Wine Constituents Research Articles

Determination and identification of polyphenols in wine using mass spectrometry techniques

Mass spectrometry is crucial for analysing physicochemical and sensory properties, including colour, astringency, taste, and flavour, predicting ageing characteristics, and addressing stability issues in wine. Polyphenols are key chemical constituents in wine that are associated with health benefits and improve circulatory conditions. Advances in mass spectrometry ionisation techniques such as matrix-assisted laser desorption and ionisation and direct analysis in real-time offer high sensitivity for identifying important polyphenolic constituents in wine. High-resolution mass spectrometry, in combination with liquid chromatography, accurately identify and quantify polyphenolic compounds, even at low concentrations, and provides the possibility for further retrospective analysis and non-targeted analysis using statistical methods of data analysis. Ambient mass spectrometry techniques such as paper spray and low-temperature plasma allow solventless analysis, determining the geographical origin, authentication, and quality control of wine samples. This review will explore the potential benefits of using mass spectrometry to identify various polyphenols and polymeric polyphenols in wine, as well as recent developments and applications. Additionally, we will discuss determining antioxidant activity and total polyphenol content in wine.

Compositional Consequences of Ultrafiltration Treatment of White and Red Wines.

Clarification and stabilisation processes are routinely performed post-fermentation to 'finish' wines, but traditional methods are slow and energy intensive, create waste, and can affect wine volume and quality. New methods that 'finish' wine rapidly, with higher recovery rates, and reduced waste and input costs, are therefore needed. Ultrafiltration is a separation process that fractionates liquids, nominally, according to molecular weight. By comparing the composition of permeate and retentate derived from pilot-scale fractionation of white and red wine using 75, 20, or 10 kDa membranes and different degrees of permeation (50, 80, 90, or 95%), this study sought to evaluate ultrafiltration as an innovative approach to the clarification and stabilisation of wine. Mass balance analysis confirmed that titratable acidity and alcohol were fractionated according to the degree of permeation; however, proteins, polysaccharides, and phenolic compounds (including anthocyanins for red wine) were concentrated in retentate due both to the membrane molecular weight cut-off (MWCO) specifications and degree of permeation. The retention of wine constituents smaller than the nominal MWCO suggests that interaction with other macromolecules or the membrane surface occurred. Red wine permeates were stripped of much of their essential character and were no longer considered commercially acceptable. In contrast, the removal of protein and phenolic compounds from white wine demonstrated the potential for ultrafiltration to remediate heat unstable or excessively phenolic wines. Findings enabled the identification of other winemaking applications of ultrafiltration technology that could enhance wine quality, process efficiency, and profitability.

Ispitivanje fizičko-hemijskih parametara kvaliteta voćnih vina proizvedenih u Republici Srbiji

Fruit wines are products obtained after the processing of fruit crops which are not grapes. Water and alcohol are the most abundant constituents of fruit wines, along with biologically active compounds which are present in small amounts. Taken together, they significantly affect the physicochemical quality parameters. Before market placement, it is important to determine the physicochemical quality parameters of fruit wines. This study deals with the determination of physicochemical quality parameters in blackberry and sour cherry fruit wines produced in Serbia. The total content of acids determined by titration was in the interval from 7.37 to 9.05 g/L express to mallic acid. The pH values were from 2.75 to 3.57. The content of free SO2 is important to prevent spoilage induced by microorganisms, and it was in the range from 12.52 to 15.21 mg/L. The ethanol content of samples was in the interval from 6.87 to 13.57 % v/v. The obtained values for ethanol content were in accordance with the initial content of sugar in vinification, which was in the range from 13.8 to 24.2 ° Brix. Total phenolic content of fruit wines was from 1895.77 to 2417.21 mg/L expressed as gallic acid equivalents. All the investigated physicochemical parameters of the analyzed fruit wines, except ethanol content, were in line with the National Regulations for Quality and Other Demands for Grape Wine (National Regulations). The obtained results indicate the quality of fruit and demonstrate that all the procedures applied during wine production were conducted properly to obtain a quality final product. Ethanol content was below the minimal limit in 5 of 11 analyzed samples according to the National Regulations. This can be explained by the fact that every fruit has a different composition of natural constituents, which is a crucial reason to adopt specific regulations related to quality and other requirements for fruit wines.

Grape Tartaric Acid: Chemistry, Function, Metabolism, and Regulation

Tartaric acid (TA) is the primary organic acid present in grapes and a fundamental constituent of wine, responsible for shaping its taste, aroma, and overall quality. This review presents a comprehensive overview of the advances made in previous investigations on grape tartaric acid. It elucidates the structural properties, distribution characteristics, biosynthesis, catabolism, and transcriptional regulation of grape tartaric acid, and also speculates on the regulatory mechanism of tartaric acid based on the modulation of ascorbic acid-related transcription factors. Furthermore, this review provides insights into the future research directions and objectives, with the goal of providing a reference for the analysis of the complete biosynthetic pathway of grape tartaric acid, thereby enabling precise regulation of tartaric acid.

Effect of the alcoholic strength of unaged wine distillates on the final composition of Brandy de Jerez aged in Sherry Casks®

Brandy is a spirit obtained from distilled wine that has an alcohol content equal to or greater than 36 % ABV (Alcohol by Volume). It undergoes an ageing process in oak wood casks with a capacity of up to 1000 L for a minimum of six months. During this process, a series of physicochemical and sensory changes take place that confer the initial wine distillate with a series of improvements to its sensory profile. Such changes are mainly determined by the intrinsic characteristics of the wood and by those associated with the manufacturing process of the casks. The previous use of the casks, ageing time and the alcoholic strength of the wine distillate are also important factors, among others. The casks, which will have previously contained some type of Sherry wine (such as Fino, Amontillado, Oloroso and Pedro Ximénez), are known as Sherry Casks® and they must be used in the production of Brandy de Jerez. During the ageing of Brandy de Jerez, Sherry Casks® contribute to the final brandy via the compounds that are both inherent to the wood they are made of and from the wine that they initially contained and that were retained in the wood pores. The alcohol content of the wine distillate to be aged significantly affects not only the quality of the brandy, but also the financial cost of the process. This study aimed to determine the influence on brandy of the alcoholic strength of wine distillates aged in static ageing systems using Sherry Casks®. Specifically, we assessed the physicochemical composition and sensory profile of Brandy de Jerez made from wine distillates with three different alcoholic strengths (40 %, 55 % and 68 % ABV) and aged for 24 months. The Brandy de Jerez with lower alcoholic strengths (40 % - 55 % ABV) were found to contain a higher concentration of polyphenolic compounds deriving from the wood as well as from the constituents of the cask-seasoning Sherry wine. The brandies with higher alcoholic strengths exhibited a marked colour change, while the 40 % and 55 % ABV brandies were perceived to have the best sensory characteristics.

The Influence of Melatonin Treatment in the Vinification of Feteasca Neagra and Cabernet Sauvignon Wines on the Profile of Polyphenolic Compounds and Antioxidant Activity.

Until recently, the main antioxidant role among wine constituents was attributed to polyphenolic compounds, but once the presence of melatonin in wines was confirmed, an interesting new field of research opened up due to its possible synergistic effects with other antioxidants in the winemaking process, which may lead to a change in the profile of polyphenolic compounds and antioxidant activity. In order to investigate the evolution of active principles from the phenylpropanoid metabolism associated with the synergistic effects of melatonin, for the first time, a melatonin treatment was performed in the pre-stage of the different winemaking processes of Feteasca Neagra and Cabernet Sauvignon wines with different melatonin concentrations. After comparing the acquired results for the evolution of the polyphenolic compound profile and antioxidant activity of treated wines, we ascertained an increase in the antioxidant compound concentrations, especially in resveratrol, quercetin, and cyanidin-3-glucoside, directly proportional to the used melatonin concentration; an intensification in activity of PAL and C4H enzymes; and the modification in the expression of specific anthocyanin biosynthesis genes, especially UDP-D-glucose-flavonoid-3-O-glycosyltransferase. It was also shown that the application of melatonin in the pre-stage of the winemaking process can be successfully used to obtain red wines with increased antioxidant activity (almost 14%).

Differential Effects of White Wine and Ethanol Consumption on Survival of Rats after a Myocardial Infarction

Studies of the cardioprotective effects of wine are mainly focused on red wines, due to their much higher content of bioactive compounds relative to white wines. Although some studies indicate a cardioprotective effect of white wine, there is no clear consensus on the existence of additional benefits of white wine over ethanol. The aim of this study was to determine and compare the effects of moderate consumption of white wine and ethanol on the survival of rats subjected to surgically induced myocardial infarction (MI). Male Sprague Dawley rats (n = 74) were randomized into three groups: water only, white wine or a 13% v/v ethanol/water solution. After a four-week drinking period, MI was induced by ligating the left anterior descending artery. The survival rate was highest in the wine group (72.2%), and lowest in the water only group (47.8%). There was no statistically significant difference in survival between the ethanol and water groups. An analysis linking drinking volumes to survival outcomes revealed that lower ethanol consumption was more prevalent in rats that survived, indicating an upper limit for the protective effects of ethanol. An opposite finding was noticed in the wine group, where no deaths occurred in rats with an average daily white wine consumption of approximately 10 mL or more. We conclude that moderate consumption of white wine has a positive effect on survival after a myocardial infarction, which cannot be attributed only to ethanol, but also to other white wine constituents.

<sup>1</sup>H-NMR metabolomics for wine screening and analysis

The number of metabolomic studies has grown steadily over the last twenty years. Among the fields of application, food sciences are broadly represented. Proton NMR (1H-NMR) is a commonly used technique for metabolomics and is particularly suitable for wine analysis, because the major wine constituents are highly dependent on biotic and abiotic conditions. 1H-NMR-based metabolomics were used first to guarantee the authenticity of wines, and more recently to determine the impact of viticultural or oenological practices using both targeted and untargeted protocols. This state-of-the-art review covers the different analytical methodologies developed to ensure wine traceability from sample preparation to 1H-NMR spectrum analysis. The potential applications of 1H-NMR spectroscopy in oenology, from wine authenticity control to the monitoring of winemaking, are described. The challenges and perspectives of the deployment of NMR for oenological monitoring are also discussed.

Grape-derived pectic polysaccharides alter the tannin and pigment composition of Cabernet Sauvignon red wines

Tannins, anthocyanins, and polymeric pigments are essential phenolic constituents of red wine because they provide color, color stability, and mouthfeel properties like astringency. The behavior of these compounds is significantly affected by pectic polysaccharides, whereby the extent of their influence on red wine quality depends on their structural features and their interactions with the polyphenols. In the present study, the composition of the pectic polysaccharides of commercially available Cabernet Sauvignon wines and their impact on anthocyanin, tannin, and polymeric pigment analyses was characterized. This was accomplished by preparation of polysaccharide deprived wines and comparison of the polyphenolic composition of both, the wines and their corresponding polysaccharide-free counterparts. The results show that the cell wall fragments enhance the spectral absorbance of anthocyanins by facilitating anthocyanin self-association, leading to a co-pigmentation-like effect. Low molecular weight pectins like rhamnogalacturonan II and polygalacturonic acids with a low degree of esterification are assumed to form soluble complexes with anthocyanins and also prevent protein precipitation of tannins, which was reduced by 6–13%. High molecular weight pectins with a high degree of esterification lead to the increased precipitability of pigments and tannins by a factor of 1.3 to 32.4 and 1.1 to 1.9, respectively, seemingly impairing the incorporation of anthocyanins in tannins to form precipitable polymeric pigments that are responsible for the longevity of red wine color. The increased precipitability of the pigments due to the interactions with the polysaccharides may indicate the formation of pigmented yet non-covalent aggregates that show comparable properties to the covalently formed precipitable pigments. The formation of those non-covalent structures may affect red wine color stability and astringency.

Multivariate Statistical Analysis for Mutual Dependence Assessment of Selected Polyphenols, Organic Acids and Metals in Cool-Climate Wines.

Polyphenols, organic acids and metal ions are an important group of compounds that affect the human health and quality of food and beverage products, including wines. It is known that a specific correlation between these groups exist. While wines coming from the New World and the Old World countries are extensively studied, wines coming from cool-climate countries are rarely discussed in the literature. One of the goals of this study was to determine the elemental composition of the wine samples, which later on, together as polyphenols and organic acids content, was used as input data for chemometric analysis. The multivariate statistical approach was applied in order to find specific correlations between the selected group of compounds in the cool-climate wines and the features that distinguish the most and differ between red and white wines and rosé wines. Moreover, special attention was paid to resveratrol and its correlation with selected wine constituents.

A review on the comparative study of nutraceutically activated fruits and herbs based wines

Nowadays, fruits and herbs wine is a boon for the alcoholic beverage industry since it has a plethora of secondary metabolites (bioactives) with numerous pharmacological properties. The article aims to provide an overview of the possibility of making wine from a variety of nutraceutically active herbs and fruits. The different databases have been used to compile the information. Wine can be made from tropical, subtropical, and temperate fruits that are highly perishable, nutritionally diverse, and underutilised, such as raspberries, pomegranates, sweet potatoes, papaya, pineapples, and kiwi fruit. Herbal wine is beneficial to the alcoholic beverage industry because it has a large number of secondary metabolites (bioactives) with a variety of medicinal properties. Herbal and fruit wine provide biological functions and health benefits such as antioxidants, anti-inflammatory activity, anticancer, anti-aging, and protection against cardiovascular problems, diabetes, obesity, and neurodegenerative disorders. Among herbal and fruit wine constituents, phenolic compounds are important in conferring health benefits. Most significantly, phenolic substances like flavanols, flavanones, flavones, tannins, anthocyanins, hydroxycinnamic acids, hydroxybenzoic acids, and resveratrol can help prevent heart disease, cancer, diabetes, inflammation, and other chronic diseases. This study focuses on the comparative health benefits of the bioactive chemicals which are present in the fruits and herbal wines. Wine includes physiologically active components that have the potential to improve consumer’s health. Various herbs and fruits used for winemaking and their medicinal applications have been discussed in this paper.

Elucidating the Color of Rosé Wines Using Polyphenol-Targeted Metabolomics.

The color of rosé wines is extremely diverse and a key element in their marketing. It is due to the presence of anthocyanins and of additional pigments derived from them and from other wine constituents. To explore the pigment composition and determine its links with color, 268 commercial rosé wines were analysed. The concentration of 125 polyphenolic compounds was determined by a targeted metabolomics approach using ultra high-performance liquid chromatography coupled to triple quadrupole mass spectrometry (UHPLC-QqQ-MS) analysis in the Multiple Reaction Monitoring (MRM) mode and the color characterised by spectrophotometry and CieLab parameters. Chemometrics analysis of the composition and color data showed that although color intensity is primarily determined by polyphenol extraction (especially anthocyanins and flavanols) from the grapes, different color styles correspond to different pigment compositions. The salmon shade of light rosé wines is mostly due to pyranoanthocyanin pigments, resulting from reactions of anthocyanins with phenolic acids and pyruvic acid, a yeast metabolite. Redness of intermediate color wines is related to anthocyanins and carboxypoyranoanthocyanins and that of dark rosé wines to products of anthocyanin reactions with flavanols while yellowness of these wines is associated to oxidation.

Impact of commercial scale ultrafiltration on the composition of white and rosé wine

Ultrafiltration (UF) was performed on six white and rosé wines, at commercial scale (5400–71,000 L), to remove phenolic compounds associated with astringency. Dynamic UF parameters (permeate flux, transmembrane pressure, temperature) were monitored during filtration, and wine composition compared before and after treatment. Over 90% wine permeation was achieved although flux declined progressively throughout UF and dropped significantly after 80% fractionation. Wine macromolecules, especially phenolics and proteins, were substantially concentrated in retentate, such that the resulting permeate achieved clarification and heat stabilization specifications eliminating the need for fining. Other wine compositional properties (pH, free and total SO2, volatile acidity, and viscosity) were not significantly affected. Membrane fouling resulted in the rejection of small wine constituents (sugars, acids, and low molecular weight phenolics) suggesting complex membrane/solute interactions. To our knowledge, this is the first study to demonstrate the efficacy of UF in producing clarified and stabilized permeate, which reduced the negative effects of excess phenolics and proteins in wine.

Chemical Composition and Polyphenolic Compounds of Red Wines: Their Antioxidant Activities and Effects on Human Health—A Review

Red wine, an alcoholic beverage is composed of a spectrum of complex compounds such as water, alcohol, glycerol, organic acid, carbohydrates, polyphenols, and minerals as well as volatile compounds. Major factors that affect the levels of phenolic compounds in red wines are the variety of grapes and the storage of the wines. Among the constituents of red wine, phenolic compounds play a crucial role in attributes including color and mouthfeel and confer beneficial properties on health. Most importantly, phenolic compounds such as flavanols, flavonols, flavanones, flavones, tannins, anthocyanins, hydroxycinnamic acids, hydroxybenzoic acids, and resveratrol can prevent the development of cardiovascular diseases, cancers, diabetes, inflammation, and some other chronic diseases.

Strategies for the identification and sensory evaluation of volatile constituents in wine.

Wine aroma, which stems from complex perceptual and cognitive processes, is initially driven by a multitude of naturally occurring volatile constituents. Its interpretation depends on the characterization of relevant volatile constituents. With large numbers of volatile constituents already identified, the search for unknown volatiles in wine has become increasingly challenging. However, the opportunities to discover unknown volatile compounds contributing to the wine volatilome are still of great interest, as demonstrated by the recent identification of highly odorous trace (µg/L) to ultra-trace (ng/L) volatile compounds in wine. This review provides an overview of both existing strategies and future directions on identifying unknown volatile constituents in wine. Chemical identification, including sample extraction, fractionation, gas chromatography, olfactometry, and mass spectrometry, is comprehensively covered. In addition, this review also focuses on aspects related to sensory-guided wine selection, authentic reference standards, artifacts and interferences, and the evaluation of the sensory significance of discovered wine volatiles. Powerful key volatile odorants present at ultra-trace levels, for which these analytical approaches have been successfully applied, are discussed. Research areas where novel wine volatiles are likely to be identified are pointed out. The importance of perceptual interaction phenomena is emphasized. Finally, future avenues for the exploration of yet unknown wine volatiles by coupling analytical approaches and sensory evaluation are suggested.

Sensory assessment of grape polyphenolic fractions: an insight into the effects of anthocyanins on in-mouth perceptions

Anthocyanins are extracted from grape skins during maceration and are responsible for the red colour of wine. Their contribution to in-mouth sensations is mainly related to their interactions with condensed tannins, which are largely responsible for wine astringency and mouthfeel-related features. Recently, the influence of several groups of polyphenols, together with other relevant non-phenolic wine constituents,was investigated in terms of their ability to modify the sensory perception of condensed tannins. The aim of this study was to investigate the influence of three acylation groups of anthocyanins (glucoside, acetylglucoside, and p-coumaroylglucoside) extracted from grape skins on in-mouth related features. An extract of total anthocyanins and their individual fractions were tasted using different sensory approaches (triangle test, check-all-that apply and descriptive analysis) and compared to polyphenols extracted from grape skins and seeds. The investigated sensations were overall astringency and astringency sub-qualities, which were divided into two groups: sensation during tasting (in-mouth, particulates) and sensation after expectoration (surface smoothness). Bitterness was also studied. Anthocyanin fractions were added to skin and seed extracts and tasted as mixtures to find out if anthocyanins modify in-mouth perception. Although the anthocyanin fractions showed a low sensory impact, total anthocyanins and the glucoside fraction were perceived at the concentration ranges found in wines (400 mg/L), and they were found to influence astringency intensity and soft astringency sub-qualities, such as “velvety” and “chalky”. The addition of glucoside anthocyanin (400 mg/L) to skin and seed extract (1000 mg/L) modified in-mouth perception; in particular, seed extract was perceived as being more astringent and was characterised by harsher astringency sub-qualities (surface smoothness and particulates). In contrast, the addition of glucoside anthocyanin to the skin extract led to lower surface smoothness, although the intensity of overall astringency was unchanged. These results confirm that the presence of anthocyanins can modify the perception of in-mouth sensations and interact to different extents with other polyphenols, thus leading to the modification of the intensity of astringency and its sub-qualities.

Effects of alcohol consumption in general, and wine in particular, on the risk of cancer development: a review

Since 1988, alcohol has been classified as a Group 1 carcinogen, the highest level of risk, by the International Agency for Research on Cancer (IARC). In fact, alcohol consumption is the third leading risk factor for disease and mortality in Europe. It accounts for 4.65 % of the global burden of both injury and disease, making it one of the most preventable causes of injury and death. Tissues in closest contact with alcohol when it is ingested, such as those of the oral cavity, pharynx, esophagus and larynx, have at greater risk of becoming cancerous than other body tissues. The consumption of alcohol is also associated with an increased risk of stomach, colon, rectum, liver, female breast and ovarian cancers. Conversely, recent studies suggest that red wine components inhibit colony formation of human breast cancer and esophageal carcinoma cells, suggesting that wine-derived phenolic compounds may be inhibitory, in contrast to the alcohol component of wine. Because of a lack of systematic studies dealing with the different types of cancer and alcoholic beverages and wine in particular, in this narrative review we summarize the general risk of cancer linked to the consumption of alcoholic beverages, including wine, according to type of cancer, with 140 extracted relevant references from 1966 to 2020. Mostly epidemiological studies concerning large cohorts have been selected. For the cancers of the upper aerodigestive tract, liver, colorectum, breast cancer, pancreatic, prostate, an excessive consumption and/or misuse of alcoholic beverages is correlated with increased risk. Conversely a probable decreased risk has been found for renal/kidney cancers, as well as for Non-Hodgkin lymphomas, such as thyroid lymphomas, associated with the moderate consumption of alcoholic beverages. There is no evidence of ovarian, gastric, head and neck, and lung cancer being linked to the moderate consumption of alcoholic beverages. Cancer is a multifactorial disease, and many factors contribute to effects on health status, usually being both genetic and environmental. Habits (smoking, dietary/lifestyle pattern/ habits, physical activity), should also be taken into account when defining appropriate consumption frequencies for different types of alcoholic drink (wine, beer, spirits). Further research is needed related to wine consumption in the context of a healthy dietary and lifestyle pattern given health-promoting constituents of wine and its effects on cancer incidence.

Antimicrobial Activity of Selected Red and White Wines against Escherichia coli: In Vitro Inhibition Using Fish as Food Matrix.

Five different wines (standard Graševina, macerated Graševina with and without sulfur, rosé, and standard Plavac Mali), all typical Croatian wines, were tested to determine the antimicrobial activity against two Escherichia coli bacterial strains (ATCC® 25922 and ATCC® 8739) in vitro and using sea bass (Dicentrarchus labrax) fillets as food matrix. The chemical composition of wines (pH, acidity, alcohol, total phenolics, anthocyanins, tannins, and sulfur content) and antimicrobial activity (minimal inhibitory concentration (MIC), agar-well diffusion method) were determined. The total phenolic content of the wines ranged from 305–3210 mg gallic acid equivalents per liter (GAE/L), and did not correlate to antimicrobial activity. The two wines with the lowest phenolic content (standard Graševina and rosé) had the lowest MIC values (122 and 429 mg GAE/L). A specific relation between the winemaking process and a particular MIC value was not established. There was also no relation found between the pH value, ethanol content, sulfur, or phenolics in regards to the antimicrobial effect. In fish fillets marinated in wine + water mixture (v/v = 1:1) and inoculated with 7 log colony forming units (CFU)/25 g the growth of bacteria was reduced after three days of storage at 4 °C. Subsequent storage resulted in the growth of bacteria in all samples, with the lowest growth of E. coli ATCC® 25922 in macerated Graševina and E. coli ATCC® 8739 in standard Graševina. All wines showed the capacity to reduce the number and growth of heavily infected sea bass filets, but correlation with specific wine constituents was not found. Taking into account the numerous reactive mechanisms between food and wine, all in vitro studies in controlled laboratory conditions should be further verified in the relevant environment, and additional research is needed to clarify the role of individual wine components in the mechanism of antimicrobial activity.

Cultivar, site or harvest date: the gordian knot of wine terroir.

The complex interactions of vine cultivars, and localised regional climate associated with specific vineyard sites are important attributes to the concept of terroir and significant contributors to grape maturity and wine sensory profiles. An improved understanding of the influence of each factor and their interactions is a challenging conundrum, and will enable more efficient production targeting specific wine styles. To characterise the metabolic flux of grape berries and resulting wines to characterise the relative impact of site specific climate, cultivar, and grape maturity based upon berry sugar accumulation models that consistently target specific wine styles. A spatial and temporal study of grape and wine composition was undertaken for two important cultivars in two distinct regions of New South Wales. Measures of composition and wine sensory ratings were simultaneously analysed using a multiblock algorithm taking advantage of the ANOVA framework to identify important contributions to wine style arising from grape maturity, vineyard site and cultivar. A consistent flux of grape and wine constituents is evident for wine made from sequentially harvested grapes from the same vineyard with increasing levels of grape maturity. Contributions of region and vineyard site to wine style could also be elucidated. Differences in metabolite flux in grapes and resulting wines between cultivars growing in similar conditions are evident. The combination of a metabolomics and multiblock data decomposition approach may be successfully used to profile and elucidate the contribution of abiotic factors to grape and wine composition and provide improved understanding of the terroir concept.

The Secondary Structure of a Major Wine Protein is Modified upon Interaction with Polyphenols.

Polyphenols are an important constituent of wines and they are largely studied due to their antioxidant properties and for their effects on wine quality and stability, which is also related to their capacity to bind to proteins. The effects of some selected polyphenols, including procyanidins B1 and B2, tannic acid, quercetin, and rutin, as well as those of a total white wine procyanidin extract on the conformational properties of the major wine protein VVTL1 (Vitis vinifera Thaumatin-Like-1) were investigated by Synchrotron Radiation Circular Dichroism (SRCD). Results showed that VVTL1 interacts with polyphenols as demonstrated by the changes in the secondary (far-UV) and tertiary (near-UV) structures, which were differently affected by different polyphenols. Additionally, polyphenols modified the two melting temperatures (TM) that were found for VVTL1 (32.2 °C and 53.9 °C for the protein alone). The circular dichroism (CD) spectra in the near-UV region revealed an involvement of the aromatic side-chains of the protein in the interaction with phenolics. The data demonstrate the existence of an interaction between polyphenols and VVTL1, which results in modification of its thermal and UV denaturation pattern. This information can be useful in understanding the behavior of wine proteins in presence of polyphenols, thus giving new insights on the phenomena that are involved in wine stability.