Headspace solid‐phase micro extraction coupled to comprehensive two‐dimensional with time‐of‐flight mass spectrometry applied to the evaluation of Nebbiolo‐based wine volatile aroma during ageing

This study presents the application of a headspace solid‐phase microextraction (HS‐SPME) method on the analysis of Nebbiolo‐based wine volatiles by comprehensive two‐dimensional gas chromatography (GC×GC) and time‐of‐flight mass spectrometry (TOF‐MS). The aroma patterns were established for different samples of Nebbiolo‐based wines, aged in oak wood barrels for 18 months at constant temperature. The methodology allowed for the simultaneous analysis of over 130 different volatile compounds detected in the headspace. The odour activity values (OAVs) were assessed to identify potentially important odorants of Nebbiolo‐based wine during ageing. The highest OAVs were obtained for several compounds such as ethyl octanoate, ethyl hexanoate, isoamyl acetate, β‐damascenone, ethyl cinnamate, ethyl 3‐methylbutanate and acetaldehyde. Ethyl butanoate, octanoic acid, ethyl dihydrocinnamate and γ‐nonalactone were also at concentrations higher than their corresponding threshold. Also vanillin, (E)‐whisky lactone, (Z)‐whisky lactone, guaiacol and 4‐ethyl guaiacol seem to be important odorants after oak wood ageing period.     

A kinetic study of the reactions of (+)‐catechin with aldehydes derived from toasted oak

The reactions between (+)‐catechin and representative oak wood furanic (furfuraldehyde, 5‐hydroxymethylfurfuraldehyde and 5‐methylfurfuraldehyde) and phenolic (vanillin and syringaldehyde) aldehydes in a wine‐like model solution were studied and the corresponding condensation kinetics at pH 3.0 and 3.5 were compared. A comparative study on the reactivity of these two representative families of aldehydes towards (+)‐catechin showed a large difference between them. When incubated separately with (+)‐catechin at both pH values, the reactions were faster with furanic aldehydes than with phenolic aldehydes. In mixtures containing (+)‐catechin and individual aldehydes, new compounds were identified by high‐performance liquid chromatography (HPLC)/UV–visible detection, some of which were characterised by liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI‐MS). The increase in solution absorbance with time was closely linked to these new products. Copyright © 2007 Society of Chemical Industry     

Mass spectrometry fragmentation pattern of coloured flavanol‐anthocyanin and anthocyanin‐flavanol derivatives in aged red wines of Rioja

Background and Aims: During wine ageing, a great variety of reactions take place, resulting in an immense variety of products whose structure sometimes remains unknown. The aim of this work is the study of different fragmentation patterns of flavanol‐anthocyanin derivatives formed along the wine ageing; these patterns are useful for elucidating the different structures of these compounds and other new related ones. Methods and Results: Several wines from the Protected Denomination of Origin Rioja have been studied by an analytical method that combines column chromatography and high‐performance liquid chromatography with diode array and mass and tandem mass spectrometric detections. Thirty‐five coloured flavanol‐anthocyanin compounds formed by direct reaction or by acetaldehyde‐mediated condensation have been identified. For direct reaction derivatives, two different fragmentation patterns (one of them not previously reported) have been observed depending on the position of flavanol in the coloured derivative. Several compounds have been identified in aged wines for the first time to the authors' knowledge, like (+)‐gallocatechin‐cyanidin‐3‐glucoside and (+)‐catechin‐cyanidin‐3‐glucoside Conclusions: The developed analytical procedure has allowed the identification of some compounds for the first time, and two different fragmentation patterns have been observed depending on the position of flavanol in the pigment. Significance of the Study: The establishment of different fragmentation patterns allows the structural elucidation of unknown compounds.     

Effect of sugar acylation on the antioxidant properties of Vitis vinifera red grape malvidin‐3‐glucoside

This work aims at studying the influence of sugar acylation on the antioxidant properties of Vitis vinifera red grape malvidin‐3‐glucoside. The antioxidant properties of malvidin‐3‐glucoside, malvidin‐3‐acetylglucoside, malvidin‐3‐coumaroylglucoside and malvidin‐3‐caffeoylglucoside were measured using different techniques. Their antiradical and reducing properties were determined using the DPPH and FRAP method, respectively. Malvidin‐3‐caffeoylglucoside displayed a DPPH value (20.2 μm Trolox eq.) much higher than malvidin‐3‐glucoside (13.6 μm Trolox eq.), but no significant differences were observed from the FRAP assay. Furthermore, the ability of these compounds to inhibit lipid peroxidation in a liposome membrane system was examined by monitoring oxygen consumption and the formation of conjugated dienes. Both assays allowed concluding that malvidin‐3‐caffeoylglucoside and malvidin‐3‐coumaroylglucoside inhibit lipid peroxidation significantly more than malvidin‐3‐glucoside. Altogether, the results reported herein indicate that acylation of malvidin‐3‐glucoside with phenolic acids like caffeic or coumaric acids, but not acetic acid, increases their overall antioxidant properties.     

Binding of oak volatile compounds by wine lees during simulation of wine ageing

The retention of wine volatile compounds by wine lees could have an influence on the quality of the product. The aim of this work was to study the binding of wine volatile compounds from oak wood by the wine lees during simulation of wine ageing. The compounds with the most affinity for the lees were eugenol, 4-propylguaiacol, 4-methylguaiacol, furfural and 5-methylfurfural. Lees also bound other compounds important for aroma in aged wine such as oak lactones, although to a lesser degree. Guaiacol and γ-nonalactone were the only compounds studied that were not bound by the lees. Because the lees bind important compounds to wine aroma, ageing red wine in oak barrel in presence of lees could diminish the impact of the aromatic compounds from oak wood on wine aroma.     

Extraction/oxidation kinetics of low molecular weight compounds in wine brandy resulting from different ageing technologies

This study provides innovative information on the influence of new technologies of ageing (stainless steel tanks with wood staves or wood tablets of chestnut or Limousin oak), in comparison with traditional technology (oak wooden barrels), on the extraction/oxidation kinetics of low molecular weight compounds of wine brandy. The brandy was sampled and analysed by HPLC during the first year of ageing. The results show that most of the compounds tend to increase over the time, but their extraction/oxidation kinetics depend on the ageing technology. The wooden barrels promote greater enrichment in the majority of the compounds. However, gallic acid, ellagic acid and syringaldehyde, and vanillin and 5-methylfurfural, which are strong antioxidants and key-odourant compounds, respectively, present higher contents in the brandy aged with the alternative technologies. Chestnut proves to be a suitable alternative to Limousin oak for the ageing of brandy in all the studied technologies, inducing faster evolution and high quality.     

First confirmation in red wine of products resulting from direct anthocyanin–tannin reactions

Analysis of wine fractions before and after thiolysis confirmed the occurrence in red wine of direct reactions between anthocyanins and tannins established earlier in model solutions. Results showed the presence of two types of structures differing in the linkage position of the anthocyanin moiety. On one hand, detection of malvidin‐3‐glucoside (Mv3g) among thiolysis products revealed the presence of anthocyanin‐derived pigments in which Mv3g is linked by its C‐6 or C‐8 top. On the other hand, LC/MS analysis allowed the detection of two derivatives tentatively identified as flavenes or a bicyclic condensation products yielded by the reaction of a flavanol monomer (C‐6 or C‐8 top) with malvidin‐3‐glucoside (C‐4 position). The presence of the corresponding benzylthioethers after thiolysis of the polymeric fractions confirmed that procyanidins are similarly involved in the latter reaction. Besides, MS also allowed the detection of new benzylthioethers of catechin derivatives released after thiolysis of the wine fractions, indicating that in addition to the postulated processes other types of reactions take place in wines. © 2000 Society of Chemical Industry     

Interaction of Œnococcus œni and oak wood compounds

The purpose of this work was to study the effect of wood extract on Œnococcus œni growth in synthetic media and its influence on the concentration of volatile compounds when lactic acid bacteria (LAB) are present. Analytical results and sensorial consequences are described when malolactic fermentation was performed in tank or barrels. Using gas chromatography-mass spectrometry, the modifications in oaklactone, eugenol, isoeugenol and vanillin levels were monitored in the presence of Œ. œni. These volatile compounds are known to have powerful characteristic odors (woody, spicy, smoky and vanillin) and to play a role in wine aroma. LAB cultures were performed in synthetic media supplemented with oak wood shavings or extracts. The bacterial growth rate was lower in the absence of heated shavings.This study shows that LAB, especially Œ. œni, are able to interact with wood and form volatile compounds. In laboratory medium, the heating of wood favored bacterial viability more than the simple addition of wood shavings. This is the first demonstration of the capacity of wine Œ. œni to enhance volatile compounds from wood.     

Inhibition ofIn VitroHuman LDL Oxidation by Phenolic Antioxidants from Grapes and Wines

Current research suggests that wine contains substances that may reduce the mortality rate from coronary diseases. The oxidation of low-density lipoprotein (LDL) is thought to be a key step in the development of atherosclerosis. Phenolic fractions of a Petite Syrah wine were evaluated for their antioxidant activity in inhibiting LDL oxidation in vitro . The more active fractions contained components of the catechin family. The catechin oligomers and the procyanidin dimers (B₂, B₃, B₄, B₆, B₈) and trimers (C₁, C₂) were extracted, isolated and purified from grapes seeds. These compounds were tested for their inhibition of LDL oxidation, along with other monomeric wine phenolics. The procyanidin dimers B₂ and B₈, and trimer C₁, and the monomers catechin, epicatechin and myricetin had the highest antioxidant activity. The procyanidin dimers B₃, B₄ and C₂ and the monomers gallic acid, quercetin, caffeic acid, and rutin, and a group of compounds that included the dimer B₆, ellagic acid, sinapic acid, cyanidin had lower antioxidant activity and α-tocopherol had the least activity. Thus, the numerous phenolic compounds found in wine are potent antioxidants in inhibiting LDL oxidation in vitro .     

Examination of the sulfur dioxide–ascorbic acid anti‐oxidant system in a model white wine matrix

The effectiveness of sulfur dioxide in inhibiting the ascorbic acid induced oxidation of (+)‐catechin in a matrix simulating white wine was investigated. At a sulfur dioxide:ascorbic acid mole ratio of 0.8:1.0, sulfur dioxide extended the delay prior to the onset of (+)‐catechin browning as measured by the increase in absorbance at 440 nm from 2 to 4 days post reaction initiation. The lengthening of the pre‐browning period was correlated with an increase in the time required to oxidise ascorbic acid completely, the sequence of events being loss of sulfur dioxide (day 3), loss of ascorbic acid (day 4) and on‐set of (+)‐catechin browning (day 4). Increasing the sulfur dioxide to ascorbic acid mole ratio to 3.0:1.0 inhibited the onset of (+)‐catechin browning over the 14‐day reaction period. This inhibition was achieved at considerable cost to the sulfur dioxide concentration, with the ratio of sulfur dioxide consumed to ascorbic acid oxidised being 1.7 compared with the expected fraction of 1.0. Reasons for the enhanced consumption of sulfur dioxide and the implications of this study for maintenance of quality in white wine production are discussed. Copyright © 2004 Society of Chemical Industry     

Chemical and chromatic characteristics of Tempranillo,Cabernet Sauvignon and Merlot wines from DO Navarra aged in Spanish and French oak barrels

The oenological quality of Spanish oak wood from Navarra (Quercus petraea Liebl.) in relation to French wood of recognised quality in cooperage has been evaluated. We have studied the effects of the Spanish wood on wine evolution during ageing, in regards to chromatic characteristics, polyphenols, and volatile compounds related to oak wood, in three different mono-varietal wines (cv. Tempranillo, cv. Cabernet Sauvignon and cv. Merlot) from the Origin Denomination Navarra. The results were compared with those obtained for the same wines aged in French oak barrels from central regions of France, obtained from five different French and Spanish cooperages.     

Interaction of (+)‐catechin, (−)‐epicatechin,procyanidin B2 and procyanidin C1 with pooled human saliva in vitro

Pooled human saliva was mixed with solutions containing either (+)‐catechin, (−)‐epicatechin, procyanidin B2 or procyanidin C1 at two ratios of admixture and allowed to react at pH 3.2. Precipitates were removed by centrifugation and the supernatants were analysed for the content of proteins and flavanols remaining. The protein determination was unexpectedly difficult and limited the amount of data obtained. The extent to which particular proteins were precipitated (as judged by reversed phase HPLC) did not correlate with the reported sensory potency of these flavanols. The quantity of flavanols precipitated not only did not agree with the relative astringency recorded in the literature, but was in fact the reverse. However, statistical analysis of the data suggested that the quantity of flavanols remaining in the supernatant might be more closely related to their previously determined astringency than to the amount precipitated. More extensive studies, both sensory and analytical, with a greater number of purified flavanols and a superior method of protein determination are required in order to confirm and refine the relationships suggested. © 2000 Society of Chemical Industry     

A study of the antioxidant capacity of oak wood used in wine ageing and the correlation with polyphenol composition

The antioxidant capacity of oak wood used in the ageing of wine was studied by four different methods: measurement of scavenging capacity against a given radical (ABTS, DPPH), oxygen radical absorbance capacity (ORAC) and the ferric reducing antioxidant power (FRAP). Although the four methods tested gave comparable results for the antioxidant capacity measured in oak wood extracts, the ORAC method gave results with some differences compared to the other methods. Non-toasted oak wood samples displayed more antioxidant power than toasted ones due to differences in the polyphenol composition. A correlation analysis revealed that ellagitannins were the compounds mainly responsible for the antioxidant capacity of oak wood. Some phenolic acids, mainly gallic acid, also showed a significant correlation with antioxidant capacity.     

Statistical differentiation of wines of different geographic origin and aged in barrel according to some volatile components and ethylphenols

The purpose of this paper was to study the effect of wine composition and geographical origin on the accumulation of volatile compounds in barrel-aged wines. Therefore, 267 wines belonging to different origin appellations were analysed. In order to analyse the data, a multivariate statistical technique was applied, that can be quite useful in creating an overall view of the problem in which multiple variables are analysed. Statistical analysis gave four significant factors, accounting for 84.12% of the variance. These factors summarise the information of a group of variables closely correlated to each other. Factor 1 grouped together oak lactones and eugenol, so it was associated with oak barrel type and with toasting of barrels. Factor 2 was associated with ethylphenols, related to wine quality diminution. Factor 3 grouped together guaiacol, furfural, and 5-methylfurfural, and was thus associated with wood thermal degradation; factor 4 was associated with the cis/trans ratio, related to oak origin. Whereas geographical origin of wines affected the accumulation of volatile compounds, the cis/trans ratio was only affected by oak barrel type. Among the tested parameters, alcoholic degree was the enological parameter that had the greatest effect on the accumulation of volatile compounds in wines. Oak lactones were the compounds that were present in all wines, so they could be used as oak ageing indicators.     

Flavan‐3‐ol C‐glycosides – Preparation and model experiments mimicking their human intestinal transit

In order to study the human intestinal transit of flavan‐3‐ol C‐glycosides, several C‐glycosyl derivatives were prepared by non‐enzymatic reaction of (+)‐catechin with α‐D ‐glucose, α‐D ‐galactose and α‐D ‐rhamnose, respectively. In contrast to literature data, we propose that the reaction mechanism proceeds in analogy to the rearrangement of flavan‐3‐ols during epimerization under alkaline conditions. Four of the 12 synthesized flavan‐3‐ol C‐glycosides were incubated under aerobic conditions at 37°C using saliva (2 min) and simulated gastric juice (3 h). To simulate human intestine, the C‐glycosides were also incubated under anaerobic conditions at 37°C both in human ileostomy fluid (10 h) and colostomy fluid (24 h), respectively. The flavan‐3‐ol C‐glycosides under study, i.e. (+)‐epicatechin 8‐C‐β‐D ‐glucopyranoside (1a), (+)‐epicatechin 6‐C‐β‐D ‐glucopyranoside (1d), (+)‐catechin 6‐C‐β‐D ‐galactopyranoside (2b), (+)‐catechin 6‐C‐β‐D ‐rhamnopyranoside (3b) were analyzed in the incubation samples by HPLC‐DAD and HPLC‐DAD‐MS/MS. They were found to be stable in the course of incubation in saliva, simulated gastric juice and ileostomy fluid and underwent degradation in colostomy fluid. While the 6‐C‐β‐D ‐glucopyranoside 1d was completely metabolized between 2 and 4 h, decomposition of the 6‐C‐β‐D ‐galactopyranoside 2b reached only 16±2% within 4 h of incubation. Linear degradation rates of 1d and 2b in colostomy fluid differed significantly. As microbial metabolism of flavan‐3‐ols is known not to be influenced by the stereochemistry of the aglycon, varying degradation rates are ascribed to the effect of the sugar moiety. Based on these results we assume that flavan‐3‐ol C‐glycosides pass through the upper gastrointestinal tract (oral cavity, stomach and small intestine) unmodified and are then metabolized by the colonic microflora.     

Differentiation of Wines Treated with Wood Chips Based on Their Phenolic Content,Volatile Composition,and Sensory Parameters

The effects of both wood chips addition and contact time on phenolic content, volatile composition, color parameters, and organoleptic character of red wine made by a native Greek variety (Agiorgitiko) were evaluated. For this purpose, chips from American, French, Slavonia oak, and Acacia were added in the wine after fermentation. A mixture consisting of 50% French and 50% Americal oak chips was also evaluated. In an attempt to categorize wine samples, various chemical parameters of wines and sensory parameters were studied after 1, 2, and 3 mo of contact time with chips. The results showed that regardless of the type of wood chips added in the wines, it was possible to differentiate the samples according to the contact time based on their phenolic composition and color parameters. In addition, wood‐extracted volatile compounds seem to be the critical parameter that could separate the samples according to the wood type. The wines that were in contact with Acacia and Slavonia chips could be separated from the rest mainly due to their distinct sensory characters.     

Bitterness and astringency of flavan‐3‐ol monomers,dimers and trimers

Intensity of astringency and bitterness of seven flavonoid compounds was evaluated by a time‐intensity (TI) procedure. Eighteen trained judges rated intensity continuously from ingestion, through expectoration at 10 s until extinction of the sensation. The seven stimuli included two flavan‐3‐ol monomers, (+)‐catechin and (−)‐epicatechin, three dimers and two trimers synthesised from catechin or epicatechin by condensation with (+)‐dihydroquercitin. As the degree of polymerisation increased, maximum bitterness intensity (I_max) and total duration (T_tot) decreased whereas astringency I_max increased. The monomers were significantly higher in bitterness at I_max than the dimers, which were significantly higher than the trimers. Astringency I_max of the monomers was lower than the dimers or trimers, although no significant difference was found in T_tot among the polymer classes. The bond linking the monomeric units had an influence on both sensory properties. The catechin‐catechin dimer linked by a 4→6 bond was more bitter than both catechin‐(4→8)‐catechin and catechin‐(4→8)‐epicatechin. Astringency was affected by both the specific linkage and the identity of the monomeric units with the dimer, catechin‐(4→8)‐catechin, being lower in astringency than either catechin‐(4→6)‐catechin or catechin‐(4→8)‐epicatechin. © 1999 Society of Chemical Industry     

Characterization of Date (Deglet Nour) Seed Free and Bound Polyphenols by High‐Performance Liquid Chromatography‐Mass Spectrometry

Date (Pheonix dactylifera L.) seeds are a valuable and abundant by‐product with various potential food applications. Free polyphenols (FPPs) and bound polyphenols (BPPs) of date seeds from Deglet Nour variety grown in Australia were investigated using high‐performance liquid chromatography‐mass spectrometry. The FPP fraction contained the following main phenolic compounds per gram of date seed powder; procyanidin B1 (499.8 ± 7.8 μg), procyanidin B2 (288.6 ± 6.1 μg), catechin (167.6 ± 2.1 μg), epicatechin (39.44 ± 0.39 μg), and protocatechuic acid (1.77 ± 0.22 μg). Additionally, one of the 2 A‐type dimers was confirmed as procyanidin A2 (24.05 ± 0.12 μg/g). A‐type dimers have not been reported before in date seeds. The BPP fraction contained epicatechin (52.59 ± 0.76 μg/g) and procyanidin B2 (294.2 ± 3.7 μg/g), while several peaks exhibiting ESI^? m/z of 153 indicated dihydroxybenzoic acid isomers including protocatechuic acid (2.138 ± 0.025 μg/g). These findings contributed to our knowledge of date seed phytochemicals and understanding of their contribution to the reported bioactivities.     

Phenolic compounds in a Spanish red wine aged in barrels made of Spanish,French and American oak wood

A red Rioja wine was aged in barrels made of Spanish oak wood for 21 months. The evolutions of colour percentage intensity, families of phenolic compounds and low molecular weight phenolic compounds were studied in these wines and compared with those of the same wine aged in barrels made of French and American oak. The analysis of chromatic parameters and total anthocyanins indicates that the wines aged in Spanish and French oak wood barrels have similar chromatic characteristics, but are significantly different to those of wines aged in barrels made of American oak wood, indicating a different degree of modification of the colour. The ageing process also had an important influence on the low molecular weight polyphenols composition of wine. The evolution of these components allowed the production of wines with different characteristics, in relation to the type of wood used in barrel making process. On the other hand, Spanish oak wood can be considered suitable for barrel production for quality wines, since a wine aged in barrels made of Spanish oak wood showed similar and intermediate characteristics to those of the same wine aged in French and American oak woods.