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Analytica Chimica Acta (v.660, #1-2)

Editorial Board (pp. iii).

Preview for Special Edition of Analytica Chimica Acta by Chantal Maury Chair, Organising Committee (pp. 1-1).

Examination of the potential for using chemical analysis as a surrogate for sensory analysis by John Blackman; Douglas N. Rutledge; Dejan Tesic; Anthony Saliba; Geoffrey R. Scollary (pp. 2-7).

The application of a multi-block statistical analysis method, known as Common Components and Specific Weight Analysis, to the determination of connections between sensory descriptors and analytical data for Hunter Valley Semillon is described. Sixteen wines were used in the data analysis with 15 sensory descriptors and 10 analytical measurements available for each wine. The multi-block analysis simplifies the comparison between the data sets and allows relationships between the sensory and analytical parameters to be readily ascertained, more effectively than a linear regression approach. A sweetness zone established the connections between several sensory descriptors and analytical measurements based on fructose. Glucose was not part of the sweetness connections, although glycerol was connected to the sensory sweetness descriptors. Sensory assessment of acidity was positively related to the titratable acidity and pH was negatively related. The malic acid concentration was also negatively related to sensory acidity and the possible reasons for this are described. Several sensory descriptors including toast, honey and kerosene were found to be in opposition to the sweetness sensory parameters and not connected to any analytical parameters. The outcomes of this multi-block treatment indicate the potential for using analytical measurements as a surrogate for sensory analysis.

Keywords: Sensory analysis; Chemical analysis; Chemometrics; Wine; Hunter Valley Semillon

Analysis and assessment of Madeira wine ageing over an extended time period through GC–MS and chemometric analysis by Ana C. Pereira; Marco S. Reis; Pedro M. Saraiva; José C. Marques (pp. 8-21).

Wine is one of the world's higher value agricultural products. The present work is centred on Madeira wine, a fine and prestigious example among Portuguese liqueur wines,with the main goal to deepen our understanding of relevant phenomena going on during the winemaking process, in particular during ageing of “Malmsey” Madeira wine.In this paper we present the results obtained from the chemical characterization of how its aroma composition evolves during ageing, and the development of a robust framework for analyzing the identity of aged Madeira wines. An extended ageing period was considered, covering a time frame of twenty years, from which several samples were analyzed in terms of their aromatic composition. The multivariate structure of this chemical information was then processed through multivariate statistical feature extraction techniques such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), in order to identify the relevant patterns corresponding to trends associated with wine ageing. Classification methodologies for age prediction were developed, using data from the lower dimensional sub-spaces obtained after projecting the original data to the latent variable spaces provided by PCA or PLS-DA. Finally, the performance for each classification methodology developed was evaluated according to their error rates using cross-validation methodologies (Leave-One-Out and k-fold Monte Carlo). Results obtained so far show that quite interesting classification performances can indeed be achieved, despite the natural variability present in wine products. These results also provide solid bases which can be used to build up available frameworks which assist quality monitoring and identity assurance tasks.

Keywords: Wine ageing; Multivariate analysis; Principal component analysis; Partial least squares discriminant analysis; Classification

Statistical correlation between flavanolic composition, colour and sensorial parameters in grape seed during ripening by Raúl Ferrer-Gallego; Matilde García-Marino; José Miguel Hernández-Hierro; Julián C. Rivas-Gonzalo; M. Teresa Escribano-Bailón (pp. 22-28).

The aim of this work has been to determine the correlations between sensory analysis, colour and content of main flavanols present in seeds. For this, the flavanic composition of grape seeds with different degrees of maturity was analysed by HPLC–DAD-MS and the obtained results were correlated with CIELab colour parameters, perceived colour (C), hardness of the seed (HS), tannic intensity (TI) and astringency (A). Multiple linear regression analysis (MLR) with the variables showing significant correlations ( p<0.05) was also performed. Grape seeds undergo important decreases in the content of catechins and procyanidin oligomers during ripening. Epicatechin-(4-8)-epicatechin-3-O-gallate (B2G) and (−)-epicatechin-3-O-gallate (ECG) are the flavanolic compounds whose contents decrease most. The changes in the phenolic composition accompany changes in TI, A and HS. The total content of flavanols in the seed is not the only factor affecting these attributes, since samples containing higher contents in flavanols can exhibit less astringency and tannic intensity than others with lower ones. The qualitative profile of the seeds is, therefore, also responsible for the sensations elicited in the mouth. A and HS parameters are more affected by the presence of galloylated dimeric procyanidins in the molecule than TI. CIELab colour parameters of seeds have high correlation coefficients with many flavanolic compounds. ECG was the compound most related to these parameters.

Keywords: Astringency; Tannic intensity; Proanthocyanidins; Ripening; Grape seeds

CO₂ volume fluxes outgassing from champagne glasses: The impact of champagne ageing by Gérard Liger-Belair; Sandra Villaume; Clara Cilindre; Philippe Jeandet (pp. 29-34).

It was demonstrated that CO₂ volume fluxes outgassing from a flute poured with a young champagne (elaborated in 2007) are much higher than those outgassing from the same flute poured with an older champagne (elaborated in the early 1990s). The difference in dissolved-CO₂ concentrations between the two types of champagne samples was found to be a crucial parameter responsible for differences in CO₂ volume fluxes outgassing from one champagne to another. Nevertheless, it was shown that, for a given identical dissolved-CO₂ concentration in both champagne types, the CO₂ volume flux outgassing from the flute poured with the old champagne is, in average, significantly lower than that outgassing from the flute poured with the young one. Therefore, CO₂ seems to “escape” more easily from the young champagne than from the older one. The diffusion coefficient of CO₂ in both champagne types was pointed as a key parameter to thoroughly determine in the future, in order to unravel our experimental observation.

Keywords: Champagne; Sparkling wines; Carbonated beverages; CO; ₂; Effervescence; Bubble nucleation; Champagne tasting

Sensory characteristics changes of red Grenache wines submitted to different oxygen exposures pre and post bottling by Soline Caillé; Alain Samson; Jérémie Wirth; Jean-Baptiste Diéval; Stéphane Vidal; Véronique Cheynier (pp. 35-42).

It is widely accepted that oxygen contributes to wine development by impacting its colour, aromatic bouquet, and mouth-feel properties. The wine industry can now also take advantage of engineered solutions to deliver known amounts of oxygen into bottles through the closures. This study was aimed at monitoring the influence of oxygen pick-up, before (micro-oxygenation, Mox) and after (nano-oxygenation) bottling, on wine sensory evolution. Red Grenache wines were prepared either by flash release (FR) or traditional soaking (Trad) and with or without Mox during elevage (FR+noMox, FR+Mox, Trad+noMox, Trad+Mox). The rate of nano oxygenation was controlled by combining consistent oxygen transfer rate (OTR) closures and different oxygen controlled storage conditions. Wine sensory characteristics were analyzed by sensory profile, at bottling (T0) and after 5 and 10 months of ageing, by a panel of trained judges. Effects of winemaking techniques and OTR were analyzed by multivariate analysis (principal component analysis and agglomerative hierarchical clustering) and analysis of variance. Results showed that, at bottling, Trad wines were perceived more animal and FR wines more bitter and astringent. Mox wines showed more orange shade. At 5 and 10 months, visual and olfactory differences were observed according to the OTR levels: modalities with higher oxygen ingress were darker and fruitier but also perceived significantly less animal than modalities with lower oxygen. Along the 10 months of ageing, the influence of OTR became more important as shown by increased significance levels of the observed differences. As the mouth-feel properties of the wines were mainly dictated by winemaking techniques, OTR had only little impact on “in mouth” attributes.

Keywords: Red wine; Winemaking techniques; Micro-oxygenation; Oxygen transfer rate; Synthetic closure; Sensory descriptive analysis

Sensory and chemical modifications of wine-brandy aged with chestnut and oak wood fragments in comparison to wooden barrels by Ilda Caldeira; Ofélia Anjos; Vera Portal; A.P. Belchior; Sara Canas (pp. 43-52).

Wooden barrels are used in the ageing or maturation of many alcoholic beverages, namely brandies and wines. However, the high costs related to ageing in wooden barrels have led to a search for alternative technologies. In this study we examined the application of wood fragments to the beverage in order to promote an accelerated ageing. We evaluated the sensory and chemical modifications in brandy aged in presence of two types of wood fragments, from two different woods (Limousin oak wood and Portuguese chestnut wood), and compared those with a brandy aged in wooden barrels.The results of the analysis of variance revealed more significant effects of wood botanical species than the ageing system on the sensory attributes. Concerning the ageing system, significant differences in brandy colour attributes were found, namely golden, topaz and greenish; olfactory attributes such as alcoholic, toasted and coffee; and the gustatory attribute, bitter. The brandies aged in the presence of wood tablets presented the highest intensities of topaz and greenish colour, toasted and coffee odours, while the brandies aged in wooden barrels presented the highest intensities of golden colour, alcohol odour and bitter taste. However, the overall quality of the brandies was similar.The analysis of odourant compounds showed a great discrimination of the brandies based on the ageing system. The brandies aged in wooden barrels presented the highest levels of several ethyl esters, acids, furanic aldehydes and the lowest levels of volatile phenols.Thus, considering the overall quality of the brandies, these results suggest the use of wood fragments to be an interesting alternative technology. On the other hand, the chemical analysis of the brandies showed the possibility of discriminating the ageing technologies based on odourant compound levels.

Keywords: Brandies; Maturation; Wood fragments; Odourants; Sensory profile

Sensory dimension of wine typicality related to a terroir by Quantitative Descriptive Analysis, Just About Right analysis and typicality assessment by Yves Cadot; Soline Caillé; Alain Samson; Gérard Barbeau; Véronique Cheynier (pp. 53-62).

The distinctive French wine style “Anjou Village Brissac” was investigated through Quantitative Descriptive Analysis by a sensory expert panel, through Just About Right analysis by wine experts, and through assessment of the typicality by wine experts. Typicality was defined as perceived representativeness, with good examples of the concept being considered more typical. Wine experts were producers, winemakers, and enologists from the area.Three types of data were used: (i) quantitative descriptive data on a non-structured scale, (ii) preference data that corresponded to a global typicality index for the wine on a non-structured scale, (iii) data collected on a Just About Right non-structured scale, where the middle of the scale, for each attribute, corresponded to Just About Right, an ideal of typicality for wine experts. The two panels, sensorial experts and wine experts, rated 24 Cabernet franc wines from different French “Appellation d’Origine Contrôlée”, including two-thirds “Anjou Village Brissac”. Single factor analysis was performed on each panel's data, and results were compared. Multifactor analysis was performed with the data of both panels to highlight the correspondence between the panels. ANOVAs conducted on the differences to the ideal scores permitted the wines to be sorted according to the similarity of their profiles. A penalty analysis was performed to determine, for each attribute, if the rankings on the Just About Right scale were related to significantly different results in the preference scores. Therefore, multivariate analysis of Just About Right scales served (i) to show an ideal point, (ii) to point out the distance between each product, (iii) and to evaluate the consensus of producers.The results showed the relevance of the sensory expert panels in discriminating the products. The panel of wine experts proved relevant for characterizing the global quality of the wines but did not appear consensual for some attributes. Some attributes from the wine expert panel could be explained by precise descriptors generated by the sensory expert panel. Typicality ratings were considered in relation with descriptive ratings, for example astringency and color attributes. The results presented in this study suggest the usefulness of these sensory techniques for describing wine typicality related to a terroir.

Keywords: Just About Right analysis; Quantitative Descriptive Analysis; Penalty analysis; Wine typicality

Qualitative data analysis for an exploratory sensory study of grechetto wine by Marco Esti; Ricardo L. González Airola; Elisabetta Moneta; Marina Paperaio; Fiorella Sinesio (pp. 63-67).

Grechetto is a traditional white-grape vine, widespread in Umbria and Lazio regions in central Italy. Despite the wine commercial diffusion, little literature on its sensory characteristics is available. The present study is an exploratory research conducted with the aim of identifying the sensory markers of Grechetto wine and of evaluating the effect of clone, geographical area, vintage and producer on sensory attributes.A qualitative sensory study was conducted on 16 wines, differing for vintage, Typical Geographic Indication, and clone, collected from 7 wineries, using a trained panel in isolation who referred to a glossary of 133 white wine descriptors. Sixty-five attributes identified by a minimum of 50% of the respondents were submitted to a correspondence analysis to link wine samples to the sensory attributes. Seventeen terms identified as common to all samples are considered as characteristics of Grechetto wine, 10 of which olfactory: fruity, apple, acacia flower, pineapple, banana, floral, herbaceous, honey, apricot and peach.In order to interpret the relationship between design variables and sensory attributes data on 2005 and 2006 wines, the 28 most discriminating descriptors were projected in a principal component analysis. The first principal component was best described by olfactory terms and the second by gustative attributes. Good reproducibility of results was obtained for the two vintages.For one winery, vintage effect (2002–2006) was described in a new principal component analysis model applied on 39 most discriminating descriptors, which globally explained about 84% of the variance. In the young wines the notes of sulphur, yeast, dried fruit, butter, combined with herbaceous fresh and tropical fruity notes (melon, grapefruit) were dominant. During wine aging, sweeter notes, like honey, caramel, jam, become more dominant as well as some mineral notes, such as tuff and flint.

Keywords: Grechetto; wine; Sensory evaluation; Correspondence analysis

Volatile and sensory profile of organic red wines produced by different selected autochthonous and commercial Saccharomyces cerevisiae strains by R.M. Callejon; A. Clavijo; P. Ortigueira; A.M. Troncoso; P. Paneque; M.L. Morales (pp. 68-75).

Organic wines were produced at pilot scale to select the best autochthonous and commercial yeast strains to obtain wines with high organoleptic qualities. We tested the behaviour of five S. cerevisiae yeast strains and determined their volatile composition and organoleptic characteristics by sensory analysis. A total of 51 volatile compounds were quantified in the wines produced. The concentration of most of the volatile compounds was significantly influenced depending on which yeast strain was inoculated. The differences observed in the volatile composition of the wines appear to be quantitative rather than qualitative. In general, acetals were the most abundant group of volatile compounds in all the samples studied, followed by alcohols without ethanol. The highest contents of volatile compounds were found in two of the wines produced by autochthonous yeast strains. The results obtained in the sensory analysis suggest that autochthonous yeast produced wines of higher organoleptic quality because this sample gave the highest value for the general impression attribute.

Keywords: Organic red wine; Yeast; Volatile compounds; Sensory analysis; HS-SBSE-TDU-GC–MS

Development of a microwave assisted extraction method for the analysis of 2,4,6-trichloroanisole in cork stoppers by SIDA–SBSE–GC–MS by Jochen Vestner; Stefanie Fritsch; Doris Rauhut (pp. 76-80).

The aim of this research work was focused on the replacement of the time-consuming soaking of cork stoppers which is mainly used as screening method for cork lots in connection with sensory analysis and/or analytical methods to detect releasable 2,4,6-trichloroanisole (TCA) of natural cork stoppers.Releasable TCA from whole cork stoppers was analysed with the application of a microwave assisted extraction method (MAE) in combination with stir bar sorptive extraction (SBSE). The soaking of corks (SOAK) was used as a reference method to optimise MAE parameters. Cork lots of different quality and TCA contamination levels were used to adapt MAE. Pre-tests indicated that an MAE at 40°C for 120min with 90min of cooling time are suitable conditions to avoid an over-extraction of TCA of low and medium tainted cork stoppers in comparison to SOAK. These MAE parameters allow the measuring of almost the same amounts of releasable TCA as with the application of the soaking procedure in the relevant range (<25ngL⁻¹ releasable TCA from one cork) to evaluate the TCA level of cork stoppers.Stable isotope dilution assay (SIDA) was applied to optimise quantification of the released TCA with deuterium-labelled TCA (TCA-d₅) using a time-saving GC–MS technique in single ion monitoring (SIM) mode.The developed MAE method allows the measuring of releasable TCA from the whole cork stopper under improved conditions and in connection with a low use of solvent and a higher sample throughput.

Keywords: 2,4,6-Trichloroanisole; Microwave; Stir bar sorptive extraction (SBSE); Stable isotope dilution assay (SIDA); Cork taint; Gas chromatography; Mass spectrometry

Determination of the impact of bottle colour and phenolic concentration on pigment development in white wine stored under external conditions by Chantal Maury; Andrew C. Clark; Geoffrey R. Scollary (pp. 81-86).

The exposure to sunlight of a Sauvignon blanc wine stored in bottles of different colours has been examined. Wine in darker bottles (Antique Green and French Green) showed considerably more colour development than wine in clear (Flint) or lighter (French Green) bottles, provided a high concentration of catechin-type phenolic compounds was present. Xanthylium pigments were identified by LC–MS as one of the main contributing phenolic pigments to the increased colour in the dark bottles. This is the first observation of yellow xanthylium pigments in a white wine. A Principal Component Analysis of the variation in absorbance measurements at Day 59 of the exposure further confirmed the importance of bottle colour on the result. One component, dominated by the darker Antique Green and Classic Green, reflected the development of colour at 440 and 520nm. The second component, to which the Flint and French Green bottles contributed the most, was based on a decrease in the 280nm absorbance. The implication of these results for the safe storage of wine is discussed.

Keywords: Abbreviations; UV; ultra-violet; HPLC–DAD; high performance liquid chromatography–diode array detection; LC–MS; liquid chromatography–mass spectrometryUltra-violet–visible; White wine; Oxidation; Sunlight; Bottle colour; Xanthylium cations

Comparison of three methods for accurate quantification of hydrogen sulfide during fermentation by Maurizio Ugliano; Paul A. Henschke (pp. 87-91).

Two analytical approaches for the rapid measurement of hydrogen sulfide (H₂S) have been compared to a reference method for their potential application as a rapid procedure for the quantification of H₂S formed during alcoholic fermentations. In one case, silver nitrate, lead acetate, and mercuric chloride selective detector tubes for the analysis of H₂S in air were investigated. In the other case, a commercially available kit for the diagnosis of nitrogen starvation in wine fermentations, which is based on the detection of H₂S, was investigated. Both methods exhibited excellent linearity of response, but the mercuric chloride tube was found to suffer from interferences due to the concomitant presence of mercaptans, which resulted in erroneous H₂S quantification. A comparative study between the two methods studied and the cadmium hydroxide/methylene blue reference method commonly used to monitor H₂S indicate that the two new methods displayed better recoveries at low H₂S concentrations, besides being more rapid and economical. The two new methods were successfully used to quantify production of H₂S in different grape juice fermentations. The suitability of each method for the study of specific aspects of H₂S production during fermentation is discussed.

Keywords: Hydrogen sulfide; Detector tubes; Nitrogenius; ^®; kit; Fermentation; Wine; Yeast

Micro-oxygenation strategy depends on origin and size of oak chips or staves during accelerated red wine aging by María Del Álamo; Ignacio Nevares; Laura Gallego; Brígida Fernández de Simón; Estrella Cadahía (pp. 92-101).

The practice of wine aging in stainless steel tank involves storing wine in contact with wood and dosing it with small oxygen quantities in order to obtain a final wine more stable in time and with the same characteristics of barrel-aged wines. Oxygen dosing is a key factor and, to achieve a correct development of wine, needs to be applied according to wine necessities and to the kind of wood chosen. This paper shows the results obtained from the study of oxygen required by a same wine aged in tanks with different alternative products (chips and staves) made of American (Q. alba), French (Q. petraea) and Spanish oak (Q. pyrenaica), with a strategy of micro-oxygenation as required. The results indicate that the size and origin of the wood used determine the oxygen management during the process. In fact, wine treated with big pieces (staves) consumes more oxygen and, with regard to wood origin, wine aged with French oak (Q. petraea) products needs of a higher oxygen dosage.

Keywords: Aging; Chips; Colour; Q.; alba; Q.; petraea; Q.; pyrenaica; Microoxygenation; Oxygen; Phenolic compounds; Red wine; Staves

Reactivity of volatile thiols with polyphenols in a wine-model medium: Impact of oxygen, iron, and sulfur dioxide by Maria Nikolantonaki; Igor Chichuc; Pierre-Louis Teissedre; Philippe Darriet (pp. 102-109).

As volatile thiols are nucleophiles, they are capable of additional reactions with electrophiles. In enology, this concerns reactions between volatile or non-volatile thiols and oxidized phenolic compounds. Initial studies concerning the reactivity of volatile thiols with polyphenols showed that (+)-catechin played a detrimental role in the level of 3-sulfanylhexan-1-ol (3SH), in the absence of sulfur dioxide. Our experiment revealed that (−)-epicatechin was more reactive with volatile thiols than (+)-catechin. Furthermore, Fe (III) was shown to play a crucial role in catalyzing polyphenol oxidation reactions, by affecting the direct reaction of phenolic compounds with oxygen. It was noted that, even if the volatile thiols studied were members of the same chemical family, they exhibited a different behavior pattern under oxidation conditions. 2-furanmethanethiol (2FMT) was more reactive than 3-sulfanylhexan-1-ol with both (+)-catechin and (−)-epicatechin. In contrast, 4-methyl-4-sulfanylpentan-2-one (4MSP) was less reactive with these phenolics. Additionally, the vital role of sulfur dioxide in protecting 3-sulfanylhexan-1-ol, 2-furanmethanethiol, and 4-methyl-4-sulfanylpentan-2-one was demonstrated in the model medium.

Keywords: Volatile thiols; Oxygen; Phenolic compounds; Iron; Sulfur dioxide; Reactivity

Heating and reduction affect the reaction with tannins of wine protein fractions differing in hydrophobicity by Matteo Marangon; Simone Vincenzi; Marco Lucchetta; Andrea Curioni (pp. 110-118).

During the storage, bottled white wines can manifest haziness due to the insolubilisation of the grape proteins that may ‘survive’ in the fermentation process. Although the exact mechanism of this occurrence is not fully understood, proteins and tannins are considered two of the key factors involved in wine hazing, since their aggregation leads to the formation of insoluble particles. To better understand this complex interaction, proteins and tannins from the same unfined Pinot grigio wine were separated. Wine proteins were then fractionated by hydrophobic interaction chromatography (HIC). A significant correlation between hydrophobicity of the wine protein fractions and the haze formed after reacting with wine tannins was found, with the most reactive fractions revealing (by SDS-PAGE and RP-HPLC analyses) the predominant presence of thaumatin-like proteins. Moreover, the effects of both protein heating and disulfide bonds reduction (with dithiotreithol) on haze formation in the presence of tannins were assessed. These treatments generally resulted in an improved reactivity with tannins, and this phenomenon was related to both the surface hydrophobicity and composition of the protein fractions. Therefore, haze formation in wines seems to be related to hydrophobic interactions occurring among proteins and tannins. These interactions should occur on hydrophobic tannin-binding sites, whose exposition on the proteins can depend on both protein heating and reduction.

Keywords: Abbreviations; TL-proteins; thaumatin-like proteins; PR-proteins; pathogenesis-related proteins; HIC; hydrophobic interaction chromatography; DTT; dl; -dithiotreithol; PAS; Periodic Acid-Schiff stain; MW; molecular weight; MWCO; molecular weight cut off; Mr; relative mobilityWine; Thaumatin-like proteins; Chitinases; Haze; Tannin; Hydrophobicity

Alternatives for sample pre-treatment and HPLC determination of Ochratoxin A in red wine using fluorescence detection by Catherine Tessini; Claudia Mardones; Dietrich von Baer; Mario Vega; Erika Herlitz; Roberto Saelzer; Jorge Silva; Olga Torres (pp. 119-126).

Ochratoxin A is a mycotoxin widely studied due to its nephrotoxic, immunotoxic, teratogenic and carcinogenic effects. The European Commission has fixed maximum limits for Ochratoxin A in wines and in other foods. In order to determine Ochratoxin A levels in red wine, the present paper contrasts and discusses the results of a systematic study of analytical parameters for sample pre-treatment using different immunoaffinity cartridges as well as C-18 cartridges with three solvent combinations. The direct injection of wine into two types of C-18 chromatographic columns (conventional packed column and monolithic column) is evaluated as screening method. In all cases, the analysis was carried out using HPLC with fluorescence detection. The results show statistical differences when 3 types of immunoaffinity columns were used, while higher recoveries were obtained for C-18 cartridges using acetonitrile as extraction solvent. Repeatability and accuracy of immunoaffinity and C-18 sample pre-treatment were statistically comparable ( α=0.05). Their sensitivity was also comparable, although more favorable detection limits were obtained using the immunoaffinity treatment (0.01μgL⁻¹) in comparison with C-18 treatment (0.09μgL⁻¹). Considering the maximal allowed concentration of Ochratoxin A in wine (2.00μgL⁻¹), both methods are suitable for its determination in wine. Both methods were applied to determine this toxin in 154 wine samples, and the quantitative results demonstrated statistic comparability ( α=0.05). These results were also confirmed from the qualitative point of view using a GC–MS method. To find an easy screening method, based on a recent publication, a monolithic HPLC column and 2 conventional packed columns were tested for Ochratoxin A determination in real wine samples by direct injection, without previous clean-up. The results show that this procedure is not useful at the concentration levels usually found in wine and although shorter time is required when using the monolithic columns even with the chromatographic analysis. Finally, based on the results, it was concluded that the combination of C-18 cartridges with conventional particle packed columns and HPLC–FLD is the most appropriate alternative for Ochratoxin A analysis in wine. Indeed, considering cost, sensitivity and selectivity, this method can be used in broad prospective programs.

Keywords: Ochratoxin A; Wine; High performance liquid chromatography-fluorescence detection; Immunoaffinity; Solid phase extraction; Gas chromatography-mass spectrometry

Comparison of methods for estimating phenolic maturity in grapes: Correlation between predicted and obtained parameters by Nikolaos Kontoudakis; Mireia Esteruelas; Francesca Fort; Joan Miquel Canals; Fernando Zamora (pp. 127-133).

With the aim of determining the real predictive ability of three methods for measuring phenolic maturity (Glories, ITV and Cromoenos), representative grapes of Merlot, Cabernet sauvignon, Grenache and Tempranillo were harvested at three different ripening levels. The grapes were vinified by triplicate and were also used for phenolic maturity estimation. After that, color intensity, CIELAB coordinates, anthocyanins by spectrometry and HPLC and total phenolics were analysed in wines and also in the different extracts from the three extraction methods. Statistical analysis of data was carried out to determine the real performance of prediction of the different methods. Glories method predicted reasonably the color intensity, CIELAB coordinates and the concentration of anthocyanins and total phenolics in wine although it needs a lot of time and it requires working carefully. On the other hand, Cromoenos method predicted similarly or even better the color and phenolic composition of wine. This method also presents the advantage of being much faster and easier to apply. In contrast, although the ITV method provided reasonable results for anthocyanins and total phenolic compounds its color prediction was not adequate.

Keywords: Phenolic maturity; Glories; Institut Français de la Vigne et du Vin method; Cromoenos; Predictive ability

Colour and pigment composition of red wines obtained from co-maceration of Tempranillo and Graciano varieties by Matilde García-Marino; José Miguel Hernández-Hierro; Julián C. Rivas-Gonzalo; M. Teresa Escribano-Bailón (pp. 134-142).

The Vitis vinifera L. cv Graciano is often used as an integral component of Rioja wines because it is considered to contribute significantly to the quality of Tempranillo based wines. The aim of this work was to determine the effect of the incorporation of the Graciano variety on the colour and pigment composition of Tempranillo based wine and to evaluate the possible differences between blending Tempranillo with Graciano varietal wine (W wine) in contrast to a wine obtained by mixing these two grape varieties in the prefermentative maceration step (M wine). Results indicated that pigment extraction and retention in M wine was higher than in Tempranillo (T) wine. Colour differences (ΔEab*) between wines at the end of the study (after 12 months in bottles) were detectable by the human eye (ΔEab*≥3) in all cases except forT andW. These wines have indistinguishable colours even when using analytical methods (ΔEab*≤1). Regarding hue h_ab,T andW presented higher values (more orange-red) than Graciano (G) andM (more blue-red). PCA allowed the colour and composition analytical data to be reduced to a small number of principal components that could separate successfully betweenT andG wines and between the different steps of the winemaking process.

Keywords: Wine colour; Anthocyanins; Tempranillo; Graciano; Co-maceration; Principal component analysis

Identification of a β-d-glucopyranoside precursor to guaiacol in grape juice following grapevine exposure to smoke by Y. Hayasaka; K.A. Dungey; G.A. Baldock; K.R. Kennison; K.L. Wilkinson (pp. 143-148).

The presence of the β-d-glucopyranoside of guaiacol (glucoside) in juice of grapes following grapevine exposure to smoke was investigated. The glucoside was synthesized as a reference compound and an HPLC–MS/MS method was developed for its detection in juice. The glucoside was found in the juice extracts of grapes exposed to bushfire smoke, as well as grapes experimentally exposed to smoke. Compared to the control (unsmoked) juice sample, the experimentally smoked juice contained a significant amount of the glucoside, indicating glucosylation of guaiacol occurred following grapevine smoke exposure. The reference compound, and the glucoside found in the smoked juice samples were less susceptible to acid treatment but virtually disappeared after enzyme treatment with β-glucosidase. The susceptibility of the glucoside to enzyme hydrolysis could be one reason for the release of guaiacol from smoke affected grapes during fermentation.

Keywords: Grapes; Guaiacol; Guaiacol β-; d; -glucopyranoside; HPLC–MS/MS; Smoke; Wine

A robust method for quantification of volatile compounds within and between vintages using headspace-solid-phase micro-extraction coupled with GC–MS – Application on Semillon wines by Laure Rebière; Andrew C. Clark; Leigh M. Schmidtke; Paul D. Prenzler; Geoffrey R. Scollary (pp. 149-157).

A headspace-solid-phase micro-extraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS) method has been developed to quantify a range of volatile compounds in Hunter Valley Semillon wines. The fibre selected for the method was a 50/30μm divinylbenzene/carboxen/polydimethylsiloxane fibre, a three-phase fibre that allows extraction and desorption of a wide range of volatile compounds of different chemical functionalities and polarities. Four internal standards, methyl isobutyl ketone, n-dodecane, 4-methyl-2-pentanol and ethyl nonanoate were used to monitor the SPME fibre extraction efficiency and integrity. Fibre integrity was monitored by plotting the ratio of the peak area for each internal standard divided by the sum of the peak area for all internal standards as a function of analysis number. The advantage of using four internal standards for better quality control of the fibre integrity is described. The identity of twenty-one volatile compounds was ascertained by comparison of their chemical characteristics (retention indices, mass spectra) with reference compounds using two columns of different polarities. Quantification was achieved using calibration curves constructed for each compound with linear regression equations having correlation coefficients ( R²) ranging from 0.9717 to 0.9999. The method was applied to two Semillon wines (recent vintage and aged) representative of the Hunter Valley styles. As is typical of white wines, 3-methyl-1-butanol was quantified as the most concentrated volatile compound (83 and 66mgL⁻¹ for the 2006 and the 1996 wines, respectively). The study highlights the use of well-defined procedures to ensure integrity of quantitative data where several fibres may be required during an extended study over one or more vintages.

Keywords: Gas chromatography–mass spectrometry; Solid-phase micro-extraction; Volatile compounds; White wine; Semillon; Internal standard

A HPLC fluorescence-based method for glutathione derivatives quantification in must and wine by Stéphanie Marchand; Gilles de Revel (pp. 158-163).

A simple and automated high performance liquid chromatography (HPLC) method for the separation and quantitative determination of γ-glutamylcysteine and reduced glutathione (GSH) in wines is reported. This technique involves the use of a pre-column derivatization with 2,3-naphthalenedialdehyde (NDA), an isocratic separation in presence of β-cyclodextrine and a fluorimetric detection. The quantification of oxidized glutathione (GSSG) has also been studied, for the first time in wines, using an additive pre-derivatization step for reduction using glutathione reductase. The method has been designed for use in laboratories with limited equipment. The assay has been optimized and presents very good performances in terms of sensitivity and selectivity. Then, it has been validated for linearity, LOD, LOQ, precision and accuracy.

Keywords: Oxidized and reduced glutathione; γ-glutamylcysteine; g-Wine; Quantification; Liquid Chromatography-fluorimetry

Foaming properties of various Champagne wines depending on several parameters: Grape variety, aging, protein and CO₂ content by Clara Cilindre; Gérard Liger-Belair; Sandra Villaume; Philippe Jeandet; Richard Marchal (pp. 164-170).

A comparison of the foaming parameters of various Champagne wines was undergone with two well distinct methods: (i) a classical gas-sparging method providing standardized but artificial effervescence conditions (the so-called Mosalux), and (ii) a computer assisted viewing equipment (CAVE), much closer to the real champagne tasting conditions. The latter one is the only apparatus which enables a thorough descriptive analysis of foam behavior, during the pouring process of a sparkling wine, and from the end of its pouring. Various Champagne wines elaborated from two grape varieties (Chardonnay and Pinot Meunier) and having experienced different aging-periods (15 months and 5 years) were analyzed and compared to a model sparkling wine, elaborated from a model base wine (devoid of grape colloids). The CO₂ and protein content was also investigated to discuss the foaming behavior of these wines. A significant loss of the CO₂ content during aging was observed and might be the reason for the worse foaming properties of the old champagnes, as determined with CAVE. It is worth noting that contradictory foaming parameters were obtained through the Mosalux method, which is indeed more intrusive than the CAVE, and finally far from the real champagne tasting conditions, since it requires filtration and champagne degassing prior experiment.

Keywords: Champagne; Foaming properties; CO; ₂; Effervescence; Protein; Yeast; Aging; Champagne tasting

Development of a fractionation method for the detection and identification of oak ellagitannins in red wines by Ignacio García-Estévez; M. Teresa Escribano-Bailón; Julián C. Rivas-Gonzalo; Cristina Alcalde-Eon (pp. 171-176).

During maturation and ageing in oak barrels wines improve their organoleptic properties. Ellagitannins can be released from wood to the wine and be involved in oxidation reactions and seem to influence the astringency and colour properties of the wine.Nevertheless, the ellagitannins levels are lower than those of other wine constituents and, consequently, they are not easily detected. This study has developed a two-step fractionation method consisting of a solid phase extraction in C-18 Sep-Pak^® cartridges followed by size exclusion chromatography in hand-packed Sephadex LH-20 minicolumn for the detection of oak ellagitannins in different types of wines. An HPLC method has also been developed which allows the separation of compounds with the same m/ z ratios, facilitating the ellagitannin identification by means of the mass spectrometric analyses. The main oak ellagitannins (grandinin, vescalagin, roburin E and castalagin) were isolated, detected separately and identified in a spiked wine and in three real ones, proving the usefulness of the fractionation method.

Keywords: Oak ellagitannins; Red wine; High performance liquid chromatography-diode array detection-mass spectrometry; Fractionation; Characterisation

Effect of freeze-drying and oven-drying on volatiles and phenolics composition of grape skin by C. de Torres; M.C. Díaz-Maroto; I. Hermosín-Gutiérrez; M.S. Pérez-Coello (pp. 177-182).

Grape skins are the part of the fruit with the highest amount of volatile and polyphenolic compounds. Volatile compounds give the fruit and other grape derivatives their flavour. Polyphenolic compounds are responsible for the colour of the fruit, juice and wine, and also act as very important natural antioxidant compounds. Dehydration is a method used to prevent the damage of these compounds over time. Nevertheless, in the case of volatile compounds, removing water can cause compound degradation or the evaporation of such compounds. This work studied two drying methods, freeze-drying and oven-drying, at 60°C, as skin preservation methods. The skins from two grape varieties, Carménère and Cabernet Sauvignon, were dried. Many volatile compounds, which are of interest in the aroma profile, were identified in both varieties as terpenes (linalool, etc.), sesquiterpenes (farnesol), norisoprenoids (vitispirane, etc.), C₆ alcohols (1-hexanol, etc.), etc., and their amount decreased significantly with the oven-drying method, in contrast to the freeze-drying method. Both phenolic compounds, anthocyanins and flavonols, were identified in fresh and dehydrated samples, thus resulting in the freeze-drying method being less aggressive than oven-drying methods.

Keywords: Dehydrated process; Skin grape; Volatile compounds; Phenolic compounds

Mechanical properties, phenolic composition and extractability indices of Barbera grapes of different soluble solids contents from several growing areas by Fabrizio Torchio; Enzo Cagnasso; Vincenzo Gerbi; Luca Rolle (pp. 183-189).

Phenolic compounds, extractable from grape skins and seeds, have a notable influence on the quality of red wines. Many studies have clearly demonstrated the relationship between the phenolic composition of the grape at harvest time and its influence on the phenolic composition of the red wine produced. In many previous works the evolution of phenolic composition and relative extractability was normally studied on grapes sampled at different times during ripening, but at the same date the physiological characteristics of grape berries in a vineyard are often very heterogeneous. Therefore, the main goal of the study is to investigate the differences among mechanical properties, phenolic composition and relative extractability of Vitis vinifera L. cv Barbera grape berries, harvested at the same date from several vineyards, and calibrated according to their density at three levels of soluble solids (A=235±8, B=252±8 and C=269±8gL⁻¹ sugar) with the aim of studying the influence of ripeness stages and growing locations on these parameters.Results on mechanical properties showed that the thickness of the berry skin (Sp_sk) was the parameter most affected by the different level of sugars in the pulp, while different skin hardnesses, evaluated by the break skin force ( F_sk), were related to the cultivation sites. The latter were also observed to influence the mechanical characteristics of seeds.Generally, the anthocyanin content increased with the level of soluble solids, while the increase in the tannin content of the berry skin and seeds was less marked. However, significant changes in flavanols reactive to vanillin in the seeds were found.The cellular maturity index (EA%) was little influenced by the soluble solids content of grapes.

Keywords: Skin hardness; Cellular maturity index; Texture analysis; Anthocyanin; Proanthocyanidin

Aromatic potential of botrytized white wine grapes: Identification and quantification of new cysteine- S-conjugate flavor precursors by Cécile Thibon; Svitlana Shinkaruk; Michael Jourdes; Bernard Bennetau; Denis Dubourdieu; Takatoshi Tominaga (pp. 190-196).

Sweet wines made from botrytized grapes contain much higher concentrations of volatile thiols, especially 3-sulfanylhexan-1-ol (3SH), than dry white wines. Three new specific volatile thiols (3-sulfanylpentan-1-ol (3SP), 3-sulfanylheptan-1-ol (3SHp), and 2-methyl-3-sulfanylbutan-1-ol (2M3SB) were recently identified in Sauternes wines. Like most volatile thiols, these compounds were almost totally absent from must, mainly being formed during alcoholic fermentation. In this work, we describe the identification and quantification of three new cysteine- S-conjugate precursors in must made from Botrytis-infected grapes. S-3-(pentan-1-ol)-l-cysteine (P-3SP), S-3-(heptan-1-ol)-l-cysteine (P-3SHp), and S-3-(2-methylbutan-1-ol)-l-cysteine (P-2M3SB) were identified by direct GC–MS analysis of their derivative forms obtained by silylation of an enriched fraction, isolated from must by affinity chromatography. Concentrations were considerably higher when Botrytis cinerea had developed on the grapes. In botrytized must, the mean levels of P-3SP, P-3SHp, and P-2M3SB were in the vicinity of 700, 50, and 500nM, respectively, whereas concentrations in healthy must ranged from 0 to 50nM. This indicated that these three new sulfanyl alcohols, responsible for the characteristic aroma of botrytized wines, were formed by the yeast metabolism during alcoholic fermentation from the corresponding non-volatile cysteine- S-conjugate precursors. Moreover, these results highlighted the predominant role of botrytization in developing grape aroma potential.

Keywords: Sweet wine; Aroma precursor; Cysteine-; S; -conjugate; GC derivatization; Vitis vinifera; Botrytis cinerea

Comparison of extraction techniques and mass spectrometric ionization modes in the analysis of wine volatile carbonyls by Julián Zapata; Laura Mateo-Vivaracho; Juan Cacho; Vicente Ferreira (pp. 197-205).

This work presents a comparative study of the analytical characteristics of two methods for the analysis of carbonyl compounds in wine, both based on the derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA). In the first method derivatives are formed in the solid phase extraction (SPE) cartridge in which the analytes have been previously isolated, while in the second method derivatives are formed in a solid phase microextraction (SPME) fibre saturated with vapors of the reagent and exposed to the sample headspace. In both cases detection has been carried out by electron impact (EI) or negative chemical ionization (NCI) mass spectrometry. The possibility of determining haloanisols simultaneously has been also considered.The method based on SPE presents, in general, better analytical properties than the SPME one. Although linearity was satisfactory for both methods ( R²>0.99), repeatability of the SPE method (RSD<10%) was better than that obtained with SPME (9%

Keywords: Carbonyls; Trichloroanisol; Solid phase extraction (SPE); Solid phase microextraction (SPME); Negative chemical ionization (NCI); Wine

Application and comparison of four selected procedures for the isolation of cell-wall material from the skin of grapes cv. Monastrell by R. Apolinar-Valiente; I. Romero-Cascales; J.M. López-Roca; E. Gómez-Plaza; J.M. Ros-García (pp. 206-210).

In order to choose an appropriate cell-wall material (CWM) isolation procedure in grapes cv. Monastrell, four different standard procedures have been tested, and a comparison made of the amount of cell-wall material obtained, its composition and morphology. The CWM was isolated as the 70% ethanol insoluble residue (de Vries method), as the absolute ethanol insoluble residue filtered sequentially through nylon mesh (Nunan method), as the insoluble residue in sodium deoxycholate–phenol–acetic acid–water (Selvendran method) and as the N-[2-hydroxyethyl]-piperazine-N′-2-ethanesulfonic acid (HEPES) insoluble residue (Vidal method). All extractions were done in triplicate and the efficiency of the extractive procedure established. Carbohydrates, proteins, and phenolic compounds were analysed, as the main constituents of CWM. The morphology of the isolated CWM was visualized by scanning electron microscopy (SEM). The Selvendran method had the highest efficiency, while the Nunan method had the lower one. Regarding the carbohydrates composition, the four different CWM were rich in uronic acids and glucose, together with varying amounts of arabinose, xylose, mannose and galactose. The Selvendran method had the lower value of total carbohydrates and the CWM shows more plasmatic membrane impurities in SEM images. The chemical results of the Vidal and de Vries methods were quite similar, but the Vidal method was more time consuming than the de Vries method. According to the results, the de Vries method was chosen to produce a representative cell-wall material fraction from Monastrell grapes skin.

Keywords: Cell-wall; Monastrell; Isolation; Polysaccharides; Skin

Effect of size, seasoning and toasting in the volatile compounds in toasted oak wood and in a red wine treated with them by B. Fernández de Simón; E. Cadahía; M. del Álamo; I. Nevares (pp. 211-220).

The increasing demand for wood for barrel-making in addition to the rapid extension of alternative aging system, have led to looking into the possibility of utilizing Spanish oak. Quercus pyrenaica is the species that predominates in Spain, and the chemical composition of its heartwood (ellagitannins, low molecular weight phenolic and volatile compounds) and its incidence in characteristics of wine are similar to that of other species that are of recognized oenological quality for barrel-making, showing only quantitative differences with respect to French ( Quercus petraea) and American ( Quercus alba) species. However, at present, the quantity of good quality wood that we can obtain from the Q. pyrenaica Spanish forest is limited. Hence, in the short term, and considering the high chemical oenological quality of Q. pyrenaica wood, we propose the utilizing of chips, segments, staves, and other oak alternatives for wine aging, which would be obtained from wooden remnants from barrel-making as well as from trees with small diameters or physical defects which would normally be inappropriate for cooperage. With regards to the latter idea, studies on special chip-making processes, and other oak wood pieces are being carried out, especially focused on reducing seasoning time, and to toasting optimization as a function of wood piece size, in addition to its behaviour when incorporated into the different alternative aging systems. We present in this study the effect of seasoning way (traditional or unconventional) on volatile composition of Q. pyrenaica chips and staves at three toasting levels (light, medium and heavy), and the evolution of the wood-released aromatic composition of a Spanish artificially aged wine, using these alternative products. The wines showed in general small differences in their oak-derived characteristics, which were more related to the wood piece size and the toasting intensity than to the seasoning way, and they could be linked with the concentrations of compounds as eugenol, furfural, and the cis and trans isomers of β-methyl-γ-octolactone.

Keywords: Quercus pyrenaica; Gas chromatography–mass spectrometry; Oak wood; Wine; Volatile compounds

Authenticity markers in Aglianico, Uva di Troia, Negroamaro and Primitivo grapes by Pasquale Tamborra; Marco Esti (pp. 221-226).

Aglianico, Negroamaro, Uva di Troia, and Primitivo, non-aromatic red grapes of southern Italy, were analyzed with respect to berry varietal markers, namely anthocyanins, flavonols, hydroxycinnamoyl tartaric acids (HPLC–DAD) and glycosidic aroma precursors (GC–MS) together with shikimic acid (HPLC–UV). In this study, we confirmed that the relative amount of grape glycosidic precursors from various terpene families was a helpful varietal discriminating factor. An additional decisive contribution to varietal differentiation was also provided by shikimic acid, acetylated forms of anthocyanins, cyanidin-3-O-glucoside, trans-caftaric and trans-coutaric acids. A three-dimensional model of principal component analysis was adopted to evidence the study results.

Keywords: Local Italian grapes; Glycosidic precursors; Shikimic acid; Anthocyanins; Terpenes; Hydroxycinnamoyl tartaric acids

Classification of Tempranillo wines according to geographic origin: Combination of mass spectrometry based electronic nose and chemometrics by Wies Cynkar; Robert Dambergs; Paul Smith; Daniel Cozzolino (pp. 227-231).

Rapid methods employing instruments such as electronic noses (EN) or gas sensors are used in the food and beverage industries to monitor and assess the composition and quality of products. Similar to other food industries, the wine industry has a clear need for simple, rapid and cost effective techniques for objectively evaluating the quality of grapes, wine and spirits. In this study a mass spectrometry based electronic nose (MS-EN) instrument combined with chemometrics was used to predict the geographical origin of Tempranillo wines produced in Australia and Spain. The MS-EN data generated were analyzed using principal components analysis (PCA), partial least squares discriminant analysis (PLS-DA) and stepwise linear discriminant analysis (SLDA) with full cross validation ( leave-one-out method). The SLDA classified correctly 86% of the samples while PLS-DA 85% of Tempranillo wines according to their geographical origin. The relative benefits of using MS-EN will provide capability for rapid screening of wines. However, this technique does not provide the identification and quantitative determination of individual compounds responsible for the different aroma notes in the wine.

Keywords: Electronic nose; Headspace; Geographical origin; Volatile compounds; Chemometrics; Mass spectrometry

Dissolved oxygen distribution during micro-oxygenation. Determination of representative measurement points in hydroalcoholic solution and wines by I. Nevares; M. del Alamo; C. Gonzalez-Muñoz (pp. 232-239).

Red wine tank aging is monitored by organoleptic analysis, therefore, it is necessary to use an objective parameter representing the process. Among the possible parameters to be checked, it stands out the knowledge of dissolved oxygen because it offers the possibility of anticipating undesirable situations that bring about too much oxidation. Dissolved oxygen measurement, with non-intrusive luminescent technology is becoming an effective alternative. Uncertainty arises when trying to choose the measuring point able to represent the entire tank since previous works have considered the existence of gradients throughout the volume of the treated wine.This paper shows the results obtained from the study of the existence and the quantification of gradients of the dissolved oxygen in a 15% hydroalcoholic solution during the micro-oxygenation process. Different measuring point placements are studied and the solutions to monitor the process by controlling a representative point are set out. A successful monitoring of a red wine tank aging with alternative oak products and adaptative micro-oxygenation has proved that an objective control of the process is, indeed, possible.

Keywords: Consumed oxygen; Dissolved oxygen; Luminescence; Red wine; Oxygen dosage; Micro-oxygenation

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Analytica Chimica Acta (v.660, #1-2)