Wine evolution during bottle aging, studied by 1H NMR spectroscopy and multivariate statistical analysis

Fusing 1H NMR and Raman experimental data for the improvement of wine recognition models

The present study proposes the development of new wine recognition models based on Artificial Intelligence (AI) applied to the mid-level data fusion of 1H NMR and Raman data. In this regard, a supervised machine learning method, namely Support Vector Machines (SVMs), was applied for classifying wine samples with respect to the cultivar, vintage, and geographical origin. Because the association between the two data sources generated an input space with a high dimensionality, a feature selection algorithm was employed to identify the most relevant discriminant markers for each wine classification criterion, before SVM modeling. The proposed data processing strategy allowed the classification of the wine sample set with accuracies up to 100% in both cross-validation and on an independent test set and highlighted the efficiency of 1H NMR and Raman data fusion as opposed to the use of a single-source data for differentiating wine concerning the cultivar and vintage.

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.

Exploring potential correlations between bacterial communities, organic acids, and volatile metabolites of traditional fermented sauerkraut collected from different regions of Heilongjiang Province in Northeast China

In this study, the bacterial communities and flavor metabolites of 27 traditional naturally fermented sauerkraut samples collected from nine regions of Heilongjiang Province in Northeast China were investigated. The dominant genera were Lactobacillus, Pseudomonas, Alcaligenes, Arcobacter, Pseudarcobacter, Lactococcus, Comamonas, Pediococcus, Prevotella, and Insolitispirillum. A total of 148 volatile compounds were detected in seven categories; esters and acids were the most abundant volatiles. Additionally, the highest content (15.96 mg/g) of lactic acid was detected in YC1. Acetic acid, oleic acid, palmitic acid, elaidic acid, and dehydroacetic acid were the key differential volatile compounds, which may be related to the bacterial communities. Spearman's correlation analysis revealed that Lactococcus and Lactobacillus were significantly positively correlated with flavor metabolites, suggesting that they may play a more significant role in flavor formation. The results of this study can help in the development of better quality of fermented vegetables.

Variations in physicochemical characteristics, antioxidant activity, phenolic and volatile profiles, and sensory attributes of tea-flavored Chardonnay wine during bottle aging

A novel Chardonnay wine flavored with either green tea or black tea was subjected to bottle aging for 9 months, and the physicochemical properties, antioxidant capacity, total phenolic content, volatile content and sensory properties were monitored. There were 272 phenolic and non-phenolic compounds characterized in the aged Chardonnay wines, including newly formed 9, 1, 3 and 8 phenolic compounds and 10, 6, 1 and 6 non-phenolic compounds after aging for 1, 3, 6 and 9 months, respectively. For all the aged wines, catechin was determined as the most abundant phenolic compound, and epigallocatechin mainly contributed toward the antioxidant power. A total of 54 volatile compounds were identified in the aged Chardonnay wines, including 17 odor-active compounds. The aging process diminished floral and fruity odors, but intensified green odor. The consumer study revealed the highest consumer liking for 1% (w/v) black tea infused wine. This study revealed the quality and bioactivity of this novel flavored wine type during aging which is critical to understand the shelf-life and functionality of the product.

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.

Study of the Stability of Wine Samples for 1H-NMR Metabolomic Profile Analysis through Chemometrics Methods

Wine is a temperature, light, and oxygen-sensitive product, so its physicochemical characteristics can be modified by variations in temperature and time when samples are either sampled, transported, and/or analyzed. These changes can alter its metabolomic fingerprinting, impacting further classification tasks and quality/quantitative analyses. For these reasons, the aim of this work is to compare and analyze the information obtained by different chemometric methods used in a complementary form (PCA, ASCA, and PARAFAC) to study 1H-NMR spectra variations of four red wine samples kept at different temperatures and time lapses. In conjunction, distinctive changes in the spectra are satisfactorily tracked with each chemometric method. The chemometric analyses reveal variations related to the wine sample, temperature, and time, as well as the interactions among these factors. Moreover, the magnitude and statistical significance of the effects are satisfactorily accounted for by ASCA, while the time-related effects variations are encountered by PARAFAC modeling. Acetaldehyde, formic acid, polyphenols, carbohydrates, lactic acid, ethyl lactate, methanol, choline, succinic acid, proline, acetoin, acetic acid, 1,3-propanediol, isopentanol, and some amino acids are identified as some of the metabolites which present the most important variations.

Untargeted metabolomics analysis based on LC-IM-QTOF-MS for discriminating geographical origin and vintage of Chinese red wine

Identifying wine geographical origin and vintage is vital due to the abundance of fraudulent activity associated with wine mislabeling of region and vintage. In this study, an untargeted metabolomic approach based on liquid chromatography/ion mobility quadrupole time-of-flight mass spectrometry (LC-IM-QTOF-MS) was used to discriminate wine geographical origin and vintage. Wines were well discriminated according to region and vintage with orthogonal partial least squares-discriminant analysis (OPLS-DA). The differential metabolites subsequently were screened by OPLS-DA with pairwise modeling. 42 and 48 compounds in positive and negative ionization modes were screened as differential metabolitesfor the discrimination of different wine regions, and 37 and 35 compounds were screened for wine vintage. Furthermore, new OPLS-DA models were performed using these compounds, and the external verification trial showed excellent practicality with an accuracy over 84.2%. This study indicated that LC-IM-QTOF-MS-based untargeted metabolomics was a feasible tool for wine geographical origin and vintage discrimination.

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.

Valorization of Traditional Alcoholic Beverages: The Study of the Sicilian Amarena Wine during Bottle Aging

Traditional alcoholic beverages have always been part of the Mediterranean culture and, lately, they have been re-evaluated to valorize both the territory and local customs. In this study, the Amarena wine, a fortified wine included in the national list of the traditional agri-food products, was characterized during bottle aging for oenological parameters, chromaticity, volatiles, and inorganic elements. Then, experimental data were visually interpreted by a principal component analysis (PCA). PCA revealed that most of oenological parameters (i.e., alcoholic grade, total dry extract, sugars, organic acids, and phenolic compounds) had a scarce discriminating power. Additionally, ethyl esters were only present in younger products, while remaining at quite constant levels. Conversely, certain metals (i.e., Mg, Na, Mn, Zn, and Cu), chromatic properties, and pH differentiated older Amarena bottles from the younger counterpart. Particularly, acetaldehyde and furanic compounds proved to be valid aging markers. A sensorial analysis highlighted that fruity and floral odors and flavors characterized younger beverages, while dried fruity, nutty, and spicy notes were displayed by older products, along with the valuable attribute of “oxidized” typically observed in aged Sherry wines. Overall, this study may encourage the production and commercialization of the Amarena wine, thus preserving the cultural heritage of the Mediterranean area.

Monitoring of the Rioja red wine production process by 1 H-NMR spectroscopy

BACKGROUND

As an inherently quantitative and unbiased analytical technique, proton nuclear magnetic resonance (¹ H-NMR) provides an excellent method to monitor the quality of food and beverages, and a sensitive and informative tool to study the winemaking process.

RESULTS

By using NMR, it is possible to monitor quantitative changes in wine metabolites (amino acids, organic acids and some phenolic compounds) during the winemaking process, including wine ageing. This study shows an increase in the concentration of the phenols at the beginning of alcoholic fermentation, as well as a stabilization and slight increase in gallic acid and a slight decrease in resveratrol during the oak barrel ageing step.

CONCLUSION

This study demonstrates the potential of NMR as a process analytical technology (PAT) tool in the wine industry, by monitoring amino acids, organic acids and three polyphenols - gallic acid, catechin and resveratrol - during the winemaking process. This study of the time course evolution of wine has been conducted in a commercial winery rather than an experimental laboratory, demonstrating the capacity of this technique in commercial winemaking production. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Exploring Use of the Metschnikowia pulcherrima Clade to Improve Properties of Fruit Wines

Mixed fermentation using Saccharomyces cerevisiae and non-Saccharomyces yeasts as starter cultures is well known to improve the complexity of wines and accentuate their characteristics. This study examines the use of controlled mixed fermentations with the Metschnikowia pulcherrima clade, Saccharomyces cerevisiae Tokay, and non-conventional yeasts: Wickerhamomyces anomalus and Dekkera bruxellensis. We investigated the assimilation profiles, enzyme fingerprinting, and metabolic profiles of yeast species, both individually and in mixed systems. The chemical complexity of apple wines was improved using the M. pulcherrima clade as co-starters. M. pulcherrima with S. cerevisiae produced a wine with a lower ethanol content, similar glycerol level, and a higher level of volatilome. However, inoculation with the Dekkera and Wickerhamomyces strains may slightly reduce this effect. The final beneficial effect of co-fermentation with M. pulcherrima may also depend on the type of fruit must.

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.

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.

Recent advances in NMR-based metabolomics of alcoholic beverages

Alcoholic beverages have a complex chemistry that can be influenced by their alcoholic content, origin, fermentation process, additives, and contaminants. The complex composition of these beverages leave them susceptible to fraud, potentially compromising their authenticity, quality, and market value, thus increasing risks to consumers' health. In recent years, intensive studies have been carried out on alcoholic beverages using different analytical techniques to evaluate the authenticity, variety, age, and fermentation processes that were used. Among these techniques, NMR-based metabolomics holds promise in profiling the chemistry of alcoholic beverages, especially in Asia where metabolomics studies on alcoholic beverages remain limited.

Characterization of Moravian Wines by Selected Chemical Parameters

Knowledge of analytical values in wines is essential to ensure product safety and compliance with legislation, and it is also essential to understand the various technologies in wine production. The aim of this work was to evaluate the analytical parameters of bottled Moravian wines from the Znojmo sub-region, from harvests 2015 and 2016. Basic oenological parameters and biologically active substances were evaluated. Moreover, we evaluated conditions during bottle aging in wines from harvest 2016. The results of the basic analytical values such as total phenolic acid (TPA), total sulfur dioxide (SO2), pH, actual alcohol content (EtOH), and titratable acidity (TA) were in accordance with generally known values in wines and met the legislative requirements within oenological practices. Biologically active substances, such as gallic acid, trans-caffeic acid (TCA), trans-p-coumaric acid (TPCA), rutin, ferulic acid (FA), myricetin, resveratrol, and quercetin were identified. Comparing the analytical values of individual types of wine leads to a better understanding of winemaking technology and the development of wine as such. The subject of the study was also the monitoring of produced grape pomace incurred during wine production harvest 2015 with the indication of possibilities of its further use.

Combination of two analytical techniques improves wine classification by Vineyard, Region, and vintage

Three important wine parameters: vineyard, region, and vintage year, were evaluated using fifteen Vitis vinifera L. 'Pinot noir' wines derived from the same scion clone (Pinot noir 667). These wines were produced from two vintage years (2015 and 2016) and eight different regions along the Pacific Coast of the United States. We successfully improved the classification of the selected Pinot noir wines by combining an untargeted 1D ¹H NMR analysis with a targeted peptide based differential sensing array. NMR spectroscopy was used to evaluate the chemical fingerprint of the wines, whereas the peptide-based sensing array is known to mimic the senses of taste, smell, and palate texture by characterizing the phenolic profile. Multivariate and univariate statistical analyses of the combined NMR and differential sensing array dataset classified the genetically identical Pinot noir wines on the basis of distinctive metabolic signatures associated with the region of growth, vineyard, and vintage year.

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.

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.

NMR spectroscopy in wine authentication: An official control perspective

Wine authentication is vital in identifying malpractice and fraud, and various physical and chemical analytical techniques have been employed for this purpose. Besides wet chemistry, these include chromatography, isotopic ratio mass spectrometry, optical spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy, which have been applied in recent years in combination with chemometric approaches. For many years, ² H NMR spectroscopy was the method of choice and achieved official recognition in the detection of sugar addition to grape products. Recently, ¹ H NMR spectroscopy, a simpler and faster method (in terms of sample preparation), has gathered more and more attention in wine analysis, even if it still lacks official recognition. This technique makes targeted quantitative determination of wine ingredients and nontargeted detection of the metabolomic fingerprint of a wine sample possible. This review summarizes the possibilities and limitations of ¹ H NMR spectroscopy in analytical wine authentication, by reviewing its applications as reported in the literature. Examples of commercial and open-source solutions combining NMR spectroscopy and chemometrics are also examined herein, together with its opportunities of becoming an official method.

Comprehensive Classification and Regression Modeling of Wine Samples Using 1H NMR Spectra

Recently, ¹H NMR (nuclear magnetic resonance) spectroscopy was presented as a viable option for the quality assurance of foods and beverages, such as wine products. Here, a complex chemometric analysis of red and white wine samples was carried out based on their ¹H NMR spectra. Extreme gradient boosting (XGBoost) machine learning algorithm was applied for the wine variety classification with an iterative double cross-validation loop, developed during the present work. In the case of red wines, Cabernet Franc, Merlot and Blue Frankish samples were successfully classified. Three very common white wine varieties were selected and classified: Chardonnay, Sauvignon Blanc and Riesling. The models were robust and were validated against overfitting with iterative randomization tests. Moreover, four novel partial least-squares (PLS) regression models were constructed to predict the major quantitative parameters of the wines: density, total alcohol, total sugar and total SO₂ concentrations. All the models performed successfully, with R² values above 0.80 in almost every case, providing additional information about the wine samples for the quality control of the products. ¹H NMR spectra combined with chemometric modeling can be a good and reliable candidate for the replacement of the time-consuming traditional standards, not just in wine analysis, but also in other aspects of food science.

Application of Ultraviolet-Visible Absorption Spectroscopy with Machine Learning Techniques for the Classification of Cretan Wines

The present study was aimed at the identification, differentiation and characterization of red and white Cretan wines, which are described with Protected Geographical Indication (PGI), using ultraviolet–visible absorption spectroscopy. Specifically, the grape variety, the wine aging process and the role of barrel/container type were investigated. The combination of spectroscopic results with machine learning-based modelling demonstrated the use of absorption spectroscopy as a facile and low-cost technique in wine analysis. In this study, a clear discrimination among grape varieties was revealed. Moreover, a grouping of samples according to aging period and container type of maturation was accomplished, for the first time.

Identification of the Volatile Compounds and Sensory Attributes of Long-Term Aging Vin Santo Wine from Malvasia di Candia Aromatic Grapes

In an effort to offer a contribution to fill the gap of knowledge about the relationship between the sensory properties and aromatic profile of Malvasia grapes, the present work was aimed at evaluating volatile compounds, aroma, and sensory attributes of long-term aging (15 years) Vin Santo wine obtained from Malvasia di Candia aromatica grapes. In this article, the aromatic profile are studied using gas chromatography-mass spectrometry (GC-MS), gas chromatography with flame ionization detection (GC-FID), and sensory analysis by involving a panel of trained assessors to explore the sensory profile resulting after long-term aging (up to 15 years). The GC-MS and GC-FID analyses of wines allowed the identification and semi-quantification of twenty-seven volatiles belonging to 12 conventional groups of compounds. From a sensory perspective, the Vin Santo wines analyzed in this study presented a very complex sensory profile characterized by 19 sensory descriptors of which 14 related to olfactory terms. The relationship between sensory and GC-FID data deduced from three samples representing nearly three years in the past 15 years was investigated by means of Partial Least Square (PLS) modeling, showing that specific volatile compounds could predict a specific orthonasal and/or retronasal odor perceived by the trained panel of assessors, clearly differentiating the Vin Santo vintages. Identifying the main volatiles and aromas of long-term Vin Santo wine may be helpful to winemakers, since wine aging sensory properties are often associated with a prestigious image and contribute to defining wine quality.

Qualitative Factor-Based Comparison of NMR, Targeted and Untargeted GC-MS and LC-MS on the Metabolomic Profiles of Rioja and Priorat Red Wines

Wine origin and ageing are two factors related to wine quality which in turn is associated to wine metabolome. Currently, new metabolomic techniques and proper statistics procedures allow accurate profiling of wine metabolome. Thus, the main goal was to evaluate different metabolomic methodologies on their ability to provide patterns on the wine metabolome based on selected factors, such as ageing of barrel-aged wine (factor time), prior usage of the barrels (factor barrel-type), and differences between wine ageing in barrels or glass bottles (factor bottled-wine). In the current study, we implement NMR, targeted and untargeted GC-MS and LC-MS metabolomic analytical techniques so as to gain insights into the volatile and nonvolatile wine metabolome composition of red wines from two cellars located in the only two Spanish Qualified Appellations of Origin; DOQ Priorat and DOCa Rioja regions. Overall, 95 differentially significant metabolites were identified facilitating the evaluation of the analytical methodologies performance and finding common trends of those metabolites depending on the considered factor. The results did not favor NMR as an effective technique on the current dataset whereas suggested LC-MS as an adequate technique for revealing differences based on the factor time, targeted GC-MS on the factor barrel-type, and untargeted GC-MS on the factor bottled-wine. Thus, a combination of different metabolomic techniques is necessary for a complete overview of the metabolome changes. These results ease the selection of the correct methodology depending on the specific factor investigated.

Bioactive Compounds and Metabolites from Grapes and Red Wine in Breast Cancer Chemoprevention and Therapy

Phytochemicals and their metabolites are not considered essential nutrients in humans, although an increasing number of well-conducted studies are linking their higher intake with a lower incidence of non-communicable diseases, including cancer. This review summarizes the current findings concerning the molecular mechanisms of bioactive compounds from grapes and red wine and their metabolites on breast cancer-the most commonly occurring cancer in women-chemoprevention and treatment. Flavonoid compounds like flavonols, monomeric catechins, proanthocyanidins, anthocyanins, anthocyanidins and non-flavonoid phenolic compounds, such as resveratrol, as well as their metabolites, are discussed with respect to structure and metabolism/bioavailability. In addition, a broad discussion regarding in vitro, in vivo and clinical trials about the chemoprevention and therapy using these molecules is presented.

Trunk Girdling Increased Stomatal Conductance in Cabernet Sauvignon Grapevines, Reduced Glutamine, and Increased Malvidin-3-Glucoside and Quercetin-3-Glucoside Concentrations in Skins and Pulp at Harvest

Girdling is a traditional horticultural practice applied at fruit set or other phenological stages, and is used mostly as a vine management. In grapevines, it is used primarily for table grapes to improve berry weight, sugar content, color, and to promote early harvest. The objective of this study was to evaluate the effect of trunk girdling applied at veraison, in 'Cabernet Sauvignon' wine grapes (Vitis vinifera L.), on agronomical and physiological parameters during vine development from the onset of ripening (veraison) to harvest, and additionally to quantify the effect of girdling on primary and secondary metabolism. Girdling was applied 146 days after pruning (dap) at veraison, when berry sampling for metabolomics and agronomical evaluations commenced, with a further three sampling dates until harvest, at 156 dap (30% maturation, 10 days after girdling-dag), 181 dap (70% maturation, 35 dag), and 223 dap (commercial harvest, 77 dag). Skin/pulp and seed tissues were extracted separately and metabolomics was performed using one-dimensional proton nuclear magnetic resonance (1D 1H NMR) spectroscopy and high performance liquid chromatography (HPLC-DAD). At harvest, girdling significantly increased stomatal conductance (gs) in vines, decreased glutamine concentrations, and increased anthocyanin and flavonol concentrations in the skin/pulp tissues of grape berries. Berry weight was reduced by 27% from 181 dap to harvest, and was significantly higher in grapes from girdled vines at 181 dap. Sugars, organic acids, and other amino acids in skin/pulp or seeds were not significantly different, possibly due to extra-fascicular phloem vessels transporting metabolites from leaves to the roots. Using a metabolomics approach, differences between skin/pulp and seeds tissues were meaningful, and a greater number of secondary metabolites in skin/pulp was affected by girdling than in seeds. Girdling is a simple technique that could easily be applied commercially on vine management to improve berry color and other phenolics in 'Cabernet Sauvignon' grapes.

Evolution of Volatile and Phenolic Compounds during Bottle Storage of Merlot Wines Vinified Using Pulsed Electric Fields-Treated Grapes

This study aimed to elucidate changes in volatile, phenolic, and oenological profiles of wines vinified from Pulsed Electric Fields (PEF)-treated and untreated Merlot grapes during bottle storage of up to 150, 90, and 56 days at 4 °C, 25 °C, and 45 °C, respectively, through chemometrics technique. Wines produced from untreated grapes and those PEF-treated at four different processing conditions (electric field strength 33.1 and 41.5 kV/cm and energy inputs between 16.5 and 49.4 kJ/kg) were used for the bottle storage study. Results showed that hydroxycinnamic and hydroxybenzoic acids in all stored wines, regardless vinified from untreated and PEF-treated grapes, increased as a function of time and temperature, while anthocyanins and selected esters (e.g., ethyl butanoate) decreased. Extreme storage temperature, at 45 °C particularly, resulted in a higher amount of linalool-3, 7-oxide in all stored wines. After prolonged storage, all wines produced from grapes PEF-treated with four different processing conditions were shown to favor high retention of phenolics after storage but induced faster reduction of anthocyanins when compared to wines produced from untreated grapes. Moreover, some volatiles in wines vinified using PEF-treated grapes, such as citronellol and 2-phenylethyl acetate, were found to be less susceptible towards degradation during prolonged storage. Production of furans was generally lower in most stored wines, particularly those produced from PEF-treated grapes at higher energy inputs (>47 kJ/kg). Overall, PEF pre-treatment on grapes may improve storage and temperature stability of the obtained wines.

Impact of closure type and storage temperature on chemical and sensory composition of Malbec wines (Mendoza, Argentina) during aging in bottle

Malbec is the flagship variety of Argentina mainly due to its high oenological value and plasticity to obtain different wine styles. During bottled aging, the chemical and organoleptic composition of wines is subject to changes depending on the aging conditions (closure, oxygen level, temperature, time). However, the combined effect of these factors on chemical composition and organoleptic characteristics of Malbec wines has not been studied yet. Wines were bottled with screw cap and natural cork and were kept in chambers at 15 °C and 25 °C for 2 years. Sampling was performed at 2, 4, 6, 9, 12, 15, 18, 21 and 24 months. Concentrations of free sulfur dioxide, dissolved oxygen, anthocyanins, tannins, esters, volatile phenols, organic acids, and color saturation decreased during the storage process. While, the formation of polymeric pigments, the color attributes (lightness and hue) and the levels of alcohols, norisoprenoids, furanoids and terpenoids increased. At 24 months, Malbec wines were organoleptically different. Wines kept at 15 °C were associated with high sensory perceptions in color intensity and violet tint, those presented a positive correlation with free sulfur dioxide, tannins, and anthocyanins levels. On the contrary, wines aged at 25 °C were linked with high sensory perceptions of dried vegetative and dried fruit aromas. These descriptors were positively correlated with norisoprenoids, furanoids, and terpenoids. In general, the chemical composition and organoleptic attributes of bottled Malbec wines (Mendoza, Argentina) were stable respect closure type employed, but highly sensitive to the combined effect of time and storage temperature. This finding is key to making decisions about the wine style searched, and costs (e.g. refrigeration) involved in the conservation period until consumption.