Compounds In Wine Research Articles

Validation Study on the Simultaneous Quantitation of Multiple Wine Aroma Compounds with Static Headspace-Gas Chromatography-Ion Mobility Spectrometry.

A new quantitative method based on static headspace-gas chromatography-ion mobility spectrometry (SHS-GC-IMS) is proposed, which enables the simultaneous quantitation of multiple aroma compounds in wine. The method was first evaluated for its stability and the necessity of using internal standards as a quality control measure. The two major hurdles in applying GC-IMS in quantitation studies, namely, nonlinearity and multiple ion species, were also investigated using the Boltzmann function and generalized additive model (GAM) as potential solutions. Metrics characterizing the model performance, including root mean squared error, bias, limit of detection, limit of quantitation, repeatability, reproducibility, and recovery, were investigated. Both nonlinear fitting methods, Boltzmann function and GAM, were able to return desirable analytical outcomes with an acceptable range of error. Potential pitfalls that would cause inaccurate quantitation, that is, effects of ethanol content and competitive ionization, were also discussed. The performance of the SHS-GC-IMS method was subsequently compared against that of a currently established method, namely, GC-MS, using commercial wine samples. These findings provide an initial validation of a GC-IMS-based quantitation method, as well as a starting point for further enhancing the analytical scope of GC-IMS.

Ozone and Bioactive Compounds in Grapes and Wine.

Ozone is widely used in the agri-food and food processing industries mainly as a sanitizing agent. However, it has recently become clear that ozone exposition leads to another important benefit: in living tissues, the induced-oxidative stress triggers the antioxidant response, and, therefore, it enhances the production of antioxidant and stress-related secondary metabolites. As such, ozone can be considered an abiotic elicitor. The goal of the present review was to critically summarize knowledge about the possibility of improving bioactive compounds and, consequently, the health-related properties of grapes and wine, by using ozone. The greatest interest has been given not only to the pre- and post-harvest treatment of table and wine grapes, but also to the explanation of the mechanisms involved in the ozone-related response and the main secondary metabolites biosynthetic pathways. From the literature available, it is clear that the effect of ozone treatment on health-related properties and secondary metabolites accumulation depends on many factors, such as the cultivar, but also the form (water or gaseous), doses, and application method of ozone. Most of the published papers report an increase in antioxidant compounds (e.g., polyphenols) and stress-related volatiles, confirming the hypothesis that ozone could be used to improve berry and wine compositional and sensory quality.

LC‐DAD‐ESI‐MS/MS characterization of phenolic compounds in wines fromVitis vinifera‘Shesh i bardhë’ and ‘Vlosh’ cultivars

Phenolic compounds in white wines produced by cv. Shesh i bardhë, and red wines produced by cv. Vlosh, two native grape cultivars of Albania, was investigated by using Liquid Chromatography-Diode Array Detection-Electrospray Ionization-Tandem Mass Spectrometry (LC-DAD-ESI-MS/MS). A total of 32 phenolic compounds including phenolic acids, flavan-3-ols, flavonols, and stilbenes were identified in both wines, with flavanols the main family contributing to total phenolics, from 45.3% to 89.9%. Gallic acid, procyanidin dimer, and trans-caftaric acid were found main compounds in both wines. Significant differences have been found depending on the region and vintage. It was observed that total phenolic content in wines from the Durrësi region stands higher compared to wines originating from the Tirana region. As a result, significant variations were found among the cultivars in terms of the phenolic profiles, and Shesh i bardhë wines phenolic compounds were much higher than the Vlosh wines. Novelty impact statement This is the first study on the phenolic compounds of the white wine from Shesh i bardhë grape cv. and red wine produced by Vlosh cv. in Albania. The presence of 30 phenolic compounds was identified through LC-DAD-ESI-MS/MS, with flavanols the main family contributing to total phenolics, from 45.3% to 89.9%. Gallic acid, procyanidin dimers, as well as resveratrol were found in both wines.

Natural Compound Resveratrol Attenuates TNF-Alpha-Induced Vascular Dysfunction in Mice and Human Endothelial Cells: The Involvement of the NF-κB Signaling Pathway.

Resveratrol, a natural compound in grapes and red wine, has drawn attention due to potential cardiovascular-related health benefits. However, its effect on vascular inflammation at physiologically achievable concentrations is largely unknown. In this study, resveratrol in concentrations as low as 1 μm suppressed TNF-α-induced monocyte adhesion to human EA.hy926 endothelial cells (ECs), a key event in the initiation and development of atherosclerosis. Low concentrations of resveratrol (0.25–2 μm) also significantly attenuated TNF-α-stimulated mRNA expressions of MCP-1/CCL2 and ICAM-1, which are vital mediators of EC-monocyte adhesion molecules and cytokines for cardiovascular plaque formation. Additionally, resveratrol diminished TNF-α-induced IκB-α degradation and subsequent nuclear translocation of NF-κB p65 in ECs. In the animal study, resveratrol supplementation in diet significantly diminished TNF-α-induced increases in circulating levels of adhesion molecules and cytokines, monocyte adhesion to mouse aortic ECs, F4/80-positive macrophages and VCAM-1 expression in mice aortas and restored the disruption in aortic elastin fiber caused by TNF-α treatment. The animal study also confirmed that resveratrol blocks the activation of NF-κB In Vivo. In conclusion, resveratrol at physiologically achievable concentrations displayed protective effects against TNF-α-induced vascular endothelial inflammation in vitro and In Vivo. The ability of resveratrol in reducing inflammation may be associated with its role as a down-regulator of the NF-κB pathway.

Maturation Process, Nutritional Profile, Bioactivities and Utilisation in Food Products of Red Pitaya Fruits: A Review

Red pitaya (Hylocereus polyrhizus, red pulp with pink peel), also known as dragon fruit, is a well-known species of pitaya fruit. Pitaya seeds and peels have been reported to exhibit higher concentrations of total polyphenols, beta-cyanins and amino acid than pulp, while anthocyanins (i.e., cyanidin 3-glucoside, delphinidin 3-glucoside and pelargonidin 3-glucoside) were only detected in the pulp extracts. Beta-cyanins, phenolics and flavonoids were found to increase gradually during fruit maturation and pigmentation appeared earlier in the pulp than peel. The phytochemicals were extracted and purified by various techniques and broadly used as natural, low-cost, and beneficial healthy compounds in foods, including bakery, wine, dairy, meat and confectionery products. These bioactive components also exhibit regulative influences on the human gut microbiota, glycaemic response, lipid accumulation, inflammation, growth of microbials and mutagenicity, but the mechanisms are yet to be understood. The objective of this study was to systematically summarise the effect of red pitaya’s maturation process on the nutritional profile and techno-functionality in a variety of food products. The findings of this review provide valuable suggestions for the red pitaya fruit processing industry, leading to novel formulations supported by molecular research.

Whole bunch fermentation and the use of grape stems: effect on phenolic and volatile aroma composition ofVitis viniferacv. Pinot Noir wine

Background and Aims Whole bunch fermentation is widely used in red wine production but research on whole bunch fermentation is limited, especially for cool climate Pinot Noir. Inclusion of whole bunches or grape stems was investigated in Pinot Noir wine production with respect to extraction of phenolic compounds and aroma production. Methods and Results Five Pinot Noir wines were microvinified by including grape stems or whole bunches at various levels: destemmed grapes (DS), 100% stems added back (DS100), 30% whole bunches (WB30), 60% whole bunches (WB60) and 100% whole bunches (WB100). The DS100, WB60 and WB100 treatments showed significantly increased tannin and monomeric phenolics but decreased anthocyanin in wines, which would consequently influence the mouthfeel and colour of wine. Volatile compounds responsible for green/vegetative, spicy, woody and medicinal aromas, including 3-isobutyl-2-methoxypyrazine, 3-isopropyl-2-methoxypyrazine, eugenol, ethyl cinnamate and phenol, were significantly increased in DS100, WB60 and WB100 treatments. The WB30 treatment did not show a significant increase of methoxypyrazines in the resultant wine. Conclusions By adding stems or a high proportion of whole bunches in fermentation, increased extraction of tannins may improve the mouthfeel and structure of Pinot Noir wine, but the significantly increased concentration of methoxypyrazines could negatively affect wine quality due to the enhanced green characteristics. Significance of the Study This study reveals the significant impact of stem inclusion during fermentation on phenolic and aroma compounds in Pinot Noir wine, which provides insights into better use of whole bunches and stems to improve Pinot Noir wine quality.

White wine protein instability: a review

The presence of protein compounds in wine leads to decreased organoleptic quality of finished products such as clarity and hue. These compounds have important nutritional values. A large part of the proteins present in wine are closely related to the pathogenesis process. Disturbance in wine samples occurs as a consequence of the presence of several non-protein factors such as the presence of phenolic compounds, metals and pH. To date, a wide range of procedures are known for the protein of wine precipitation in order to determine the total protein content of wine samples, using solutions such as: trichloroacetic acid (TCA), acetone, ethanol, etc. Numerous techniques specific to the process of protein stability are also known and developed. The best known techniques for determining protein stability are: thermal with the addition of chemicals, bentonite, tannin, ProtoCheck, acetone respectively combined (hot test + tannin, etc.).

Yeast Plasma Membrane Fungal Oligopeptide Transporters Display Distinct Substrate Preferences despite Their High Sequence Identity.

Fungal Oligopeptide Transporters (Fot) Fot1, Fot2 and Fot3 have been found in Saccharomyces cerevisiae wine strains, but not in strains from other environments. In the S. cerevisiae wine strain EC1118, Fot1 and Fot2 are responsible for a broader range of oligopeptide utilization in comparison with strains not containing any Fot. This leads to better fermentation efficiency and an increased production of desirable organoleptic compounds in wine. Despite the benefits associated with Fot activity in S. cerevisiae within the wine environment, little is known about this family of transporters in yeast. The presence of Fot1, Fot2 and Fot3 in S. cerevisiae wine strains is due to horizontal gene transfer from the yeast Torulaspora microellipsoides, which harbors Fot2Tm, FotX and FotY proteins. Sequence analyses revealed that Fot family members have a high sequence identity in these yeast species. In this work, we aimed to further characterize the different Fot family members in terms of subcellular localization, gene expression in enological fermentation and substrate specificity. Using CRISPR/Cas9, we constructed S. cerevisiae wine strains containing each different Fot as the sole oligopeptide transporter to analyze their oligopeptide preferences by phenotype microarrays. The results of oligopeptide consumption show that Fot counterparts have different di-/tripeptide specificities, suggesting that punctual sequence divergence between FOT genes can be crucial for substrate recognition, binding and transport activity. FOT gene expression levels in different S. cerevisiae wine strains during enological fermentation, together with predicted binding motifs for transcriptional regulators in nitrogen metabolism, indicate that these transporters may be under the control of the Nitrogen Catabolite Repression (NCR) system. Finally, we demonstrated that Fot1 is located in the yeast plasma membrane. This work contributes to a better understanding of this family of oligopeptide transporters, which have demonstrated a key role in the utilization of oligopeptides by S. cerevisiae in enological fermentation.

Phenolic contents, antioxidant activity and colour density of Slovak Pinot Noir wines

Recent studies show that wine contains more than thousand different compounds that could come from grapes, or could be formed in the process of winemaking and maturing. The most abundant compounds in wines are polyphenols, which affect sensory properties such as colour, taste and aroma, but also has antioxidant properties. The aim of this study was to determine total polyphenol and total anthocyanin contents, and to evaluate antioxidant effects and wine colour density of red wines ‘Pinot Noir’ produced in Slovakia. Thirteen analysed, bottled, quality dry ‘Pinot Noir’ wines with origin in various Slovak wine regions were purchased in retail network, to provide that analysed samples of wine would have the same properties as wines that are consumed by common consumers. The content of total polyphenols in analysed ‘Pinot Noir’ wines ranged from 1458 to 3324 mg GAE l-1, while contents of total anthocyanins ranged from 43.6 to 279.6 mg l-1. Antioxidant activities ranged from 80.2 % to 85.3 % inhibition of DPPH and wine colour density ranged from 0.679 to 1.495. The highest total polyphenol content, total anthocyanin content, and wine colour density was determined in wines from the south Slovakia winegrowing region, while the highest antioxidant activity in wines from Nitra winegrowing region. Results did not show significant differences among studied parameters in wines from different winegrowing regions. Results showed that Slovakian ‘Pinot Noir’ wines have characteristics comparable with ‘Pinot Noir’ wines from other countries.

Phytochemical content, and antioxidant activity, and volatile compounds associated with the aromatic property, of the vinegar produced from rosehip fruit (Rosa canina L.)

This study was aimed to be produced rosehip vinegar production from rosehip fruit, which has a limited usage, for the first time, and to monitor in detail the changes in bioactive compounds and volatile compounds, which affected on aroma property of it, during the rosehip vinegar production. Thus, it was aimed to contribute to the modernization of fermented foods and to produce rosehip vinegar as a healthy, aromatic and alternative product. The results showed that the rosehip vinegar had high TPC, TFC contents, and antioxidant activity. And catechin, ellagic-acid, quercetin, taxifolin, 4-hydroxy-benzoic-acid, and salicylic-acid were the important phenolic compounds in the rosehip wine and vinegar. Besides, vitamin-C content increased during the fermentation, and the highest value of vitamin-C was obtained in the rosehip vinegar. And, in the vinegar, it was displayed a total of 27 volatile compounds, the major compounds were acetic-acid, acetoin, pentanoic-acid, propionic-acid, octanoic-acid, followed by vitispirane, phenethyl-alcohol, isobutyric-acid, and 1-p-menthen-9-al. As a result, it has been thought that the rosehip fruit an adequate substrate for the production of rosehip vinegar which is a healthy and aromatic vinegar. Also, rosehip vinegar, obtained from rosehip fruit, which has a limited usage was contributed to the modernization of fermented foods.

Evaluation of antioxidant, organic acid, and volatile compounds in coffee pulp wine fermented with native yeasts isolated from coffee cherries.

In this study, coffee pulp was examined as a starting material to make alcoholic beverages (coffee pulp wine) and yeast fermentation ability. We have evaluated five yeasts, three of which were previously isolated from the coffee cherry, and the other two were commercial yeasts. The pH, °Brix, viable yeast cells, and color parameters of coffee pulp wines were measured. The antioxidant activity of coffee pulp wine were measured using the 2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant power assays. Relatively, the 2,2-diphenyl-1-picrylhydrazyl inhibition percentage of Saccharomycopsis fibuligera (strain KNU18Y4) fermented coffee pulp wine was higher than that of other yeasts. Coffee pulp wine fermented with Saccharomyces cerevisiae (strain Fermivin) had higher ferric reducing antioxidant power values. Coffee pulp wine fermented with S. fibuligera (strain KNU18Y4) produced higher total phenolic content and total flavonoid content. Coffee pulp wine fermented with S. cerevisiae (strain KNU18Y12) had lower total tannin content compared to other treatments. The citric and malic acid contents were higher in coffee pulp wine fermented with S. cerevisiae (strain Fermivin). On the other hand, high lactic and acetic acid produced, with coffee pulp wine fermented with S. fibuligera (strain KNU18Y4). Ethyl alcohol was the most abundant volatile compound found in all treatments.

Wine Oligosaccharides: Underutilized or Irrelevant? A Study into the Effects of Oligosaccharides on Wine Taste and Mouthfeel

The taste and mouthfeel of a wine are two of the most important aspects of wine tasting. However, while much is known about phenolic compounds and other macromolecules direct effects on wine taste and mouthfeel, little is known about other wine compounds such as oligosaccharides. This experiment uses Fructo-oligosaccharide (FOS) and Galacto-oligosaccharide (GOS) at two different concentrations, 450 mg/L and 900 mg/L within a simple model wine matrix. A model matrix was used to control for any unknown interactions between oligosaccharides and the multitude of wine components. Oligosaccharides were added individually to the model wine matrix at each concentration to create four treatments. Triangle tests were performed on all treatments against the control base model wine and between the high and low concentrations of each oligosaccharide treatment. Following the triangle tests, each treatment and the control underwent descriptive analysis (DA) using line intensity scales for sweetness, bitterness, astringency, acidity, and viscosity. Triangle test results revealed a significant difference only between the FOS450 and FOS900 samples. The wine matrix was made more complicated by adding polyphenols and still, none of the four oligosaccharide treatment groups were found to be significantly different. DA found no significant differences for the five attributes but did show clear trends in increased sweetness and acidity, decreased bitterness, as well as changes to astringency and viscosity. This suggests there may be more complex interactions happening within the mouth. However, given the lack of significant results in the simple wine model and the more complex wine model wine, any complex interactions between oligosaccharides and other wine compounds are likely to be minimal.

Effect of Different Winemaking Conditions on Organic Acids Compounds of White Wines.

Organic acids represent naturally occurring compounds that are found in many types of food and beverages, with important functions in defining products’ final quality. Their proportions in wine are dependent on grape composition and winemaking conditions (temperature, pH levels, oxygen, and carbon dioxide concentration). Therefore, this article studied the influence of different fermentation conditions (200 hL tanks vs. 50 L glass demijohns) and various yeasts on the evolution of the main organic acids during alcoholic fermentation of “Aligoté” wines. The fermentation lasted 22 days and samples were collected daily. Laboratory analyses were quantified according to the International Organization of Vine and Wine recommendations. High-performance liquid chromatography for the identification and quantification of organic acids was used. The data showed the important effect of winemaking conditions on sugar consumption, density or acidity values, and sensory characteristics. Significant differences in organic acid concentrations (especially for tartaric acid) were obtained for all variants, depending on the fermentation conditions, inoculated yeast and the sampling moment. The quantities of most of the identified organic acids were generally significantly increased when glass vessels were used, compared to those fermented in tanks. Most organic acids concentrations were favored by lower pH and showed higher values at lower temperatures.

The effect of grape juice dilution and complex nutrient addition on oenological fermentation and wine chemical composition

The impact of water addition and complex nutrient addition to grape juice in laboratory scale winemaking, on both alcoholic and malolactic fermentation duration and outcome has been examined using commercial wine yeasts, Lalvin EC1118™ and Lalvin R2™and malolactic bacteria Lalvin VP41™. As expected, dilution with water did not impede fermentation, instead resulted in shortened duration, or in the case of malolactic fermentation enabled completion in these conditions. Addition of complex organic nutrient further shortened alcoholic fermentation by Lalvin R2™ and in some conditions also reduced the duration of malolactic fermentation. In general, compounds contributing to wine aroma and flavour were present at lower concentrations at the end of fermentation where juices were diluted and the addition of organic complex nutrient also influenced the concentration of some compounds in wine. These findings are significant to commercial winemaking, highlighting that winemakers should consider potential impacts of juice dilution on processing efficiencies along with wine flavour and aroma.

Degradation of cyanidin-3-O-glucoside induced by antioxidant compounds in model Chinese bayberry wine: Kinetic studies and mechanisms

The degradation kinetic of cyanidin-3-O-glucoside was determined in combination with different antioxidants, namely ascorbic acid, cysteine, reduced glutathione, and sodium sulfite at different concentrations and temperatures (4, 20, and 37 °C) in model Chinese bayberry wine. Ascorbic acid, cysteine, and reduced glutathione accelerated cyanidin-3-O-glucoside degradation; half-life times decreased by ca. 46 ∼ 93%, 0.39 ∼ 88%, and 1.6 ∼ 92% respectively when the concentrations of antioxidants were 0.1 ∼ 5 mM. Thiols with more -SH groups lead to faster degradation of cyanidin-3-O-glucoside. Interactions of oxidized cyanidin-3-O-glucoside with antioxidants were evaluated in aqueous solution and methanol to investigate the degradation mechanism of anthocyanin after oxidation. An anthocyanin-cysteine adduct was identified by LC-MS and formation pathways are proposed, along with mechanisms of anthocyanin degradation induced by antioxidants.

Analysis of aroma and polyphenolic compounds in Saperavi red wine vinified in Qvevri.

The purpose of this study is to analyze and characterize a Georgian red wine from Saperavi grape, obtained in Qvevri (Georgian traditional winemaking method), by using innovative techniques for the determination of the polyphenolic content, aroma, and its correlation to the sensory characteristics. This peculiar red wine, after high‐performance liquid chromatography with diode‐array detection and mass spectrometry (HPLC‐DAD‐MS), headspace solid‐phase microextraction–gas chromatography–mass spectrometry (HS‐SPME‐GC‐MS), and HS‐SPME‐GCxGC‐MS/TOF (two‐dimensional gas chromatography) chemical characterization showed a high polyphenol content (19.6 × 102 mg/L, 38.4% anthocyanins) and a wide range of volatile compounds, among which terpenes were associated with the aroma of flowers, lemongrass, and wood. Analyses were also conducted to determine the total polyphenol content correlated to antioxidant activity with the Folin–Ciocalteu spectrophotometric in vitro method (4.650 g GAE/L). In conclusion, for the first time on Saperavi wine, innovative techniques such as HPLC‐DAD‐MS, GC‐MS, and GCxGC‐MS/TOF were simultaneously applied in association with the traditional analytic techniques to perform a complete chemical characterization. These activities are part of a project about circular viticulture in the Georgian territory that will lead the production of traced quality wines and the valorization of the Georgian wine sector.

Effects of Wine Components in Inflammatory Bowel Diseases.

With the rising prevalence of Inflammatory bowel disease (IBD) worldwide, and the rising cost of treatment with novel biological drugs, there is an increasing interest in various diets and natural foods as a potential way to control/modulate IBD. As recent data indicates that diet can modify the metabolic responses essential for the resolution of inflammation, and as wine compounds have been shown to provide substantial anti-inflammatory effect, in this review we aimed to discuss the current evidence concerning the impact of biological compounds present in wine on IBD. A number of preclinical studies brought forth strong evidence on the mechanisms by which molecules in wine, such as resveratrol or piceatannol, provide their anti-inflammatory, anti-oxidative, anti-tumor, and microbiota-modulation effects. However, concerning the effects of alcohol, it is still unclear how the amount of ethanol ingested within the framework of moderate wine consumption (1–2 glasses a day) affects patients with IBD, as human studies regarding the effects of wine on patients with IBD are scarce. Nevertheless, available evidence justifies the conductance of large-scale RCT trials on human subjects that will finally elucidate whether wine can offer real benefits to the IBD population.

Influence of tannins, human saliva, and the interaction between them on volatility of aroma compounds in a model wine.

During wine drinking, aroma release is mainly impacted by wine matrix compositions and oral physiological parameters. Notably, tannins in wine could interact with saliva protein to form aggregates which might also affect the volatility of volatiles. To explore tannins, saliva, and the interaction between them on the volatility of volatiles, the volatility of 16 aroma compounds in the model wine mixed with the commercial tannin extracts, human saliva, or both respectively, was evaluated in vitro static condition by using HS-SPME-GC/MS. The volatility of aroma compounds with high hydrophobicity or benzene ring appeared to decrease more when increasing the tannin levels. Specifically, the volatility of ethyl octanoate, β-ionone, and guaiacol was decreased more than 20% by adding 2 g/L tannin extract. The addition of human saliva could significantly inhibit volatility of most aroma compounds in the model wine. Furthermore, the volatility of most aroma compounds in the mixture of tannins and human saliva was significantly lower than the control or the sample which were added with tannins or human saliva individually. The volatility of some aroma compounds in the mixture of the tannin and saliva was only around 50% or less, relative to the control. Two-way ANOVA analysis showed that there was a synergistic effect between tannin and saliva on decreasing the volatility of most aroma compounds (p < 0.05). Overall, understanding the effect of key factors such as tannins and saliva on volatility of volatiles could help to understand the sophisticated retronasal perceptions during wine tasting. PRACTICAL APPLICATION: The outputs of this research will be helpful in understanding the impact of tannins on retronasal aroma release during wine tasting. It might promote the control of tannins in the viticulture and brewing process to improve the retronasal perception of wine aroma.

Adaptation of an olfactometric system in a GC-FID in combination with GCxGC/MS to evaluate odor-active compounds of wine

A step-by-step approach to easily adapt and use a GC-FID as an olfactometer, as well as a detailed description of acquisition and interpretation of olfactometric data by the OSME (from the Greek word for odor, ὀσμή) method. A Merlot wine was used to exemplifly this strategy and its volatiles were characterized, rendering 43 volatiles in 1D-GC/MS and 142 in GCxGC/MS. GC-O showed the presence of 24 odor-active compounds and GCxGC/MS indicated aditional 14 odor-active compounds, which were found as coelutions. Six compounds (isoamyl acetate, ethyl octanoate, ethyl decanoate, 3-methylthio-1-propanol, carvone, benzyl alcohol and nonanoic acid) were described in 1D-GC-O analyses as having distinct odors by the same and by different assessors. This fact indicated the presence of coeluting bands, which were resolved by GCxGC/MS. The adapted GC-O in combination with the use of GCxGC/MS may be a tool to more accurate investigation of the odor-active compounds of wine.

Development of a new procedure for the determination of the reactivity of brandies used in wine fortification

The main purpose of this work was to describe and validate a new methodology for the determination of a brandy reactivity index (BRI) towards flavan-3-ol compounds in wines (catechins and condensed tannins) and to correlate this index with the amount and type of aldehydes present in those brandies. This new method consists of two main reactions: a) the ability of aldehydes to react with C8 and/or C6 positions in the phloroglucinol ring of a catechin present in excess (A ring); b) further reaction of the remaining free catechin with p-dimethylaminocinamaldehyde (DMACA) yielding to the formation of a blue compound that can be quantified by Visible spectroscopy at 640 nm. The impact of different experimental conditions such as reagent concentrations and reaction time on BRI were also evaluated. The method was validated through the determination of repeatability (intra-day variability) and reproducibility. The repeatability was considered acceptable with a CV of 11.87 %. The analysis of the reproducibility variance, S2R (11.59), the reproducibility limit R (9.5) and the reproducibility coefficient of variation, CVR (15.25 %) postulates BRI methodology to be reliable and robust.Using the developed methodology, the BRI of fourteen different commercial brandies and some pure standards aldehydes were determined. The aldehydes present in brandies, and the content of total aldehydes were determined by GC-MS and then correlated with the BRI. In general, it was observed a direct correlation between the BRI and the concentration of total aldehydes, in particular acetaldehyde.