize the process, such as other materials different from wood or the use of wood chips, which is regulated since 2006 by the EU. However, even though some of them have shown promising data, barrels are currently the most used technology for the oxidative stage of table wines aging.

Kinetic investigations of sulfite addition to flavanols

Flavanols are an important class of natural products occurring in almost all plants, fruits and vegetables; they have a great influence on wine ageing potential, astringency, colour stability and biological activities. In wine, flavanols react with sulfur dioxide ([Formula: see text]), the most widely used preservative in oenology, leading to sulfonated products. Here we report a kinetic investigation, through LC-MS quantitative measurements carried out at different pH (3 and 4) and temperature values (23, 30, 40, 50 and [Formula: see text]), of the reaction products obtained by [Formula: see text] addition to both monomeric (epicatechin and catechin) and dimeric flavanols (procyanidin B2 and procyanidin B3). The results proved that: (a) the major sulfonation route that leads quickly and in good yields to monomeric 4[Formula: see text]-sulfonated derivatives passes through the acid-catalysed depolymerisation of proanthocyanidins; (b) monomeric flavanols lead to the same 4[Formula: see text]-sulfonated products, although in a considerably slower manner, and also to other sulfonated regioisomers; (c) the kinetic data in our hands, in particular the temperature dependence of the observed rates, suggest the involvement of two completely different reaction mechanisms for the [Formula: see text] addition to dimeric and monomeric flavanol substrates; (d) direct sulfonation of epicatechin is slightly faster than that of catechin.

Effect of Different Yeast Strains and Temperature of Fermentation on Basic Enological Parameters, Polyphenols and Volatile Compounds of Aurore White Wine

The aim of this study was to investigate the content of phenolics by Ultra Performance Liquid Chromatography–Photodiode Array (UPLC–PDA), and volatile compounds by Gas Chromatography–Mass Spectroscopy (GC–MS), antioxidant capacity by 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS^•+) and ferric-reducing antioxidant power (FRAP) assay, and color of Comission Internationale de l’Eclairage system (CIE) L*a*b* cv. Aurora white wine depending on fermentation conditions (a temperature of 12 °C vs. 20 °C and type of natural and commercial yeast (Saccharomyces cerevisiae vs. Saccharomyces bayanus)). The final wine differed in the content of total phenolic compounds (201.0–287.2 mg/L), except for the variants fermented at 20 °C with S. cerevisiae (321.9 and 329.4 mg/L for S. cerevisiae as Challenge Aroma White and SIHA^® Cryaroma type, respectively). A decrease in antioxidant activity ranging from 43.3% to 65.4% (ABTS and FRAP assay) in the matured wine vs. must was demonstrated. S. cerevisiae wine was also characterized by the highest content of total volatile compounds (3.7–4.2 mg/L vs. 1.3 mg/L in the must). In general, the wine obtained with S. cerevisiae had higher alcohol content, antioxidant capacity, and was richer in polyphenolic and volatile compounds.

Rapid Quantitation of 12 Volatile Aldehyde Compounds in Wine by LC-QQQ-MS: A Combined Measure of Free and Hydrogen-Sulfite-Bound Forms

This work outlines a rapid novel methodology for the direct quantitation of 12 volatile aldehyde compounds related to oxidative off-flavors in wine, by measuring the combined free and hydrogen-sulfite-bound forms of each aldehyde compound, consisting of four general aldehydes, four Strecker aldehydes, and four (E)-2-alkenals. The methodology requires minimal preparation of wine samples: the addition of internal standards and 6 g/L sulfur dioxide, and filtration prior to quantitation by liquid chromatography-triple quadrupole-mass spectrometery. Overall, the limit of detection, limit of quantification, accuracy (recovery, 97-114%), and precision (repeatability and reproducibility, RSD ≤ 10%) were satisfactory to enable routine measurement of the 12 aldehyde compounds in wine. The methodology was applied to 20 commercial white and red wines from various varieties and vintages. A general trend of higher concentrations of the aldehyde compounds in white wines compared to red wines was observed.

Condensed Tannin Reacts with SO2 during Wine Aging, Yielding Flavan-3-ol Sulfonates

Numerous monomeric and oligomeric flavanol sulfonation products were observed in 10 wines. Levels of 0.85-20.06 and 0-14.72 mg/L were quantified for two monomeric sulfonated flavan-3-ols and, surprisingly, were generally higher than the well-known native flavan-3-ol monomers. Increasing SO₂ levels during wine aging increased the sulfonate-modified flavan-3-ol monomers and dimers along with higher concentrations of native monomers. The results indicate that >10% of SO₂ is reacting with the C-4 carbocation, formed from acid cleavage of the interflavan bond, perhaps by a bimolecular S_N2-type reaction, and as a reducing agent. In addition, the high SO₂ wine had the lowest protein-binding tannin levels, tannin activity, and mean degree of polymerization (mDP), and acidic SO₂ treatment of condensed tannin abolishes protein binding. Thus, SO₂ changes tannin composition during wine aging, and the substantial formation of sulfonate-modified flavan-3-ols may provide an additional explanation for the reduction in astringency of aged red wines.

The impact of SO2 on wine flavanols and indoles in relation to wine style and age

Wine has one of the broadest chemical profiles, and the common oenological practice of adding the antioxidant and antimicrobial sulfur dioxide has a major impact on its metabolomic fingerprint. In this study, we investigated novel discovered oenological reactions primarily occurring between wine metabolites and sulfur dioxide. The sulfonated derivatives of epicatechin, procyanidin B2, indole acetic acid, indole lactic acid and tryptophol were synthesized and for the first time quantified in wine. Analysis of 32 metabolites in 195 commercial wines (1986-2016 vintages) suggested that sulfonation of tryptophan metabolites characterised white wines, in contrast to red wines, where sulfonation of flavanols was preferred. The chemical profile of the oldest wines was strongly characterised by sulfonated flavanols and indoles, indicating that could be fundamental metabolites in explaining quality in both red and white aged wines. These findings offer new prospects for more precise use of sulfur dioxide in winemaking.