Absorption of chloroanisoles from wine by corks and by other materials

Sixty 750 mL bottles of a white wine were each spiked with deuterium-labelled 2,4,6-trichloroanisole (d₅ TCA) and then sealed with a variety of wine corks. Thirty months later, approximately half of the d_5-TCA had been absorbed by each of the corks, regardless of supplier, bleaching treatment or whether the corks were natural or agglomerate. In addition to the added labelled TCA, every one of these corks also contained endogenous (i.e. unlabelled) TCA. Fifteen of the corks, mostly agglomerates, imparted some of their endogenous TCA into the wines. There was no direct relationship between the amount of endogenous TCA in the corks and that found in wines. The high variability in the distribution of endogenous TCA between wine and cork contrasts with the relatively uniform distribution of the d₅-_-TCA. This contrasting behaviour distinguishes between wines tainted prior to closure and wine tainted by corks. Natural bark corks in wine bottles can also absorb 2,3,4,6-tetrachloroanisole (TeCA) and pentachloro-anisole (PCA) from bottled wine. Bottle storage of commercial wines that had become tainted with TeCA and PCA during production resulted in the corks absorbing most of these two compounds, so that the wines were no longer tainted to a significant extent. Soaking whole corks in wine spiked with chloroanisoles, under conditions typically employed in the wine industry to test batches of corks for possible taint, resulted in most of the TCA in the wine being absorbed by the corks. Thus, if five corks are being soaked in wine in order to test for taint, four sound corks could reabsorb TCA that had leached into the surrounding wine from a single contaminated cork, reducing the concentration of TCA to a point where it escapes detection. Soaking corks singly rather than in groups of five will therefore be a more sensitive method of screening batches of corks for taint than soaking them in groups of five. Plastic materials such as the lids of glass containers used to store wine samples were also able to absorb chloroanisoles via both direct liquid contact and the vapour phase. Wine cask bladders and polyethylene film were particularly effective in removing TCA from wine.     

Arsenic content in some Spanish wines. Influence of the wine-making technique on arsenic content in musts and wines

All of the essential technological means of treating grapes, must and wine were examined systematically. The main reasons for the differences in the arsenic (As) content of rosé and red wines are explained. In this study a relationship has been found between the As level and the wine-making technique. Rosé wines contain more As than red wines because they require a shorter period of contact with the skins. In order to prove this, the average values for the rosé and red wine samples from the same winery were compared.     

葡萄酒中卤苯甲醚类化合物检测技术研究进展

卤苯甲醚类化合物能导致葡萄酒产生霉味、泥土味或令人不愉快味道,主要来自于软木塞和橡木桶,极大地影响葡萄酒的感官质量。该文综述了葡萄酒中卤苯甲醚类物质的组成、来源和危害,重点阐述了在检测葡萄酒中卤苯甲醚类物质时的浓缩萃取技术、检测技术及其进展,为我国葡萄酒产业质量监控、检测此类物质和葡萄酒安全提供参考。     

The role of corks in oxidative spoilage of white wines

The permeability of corks to oxygen was examined by comparing the level of browning and the concentration of the antioxidants, free and total sulfur dioxide and ascorbic and erythorbic acids in wines bottled and sealed with two cork types and stored in an atmosphere of either nitrogen, oxygen or air. Three different batches of corks that had been treated with peroxide during processing, representing one cork type, and a batch of corks that had been treated with chlorine during processing representing the second cork type, were taken for the study. In bottled wines stoppered with one of the peroxide-treated corks (Cork A), there was a higher level of browning and a greater loss of the antioxidants in those wines in bottles stored under oxygen and air than that in the wines in bottles stored under nitrogen, indicating that corks of this batch were permeable to oxygen. There was no significant difference in the loss of ascorbic and erythorbic acid or the level of browning from bottled wines stored under the three gases and sealed with the chlorine-treated corks (Cork C). For the other two peroxide-treated corks (Corks B and D), there was no significant difference in the level of browning or loss of the antioxidants from bottled wines stored under the three gases and sealed with Cork B, nor was there a significant difference in the level of browning or loss of free or total sulfur dioxide from bottled wines stored under the three gases and sealed with Cork D. From comparative data, it was evident that oxidation of the wines sealed with Corks B and D was due to compounds in the corks rather than oxygen permeation through the corks, or oxygen ingress at bottling. Because the bottles of wine selected for this study were from batches that had already exhibited sporadic oxidation, the results found are indicative, but not necessarily representative, of the properties of all peroxide- and chlorine-treated cork types used in the wine industry.     

The analysis of 2,4,6-trichloroanisole and other chloroanisoles in tainted wines and corks

A new method has been developed for the analysis, by gas chromatography/mass spectrometry, of 2,4,6-trichloroanisole (TCA) and other chloroanisoles in cork-tainted wines, using a polydeuterated form of TCA as an internal standard. In a survey of wines presented at a wine assessment course, 4.8% (i.e. 18 bottles out of 374) were assessed by at least 20% of the participants as being affected by cork taint. TCA was present in each of these 18 wines at a concentration close to, or above the sensory detection threshold. All cases of taint seen by the participants could therefore be attributed, at least in part, to the presence of TCA, and this in turn could be attributed to the cork, since variation in apparent taint between bottles of the same wine was observed in every case. TCA was also found in the corks from the wines. Randomly selected bottles of wines considered to be affected by a high proportion of cork taint, and the corks from those bottles, were also analysed. There was considerable variation in the distribution of TCA and other chloroanisoles between wine and cork. In many cases, chloroanisoles were found only in the cork. TCA in corks was accompanied by varying amounts of 2,4– or 2,6-dichloroanisoles, 2,3,4,6-tetrachloroanisole and pentachloroanisole, indicating more than one origin for chloroanisoles in corks. No chloroanisoles, other than those derived by methylation of products formed by non-enzymatic chlorination of phenol, were detected in any of the samples.     

不同透氧率的瓶塞对瓶储两年葡萄酒感官品质的影响

该研究采用三种不同透氧率瓶塞（经典、至尊500和至尊300）对赤霞珠干红和贵人香干白葡萄酒进行两年的瓶内储存,通过测定不同瓶塞葡萄酒溶解氧（DO）、顶端空间游离氧（HSO）含量、单体花色苷总含量、CIELab颜色参数、挥发性香气成分及感官评价,分析不同瓶塞对葡萄酒感官品质的影响。结果表明,不同瓶塞葡萄酒中DO和HSO含量下降幅度为经典>至尊500>至尊300。a*值、b*值、色度（Cab值）和色调（hab值）与单体花色苷总含量呈极显著正相关（P<0.01）,而L*值与之呈极显著负相关（P<0.01）。不同瓶塞赤霞珠干红葡萄酒中共检测出30种挥发性香气成分,包括4种醇类,11种酯类,8种有机酸类,1种萜烯类和6种酚类。至尊瓶塞感官品质优于经典瓶塞,至尊500与至尊300之间无明显差异。     

The impact of closure type and storage conditions on the composition, colour and flavour properties of a Riesling and a wooded Chardonnay wine during five years' storage

This paper presents the results from an investigation to assess the development of a Riesling and a wooded Chardonnay wine over five years following the imposition of several treatments at bottling. The wines were bottled under a screw cap closure, two different natural corks, a synthetic closure and in a glass ampoule. In addition, the effect of storage orientation was investigated. The bottled wines were stored under controlled temperature and humidity conditions. Various analyses were carried out on replicate bottles from each treatment, including sulfur dioxide and ascorbic acid concentration, sensory analysis of appearance and aroma attributes, and spectral measures. The largest treatment effect resided with the nature of the closure. Wines sealed with the synthetic closure were relatively oxidised in aroma, brown in colour, and low in sulfur dioxide compared to wines held under the other closures. A struck flint/rubber ( reduced ) aroma was discernible in the wines sealed under the screw caps or in glass ampoules. Wines sealed under natural bark corks in this study showed negligible reduced characters. The bottle orientation during storage under the conditions of this study had little effect on the composition and sensory properties of the wines examined.     

Effect of wine style on the perception of 2,4,6-trichloroanisole,a compound related to cork taint in wine

2,4,6-Trichloroanisole (TCA) is a fungal metabolite that can contaminate cork stoppers and wines producing a very unpleasant mouldy odour (cork taint). Sensory control is very widely used for the detection of possible TCA presence in corks and wine, but the correct identification of TCA, especially at low concentrations, can be difficult. The aim of this study was to show how wine styles can affect the ability of the same panel to perceive TCA. For this purpose, a panel was selected, according to the panelists’ sensitivity to the TCA stimulus. The triangle test, a sensory difference test, was carried out by the panel with both white and red wines, using samples both free from TCA and spiked with known quantities of this contaminant. The results showed that the panelists identified the difference caused by the added TCA at different significance levels, depending on the wine style, so TCA detection was influenced by wine style for the selected panel.     

Analysis of Ochratoxin A in Wine by High-Resolution UHPLC-MS

A method for determination of ochratoxin A (OTA) in wines using a new-solid phase extraction clean-up procedure followed with ultra performance liquid chromatography (UHPLC)-Orbitrap MS based on two scan events (full-scan Fourier transform mass spectrometer [FTMS] and higher energy-induced collision dissociation[HCD] data-dependent MS/MS) in positive ionization mode has been developed. The limit of detection (LOD) was estimated at 0.46 μg l^?1 for white wine, 0.53 and 0.54 μg l^?1 for rosé and red wines, respectively. The limit of quantification (LOQ) was estimated at 1.57 μg l^?1 in white wine, 1.77 and 1.81 μg l^?1 in rosé and red wines. Recovery experiments were carried out with spiked samples at three concentration levels (2, 5 and 10 μg l^?1). The OTA recoveries in spiked white wine samples varied from 69.6 % to 99.8 %, while the recoveries for rosé and red wine samples were in the range of 63.0–110.2 % and 63.6–103.2 %, respectively. Finally, based on the results, it is concluded that the combination of C18 cartridge with conventional particle packed columns and UHPLC LTQ-Orbitrap XL is an appropriate procedure for OTA analysis in wines.     

Measurement of the colour of white and rosé wines in visual tasting conditions

We have designed a colour measurement method that reproduces the conditions found during visual colour assessment of wines. In particular the illumination, background, wine sampler and the relative positions of sampler, illumination and observer have been controlled. Using this method, the colour of 33 white wines and 33 rosé wines was measured and expressed in terms of the CIELAB colour coordinates. Colour of wine samples was also assessed by expert wine tasters. White wines were classified into three colour categories: Straw-yellow, Yellow-gold and Yellow-green. Rosé wines were classified into four colour categories: Raspberry, Strawberry, Redcurrant and Salmon. The performance of CIELAB colour coordinates to reproduce the observed classification has been established using discriminant analysis. The central region of the wine surface gives the best results having lower measurement errors and higher classification performance. For white wines a*, b* and h _ab are the relevant colour coordinates scoring 84.8% of correctly classified samples. In rosé wines L*, a* and h _ab in the central region correctly classify 100% of the samples. This study demonstrates that colour of white and rosé wines can be measured in the same conditions that are found in the visual colour assessment when precise information on the visual colour appearance of wines is required.     

Exploring 2-aminoacetophenone contents in sparkling wines based on analytical data and statistical modelling

The influence of the second fermentation step on sparkling wine aroma was investigated with respect to the content of 2-aminoacetophenone (AAP) as an indicator substance for the atypical ageing off-flavour (ATA). AAP contents of aged sparkling wines and their corresponding base wines (Riesling and Chardonnay variety) were determined by means of multidimensional gas chromatography using a stable isotope dilution assay. The majority of sparkling wines were lower in AAP in comparison with their corresponding base wines. Explorative and predictive statistical analyses of the resulting AAP content in sparkling wines were performed concerning the influence of the parameters lees contact time, yeast strain, base wine AAP concentration and total phenolic contents. Both statistical approaches yielded good fits with AAP concentration of the base wine being the predominant factor. Although it was possible to explain the changes in AAP concentrations on the basis of how total phenolics changed during second fermentation, predicted AAP trends did not hinge upon the amount of total phenolics present in a base wine. Unpressurised model fermentations were a promising technological alternative to study the development of AAP in sparkling wines. Altogether, this study presents a multidisciplinary approach to master the challenging task of ATA risk assessment in base wines, which at present rather accesses the sparkling wine producer’s individual experience.     

Mousy off-flavour production in grape juice and wine by Dekkera and Brettanomyces yeasts

The ability of four known species of Dekkera and Brettanomyces yeasts to produce mousy off-flavour in grape juice and wine was investigated for the first time. Using a sensory assessment technique the twelve type strains of Dekkera and Brettanomyces , representing four species, were found to grow and to be capable of producing mousy off-flavour in a grape juice medium; however, differences between strains were apparent. Four strains representing the two species of Dekkera (D. bruxellensis and D. anomala ) known to be associated with the spoilage of wine and other fermented beverages were further investigated for mousy off-flavour production in a red and white wine supplemented with nutrients. D. anomala and only one of the three D. bruxellensis strains tested grew in both wines and generally produced a moderate level of off-flavour, whereas the remaining two strains of D. bruxellensis , despite slowly losing viability (10- to 100-fold) over the 52–55 day period, produced detectable off-flavour. This work demonstrates the general ability of Dekkera and Brettanomyces yeasts to produce mousy off-flavour and confirms the importance of these yeasts for off-flavour production in grape juice and wine.     

Occurrence of ochratoxin A (OTA) in wines: influence of the type of wine and its geographical origin.

The results of more than 450 samples taken from the literature and 400 samples tested by our own investigations have been taken into account to quite extensively describe the situation of OTA contamination of wine. According to these data OTA is much more commonly detected in red wines than in rosé and white wines and the OTA concentration is remarkably higher than in the last two. Thus OTA could be detected in 25% of white wine samples whereas it was detected in 40% of rosé and 54% of red wine samples. The same result was found when comparing the wines from southern and northern regions. Here the red wine samples from the northern cultivating area showed a contamination of 12% in contrast to those from the southern area which showed a contamination of about 95%.     

Short- and long-term efficiency of carboxymethylcellulose (CMC) to prevent crystal formation in South African wine

Crystal formation in bottled wine occurs due to the over-saturation of wine with potassium bitartrate (KHT) salt when exposed to low temperatures. In this study, special focus was given to the efficiency of a crystallisation-inhibiting additive, carboxymethylcellulose (CMC), which is widely used in the food industry. In 2008, CMC was authorised by the International Organisation of Vine and Wine (OIV) for use in white and sparkling wines, but is not yet officially permitted in all wine-producing countries. The use of CMC could be of economical importance to the wine industry because energy costs due to cooling can be reduced. Unlike traditional cooling methods, the use of CMC theoretically prevents the loss of acidity. In this study, the short- and long-term efficiencies of CMC were investigated in South African white, rosé and red wines. Efficiency was determined primarily by measuring changes in potassium (K⁺) and tartaric acid (H₂T) concentrations and visual crystal formation. As part of this study CMC's efficiency was compared with several other crystal inhibition treatments, and was also evaluated for its temperature stability over a year. CMC's effect on colour and total phenols was also assessed. The results reveal a high efficiency in preventing losses in K⁺ and H₂T concentrations in white wines, even with an ageing period of up to 12 months. The addition of CMC to rosé wines also delivered certain positive results, but less so for red wine. Three different commercial CMCs were also compared with mannoproteins to prevent changes in K⁺ and H₂T concentrations in three different wines. Furthermore, sensory evaluation was performed to determine certain organoleptic changes as a result of CMC treatments.     

An assessment of the effects of wine volatiles on the perception of taste and astringency in wine

The objective of this work is measuring the effect of different volatile extract compositions on the perception of taste, astringency, global intensity and persistence of wine. Six Spanish wines, two from Chardonnay and four from Tempranillo grapes, all of them showing different chemical and sensory characteristics, were selected. Wines were separated into volatile and non-volatile fractions by solid phase extraction and lyophilisation and further liquid extraction, respectively. Eighteen “reconstituted wines” were prepared, combining different volatile extracts and different non-volatile matrices and adjusting ethanol content to 12% (v/v), and were further described by a specifically trained sensory panel. Taste attributes (sweetness, acidity, bitterness), astringency, aroma intensity, global intensity and persistence were assessed in both, original and “reconstituted” wines by using a numerical category scale. The sensory properties of the original wines were retained by their corresponding “reconstituted samples”. The sensory assessment of the “reconstituted wines” showed that the addition of volatile fruity extracts from white wines brought about a decrease in astringency and bitterness and an increase in sweet perception in all cases. While global intensity and persistence of white wine matrices were also increased, they did not change in red wine matrices, which suggests that the volatile fraction plays only a secondary role in these attributes of red wines. Similarly, the effects of replacing the volatile fraction of a red wine by volatile extracts from other red wines were small and inconsistent, which confirms that taste and astringency are primarily driven by non-volatile molecules in these wines.     

Effect of the Closure Type on the Evolution of the Physical‐Chemical and Sensory Characteristics of a Montepulciano d'Abruzzo Rosé Wine

The present work studied the effect of the kind of closure (a screw cap, a natural cork, and 2 synthetic closures) on the evolution of the oxygen content and on the physical‐chemical and sensory characteristics of a Montepulciano d'Abruzzo rosé wine during the 1st 12 mo of bottle aging. The chemical analyses concerned the parameters more involved in the oxidative reactions (SO₂, acetaldehyde, phenols, wine color), as well as the main fermentative volatile compounds. The kind of closure influenced the oxygen content in wines, free and total SO₂ concentration, and wine color (color intensity and hue). During bottle aging, free and total SO₂ concentration was significantly and negatively correlated with absorbance at 420 nm (A420), whereas the correlations with A520 were weak. Probably, the limited extent of the variations in red color (A520), when varying SO₂ concentration, were due to the low pH of this rosé wine. No effect of the kind of closure on phenols and the main fermentative volatile compounds was observed. The wines bottled with cork closures (N trials), after 12 mo of storage, had higher color intensity and hue, measured by spectrophotometry, and were visually distinguished from the other trials for the more intense pink reflections. On the whole, under the conditions of this work, all the used closures guaranteed a good preservability to the rosè wines during the 1st year of bottle aging, and the changes in composition did not significantly affect wine sensory characteristics. Therefore, these synthetic closures can represent an alternative to the cork closures for a medium to long term bottle aging of these wines.     

Alcohol,Tannins, and Mannoprotein and their Interactions Influence the Sensory Properties of Selected Commercial Merlot Wines: A Preliminary Study

The objective of this study was to assess the influence of the interaction among alcohol, tannins, and mannoproteins on the aroma, flavor, taste, and mouthfeel characteristics of selected commercial Merlot wines. Merlot wines (n = 61) were characterized for wine chemistry parameters, including pH, titratable acidity, alcohol, glucose, fructose, tannin profile, total proteins, and mannoprotein content. Agglomerative clustering of these physicochemical characteristics revealed 6 groups of wines. Two wines were selected from each group (n = 12) and profiled by a trained sensory evaluation panel. One wine from each group was evaluated using the electronic tongue (e‐tongue). Sensory evaluation results showed complex effects among tannins, alcohol, and mannoproteins on the perception of most aromas, flavors, tastes, and mouthfeel attributes (P < 0.05). The e‐tongue showed distinct differences among the taste attributes of the 6 groups of wines as indicated by a high discrimination index (DI = 95). Strong correlations (r² > 0.930) were reported between the e‐tongue and sensory perception of sweet, sour, bitter, burning, astringent, and metallic. This study showed that interactions among wine matrix components influence the resulting sensory perceptions. The strong correlation between the e‐tongue and trained panel evaluations indicated the e‐tongue can complement sensory evaluations to improve wine quality assessment.