Quantitative determination of 2-methoxy-3-isobutylpyrazine in red wines and grapes of Bordeaux using a stable isotope dilution assay.

Quantitative analysis of 2-methoxy-3-isobutylpyrazine (MIBP) in grapes and wines was developed, using a stable isotope dilution assay. This was applied to red grapes and wines from the Bordeaux region. The grapes and the wines of the 1995 and 1996 vintages came from the three most frequently used varieties of the region, Merlot, Cabernet Franc and Cabernet Sauvignon. The wines made from Cabernet Sauvignon grapes exhibited levels of MIBP (mean concentration, 12 ng l-1 for 1996 vintage and 13 ng l-1 for 1995 vintage) close to or higher than its odour threshold in wines (10 ng l-1) and slightly higher than the amounts found in the Merlot wines (mean concentration, 8 ng l-1 for 1996 vintage and 4 ng l-1 for 1995 vintage), especially those of the 1996 vintage. The variation in the levels of MIBP in grape samples and in their corresponding wines was monitored at four different stages towards the end of maturation. MIBP was present in all grapes and wines analysed, even in surmaturation. A linear trend was observed between grapes and wines of the three cultivars during maturation.     

Quantitative determination of free and hydrolytically liberated beta-damascenone in red grapes and wines using a stable isotope dilution assay.

Quantitative analysis of free and hydrolytically liberated beta-damascenone in grapes and wines was developed, using a stable isotope dilution assay. Free beta-damascenone was isolated from grapes and wines by diethyl ether-hexane (1:1, v/v) extraction and the precursor(s) (glycosidic, polyols) of beta-damascenone using Sep-Pak Plus C18 RP cartridges. Hydrolytically liberated beta-damascenone was generated by acid hydrolysis from the precursor(s) extract. Red wines from Bordeaux (Merlot, Cabernet Sauvignon and Cabernet Franc, 1995 and 1996 vintage), Burgundy (Pinot Noir, 1995 and 1996 vintage) regions and Grenache wines from Chateauneuf du Pape and C?tes du Rh?ne (1995 vintage) were analysed to quantify free beta-damascenone. The wines made from Grenache and Cabernet Sauvignon (1996 vintage) grapes presented the highest mean amounts of free beta-damascenone, 5.4 and 5.5 micrograms l-1, respectively. Merlot, Cabernet Sauvignon and Cabernet Franc grapes of Bordeaux (1996 vintage) and their corresponding wines were analysed for quantification of free and hydrolytically liberated beta-damascenone. The levels of hydrolytically liberated beta-damascenone in grapes could predict closely the levels of free beta-damascenone in the corresponding wines after one year of ageing, i.e., almost half the levels found for the grape samples. The influence of enzyme and heat treatment of Merlot wine samples on their beta-damascenone levels was studied. Heat treatment doubled the levels of this compound, but enzyme treatment generated, in the corresponding wines, half the levels of beta-damascenone found in the non-enzyme treated wines.     

Comparison on phenolic compounds and antioxidant properties of cabernet sauvignon and merlot wines from four wine grape-growing regions in china

The antioxidant activities in the Cabernet Sauvignon and Merlot wines from four wine grape-growing regions in China were measured by different analytical assays: 2,2-diphenyl-1-picrylhydrazyl (DPPH·), cupric reducing antioxidant capacity (CUPRAC), superoxide radical-scavenging activity (SRSA) and the contents of total phenols, total flavonoids, total flavanols and total anthocyanins were determined. The results showed that the contents of phenolic compounds and the levels of antioxidant activity in the wine samples greatly varied with cultivar and environmental factors of vine growth. The contents of phenolic compounds and antioxidant activities in Cabernet Sauvignon and Merlot wines from the Yuquanying region of Ningxia were significantly higher than other three regions, followed by the wines from Shacheng region of Hebei, and these parameters were the lowest in Cabernet Sauvignon and Merlot wines from the Changli regions of Hebei and Xiangning region of Shanxi. Taken together, a close relationship between phenolic subclasses and antioxidant activity was observed for the wine samples. Moreover, there were significant discrepancies in the individual phenolic composition and content of four regional Cabernet Sauvignon and Merlot wines, among which the individual phenolic compounds (catechin, epicatechin, cinnamic acid, quercetin-3-O-glucuronide, quercetin-3-O-glucoside, laricitrin-3-O-glucoside and isorhamnetin-3-O-glucoside) revealed a significant correlation (p < 0.05) with the antioxidant capacity in present study, especially for catechin and epicatechin.     

Aroma composition of red wines by different extraction methods and Gas Chromatography-SIM/MASS spectrometry analysis

One hundred and one volatile compounds, reported in literature as powerful odorants of wine, were quantified by Gas Chromatography-Selective Ion Monitoring/Mass Spectrometry (GC-SIM/MS) in Primitivo, Aglianico, Merlot and Cabernet Sauvignon red wines. Wine samples were extracted by 3 different extraction methods: 1) separation of the alcoholic fraction from the aqueous phase by salting-out and subsequent extraction by liquid-liquid micro-extraction with 1,1,2-trichlorotrifluoroethane (Freon 113); 2) extraction by liquid-liquid micro-extraction with dichloromethane; 3) solid phase extraction (SPE cartridge: 800 mg of LiChrolut EN resin) with pentane-dichloromethane (20:1) and dichloromethane. The selection of the ion fragments used for quantification was directly performed on a red wine sample. For each compound the area of the corresponding peak was normalized respect to the peak of the internal standard and then interpolated in a calibration curve obtained analysing a model wine solution (water, ethanol, tartaric acid and known amounts of analytes and of internal standard). The methods showed a good linearity: r2>0.990, except for farnesol (isomer a and c), octanal, decanal, furaneol and phenylacetic acid with 0.966 < or = r2 < or = 0.990. The 7 most powerful odorants were: beta-damascenone, acetaldehyde, maltol, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, 3-methylbutanoic acid and acetal; 7 other slightly less important were: ethyl hexanoate, ethyl acetate, 1-octen-3-ol, butanoic acid, rose oxide, furaneol and sotolon. The Aglianico wines were characterised by the major fermentation compounds (esters, fatty acids and 2-phenylethanol), beta-damascenone, beta-ionone and linalool. The Primitivo wines were characterized by furaneol, methoxypyrazine, gamma-nonalactone and acetaldehyde, while Cabernet Sauvignon and Merlot wines principally by cask derivates (vanillin, (Z) 3-methyl-gamma-octalactone [(Z) wiskylactone], maltol and eugenol), some aldehydes and 3-isopropyl-2-methoxypyrazine.     

Use of multiple headspace solid-phase microextraction and pervaporation for the determination of off-flavours in wine

The occurrence of off-flavours in wines and especially the so-called "cork taint defect" represents one of the most serious problem in wine industry in which 2,4,6-trichloroanisole has been blamed as the main responsible. The development of analytical methods for haloanisoles determination in wine/cork represent a challenge, mainly due to food matrix complexity and low taste and odour (T&O) threshold levels which are generally beyond the sensitivity of the analytical systems. In this work, a method based on the combined use of the recently developed multiple headspace solid-phase microextraction (MHS-SPME) and gas chromatography-ion-trap mass spectrometry has been optimised for the determination of haloanisoles in wines. This powerful analytical methodology is compared with several analytical approaches based on pervaporation, an innovative membrane-based technique similar to dynamic headspace. Analytical features of the methods assayed reveal their suitability for the appraisal of haloanisoles in this matrix in which threshold odor concentrations are in the range 4-40 ng l(-1). The analytical approaches have been applied to the analysis of haloanisoles in different Spanish white and red wines, in which spiking experiments showed good recoveries for the methodologies assayed.     

Geographical classification of some Australian wines by discriminant analysis using HPLC with UV and chemiluminescence detection

HPLC with UV and acidified potassium permanganate chemiluminescence detection, combined with multivariate data analysis techniques, were used for the geographical classification of some Australian red (Cabernet Sauvignon) and white (Chardonnay) wines from two regions (Coonawarra and Geelong). Identification of the wine constituents prominent in the chromatography was performed by mass spectrometry. Principal components analysis and linear discriminant analysis were used to classify the wines according to region of production. Separation between regions was achieved with both detection systems and key components leading to discrimination of the wines were identified. Using two principal components, linear discriminant analysis with UV detection correctly classified 100% of the Chardonnay wines and, overall 91% of the Cabernet Sauvignon wines. With acidified potassium permanganate chemiluminescence detection, 75% of the Chardonnay wines and 94% of the Cabernet Sauvignon wines were correctly classified using two factors.     

Varietal discrimination of Australian wines by means of mid-infrared spectroscopy and multivariate analysis

This study outlines the use of mid-infrared (MIR) spectroscopy combined with principal component analysis (PCA) and linear discriminant analysis (LDA) for the varietal classification of commercial red and white table wines. Three red varieties (Cabernet Sauvignon, Shiraz and Merlot) and four white varieties (Chardonnay, Riesling, Sauvignon Blanc and Viognier) were sourced from different wine regions in Australia. Wine samples were scanned in transmission on a FOSS WineScan FT 120 from wave numbers 926 to 5012 cm⁻¹. All samples were sourced from the 2006 vintage and had not been blended with any other variety or wine from other regions. Spectral data were reduced to a small number of principal components (PCs) and LDA was then performed to successfully separate the wines into the different varieties. To test the robustness of the LDA models developed for the red wines, a set of red wines scanned in 2005 were used. Correct classification of over 95% was achieved for the validation set.     

Growth Parameter and Viability Modifications of Escherichia coli by Phenolic Compounds and Argentine Wine Extracts

The anti-bacterial effect of pure non-flavonoids gallic, vanillic, protocatechuic, and caffeic acids and flavonoids quercetin, rutin, and catechin and the effect of total polyphenols of three Argentinean wine varieties, Cabernet Sauvignon, Malbec, and Merlot, against Escherichia coli, microorganism frequently detected in fresh and processed foods, was investigated. The hydroxycinnamic derivate caffeic acid and the flavonoid quercetin were the more effective against E. coli. The polyphenol effect was ethanol independent. The E. coli decimal reduction times were 2.9, 2.1, and 0.65 h for Malbec wine and 2.8, 2.3, and 0.64 h for Merlot wine with respect to 1x, 2x, and 4x concentrated wine samples, respectively. For Cabernet Sauvignon wine, the values were 6.3, 3.7, and 1.28 h for 1x, 2x, and 4x concentrated samples, respectively. With clarified wines, the decimal reduction times were higher with values ranging from 15 to 18.4 h in the wine samples. So the phenolic compounds present in red wines could be considered as an interesting alternative to be used as natural preservative against pathogenic microorganisms.     

中国不同产区赤霞珠干红葡萄酒香气成分数据的可视化分析

可视化技术被引入葡萄酒香气成分数据的分析,以达到鉴别区分不同产区葡萄酒的目的。葡萄酒分析样品是2005年赤霞珠干红葡萄酒产品。5个产区是河北昌黎、新疆玛纳斯、云南弥勒、宁夏贺兰山东麓和河北沙城。香气成分用二氯甲烷连续萃取,有机相真空浓缩之后进行GC-MS分析检测。共鉴定并半定量分析出5个产区赤霞珠干红葡萄酒中68种香气成分,对原始色谱分析数据进行标准归一化处理,将信息映射到[0,1]之间的灰度图空间,然后根据数据可视化原理,用Vc 构建含多种香气成分信息的二维灰度图,直观表征不同产地赤霞珠干红葡萄酒的香气成分信息。研究结果是一种反映葡萄酒化学信息的条形码技术,该技术转换葡萄酒香气成分色谱数据之后得到二维灰度图,能够良好区分不同产区的赤霞珠干红葡萄酒。     

Determination of ochratoxin A in wine by means of immunoaffinity column clean-up and high-performance liquid chromatography

A new and accurate method to quantify ochratoxin A (OA) in table wine has been developed. The method uses commercial immunoaffinity columns for clean-up and high-performance liquid chromatography (HPLC) with fluorescence detection for quantification of the toxin. Wine was diluted with a solution containing 1% polyethylene glycol (PEG 8000) and 5% sodium hydrogencarbonate, filtered and applied to an OchraTest immunoaffinity column. The column was washed with a solution containing sodium chloride (2.5%) and sodium hydrogencarbonate (0.5%) followed by water. OA was eluted with methanol and quantified by reversed-phase HPLC with fluorometric detection (excitation wavelength 333 nm, emission wavelength 460 nm) using acetonitrile-water-acetic acid (99:99:2) as mobile phase. Average recoveries of OA from white, rosé and red wine samples spiked at levels from 0.04 to 10 ng/ml ranged from 88% to 103%, with relative standard deviations (RSDs) between 0.2 and 9.7%. Detection limit was 0.01 ng/ml based on a signal-to-noise ratio of 3:1. The method was applied successfully to 56 samples of red (38), rosé (8), white (9) and dessert (1) wine. The levels of OA ranged from <0.01 to 7.6 ng/ml with red wines more contaminated than rosé and white wines. A good correlation (r=0.987) was found by comparative analysis of 20 naturally contaminated samples using this method and the method of Zimmerli and Dick with better recoveries of OA and better performances for the new method. Several advantages of this method with respect to the actually available methods have been pointed out, with particular reference to red wine which appears to be the most difficult to analyze.     

Determination of 2,4,6-trichloroanisole and 2,4,6-tribromoanisole on ng L-1 to pgL-1 levels in wine by solid-phase microextraction and gas chromatography-high-resolution mass spectrometry

A gas chromatography-high-resolution mass spectrometry (GC-HRMS) method using solid-phase microextraction (SPME) for the determination of 2,4,6-trichloroanisole (TCA) and 2,4,6-tribromoanisole (TBA) in wine at low ng L(-1) levels was developed. A robust SPME method was developed by optimizing several different parameters, including type of fiber, salt addition, sample volume, extraction and desorption time. The quantification limit for TCA and TBA in wine was lowered substantially using GC-HRMS in combination with the optimized SPME method and allowed the detection of low analyte concentrations (ng L(-1)) with good accuracy. Limits of quantification for red wine of 0.3 ng L(-1) for TCA and 0.2 ng L(-1) for TBA with gas chromatography-negative chemical ionization mass spectrometry and 0.03 ng L(-1) for TCA and TBA were achieved using GC-HRMS. The method was applied to 30 wines of which 4 wines were sensorically qualified as cork defected. TCA was found in three of these wines with concentrations in the range 2-25 ng L(-1). TBA was not detected in any of the samples.     

Chemometrics on Microchips: Towards the Classification of Wines

The coupling of a capillary electrophoresis (CE) microchip with electrochemical detection with a chemometric approach was used for the classification of wines. Cabernet Sauvignon wine samples from 3 different geographical regions were used for verifying the discriminating power of the microchip electrophoretic technique using high separation voltage (3000 V) with analysis time of only 60 seconds. Electrophoretic data were transformed into initial 14 variables, concerning peak's area and peak's height. Principal component analysis was applied to optimize the information given by the electrophoretic data sets. Results of classification using LDA and CART were promising and the preliminary model was able to classify samples on the basis of their geographical origin. While the coupling of microchips with chemometrics approaches is illustrated for a former tentative of the classification of wines it could be readily extended to a wide range of other important applications.     

Occurrence of ochratoxin A in Turkish wines

A total of 95 wine samples including 34 white, 10 rosé and 51 red wines originating from four different Turkish areas were analysed for ochratoxin A (OTA). An analytical method based on immunoaffinity column (IAC) for clean-up and high performance liquid chromatography with fluorescence detection (HPLC-FD) was used to determine OTA in wines. The limit of detection (LOD) was estimated as 0.006 ng ml^− 1 for white wine and 0.010 ng ml^− 1 for rosé and red wines. The limit of quantification (LOQ) was estimated as 0.020 ng ml^− 1 in white wine and 0.030 ng ml^− 1 in rosé and red wines. Recovery experiments were carried out with spiked samples in the range 0.1–1 ng ml^− 1 of OTA. The average OTA recoveries from spiked white wine samples varied from 79.43% to 85.07%; while the mean recoveries for rosé and red wine samples were in the range of 77.48–83.96% and 76.61–83.55%, respectively. OTA was detected in 82 (86%) wine samples at levels of < 0.006–0.815 ng ml^− 1, which were below the maximum allowable limit established by the European Community. The mean OTA concentration in red wines was slightly higher than in white and rosé wines. Furthermore, our data indicate that the geographic region of origin has strong influence on OTA level for white, rosé and red wines: wines originating from Thrace (n = 44, mean = 0.158 ng ml^− 1) and Aegean (n = 28, mean = 0.060 ng ml^− 1) regions of Turkey were more contaminated with OTA compared with wines originating from central (n = 15, mean = 0.027 ng ml⁻¹) and east Anatolia (n = 8, mean = 0.027 ng ml^− 1) areas. This study showed that the occurrence of OTA in Turkish wines is high, but at levels that probably leads to a non-significant human exposure to OTA by consumption of wines.     

Exposure assessment to ochratoxin A from the consumption of Italian and Hungarian wines

A total of 267 wine samples including 19 dessert, 186 red, 11 rosé and 51 white produced mostly in the years 1997–2002 in Italian and Hungarian regions were analyzed for ochratoxin A (OTA) using inmunoaffinity column (IAC) clean-up and HPLC with fluorimetric detection. None of Hungarian wine samples were contaminated with this mycotoxin. For Italian red wines, 84% of the samples were positive for OTA ranged from 0.01 to 4.00 ng/mL. Furthermore, OTA was detected in 63% of dessert, in 56% of rosé and in 19% of white wine samples ranged from 0.01 to 1.64, from 0.01 to 1.04 and from 0.01 to 0.21 ng/mL, respectively. A study of OTA daily exposure assessment in Italian wines was also carried out outlining a quite low contribution to the overall daily intake.     

Determination of reactions between free radicals and selected Chilean wines and transition metals by ESR and UV-vis technique

Four different types of Chilean wines (Cabernet Sauvignon, Merlot, Carmenere and Syrah) were selected and examined in their free radical scavenging capacities by electron spin resonance (ESR) and spectrophotometric methods. The free radical scavenging properties were evaluated against 2,2-diphenyl-1-picrylhydrazyl (DPPH*) radical, 2,6-di-tert-butyl-alpha-(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadien-1-ylidene)-p-tolyloxy (Galvinoxyl) radical and hydroxyl radical (HO*). The possible effect on these scavenging properties of added transition metals to these wines was evaluated. Among the wines evaluated, Cabernet Sauvignon was the one with the highest activity against all radicals tested. The presence of added copper or iron to wines resulted in a reduced free radical scavenging capacity for all type of wines studied. The formation of redox inactive complexes between polyphenols of wine and transition metals is the possible cause of this reduction in antioxidant activity.     

Development of a mixed-mode solid phase extraction method and further gas chromatography mass spectrometry for the analysis of 3-alkyl-2-methoxypyrazines in wine

A new method for analysing 3-isopropyl-2-methoxypyrazine, 3-sec-butyl-2-methoxypyrazine and 3-isobutyl-2-methoxypyrazine in wine has been developed and applied to wine. The analytes are extracted from 25 mL of wine in a solid-phase extraction cartridge filled with 60 mg of cation-exchange mixed-mode sorbent. Analytes are recovered with triethylamine in dichloromethane and the organic extract is analysed by GC-SIM-MS using 3-isopropyl-2-ethoxypyrazine as internal standard. The detection limits of the method are in all cases under 1 ng/L, below the olfactory thresholds of the compounds in wine. The repeatability of the method is around 15% for levels in wine of 2 ng/L. Linearity is satisfactory and recoveries are in all cases close to 100% with RSD between 13% and 20%. The method has been applied to the analysis of 12 Chilean white and 8 Spanish red wines. The levels found suggest that 3-alkyl-2-methoxypyrazines can exert a significant sensory contribution to the aroma of Chilean Sauvignon Blanc wines, while most likely they play a nearly negligible role on traditional Ribera and Rioja Spanish red wines.     

Determination of the biogenic amines in musts and wines before and after malolactic fermentation using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate as the derivatizing agent

An accurate, rapid and sensitive high-performance liquid chromatographic (HPLC) method is reported for the determination of four biogenic amines in red and white wine samples. The method involves derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) followed by liquid chromatography gradient elution analysis without any other sample pretreatment. The procedure developed permitted the determination of the four amines in 40 min. The relative standard deviation (RSD) values ranged from 3.1% to 6.1% in peak areas and the response was linear (R2>0.994) in a range from 0.1 to 4 mg/l. Leaving aside putrescine in Tempranillo wines, the malolactic fermentation did not exert any effect on the concentration of these compounds. On the contrary, the influence of the grape variety was important, and Tempranillo wines showed higher levels of tyramine and histamine and lesser of putrescine and cadaverine (p<0.05) than wines made with Cabernet Sauvignon.     

Influence of different bentonites on the rare earth element concentrations of clarified Romanian wines

The rare earth element (REE) concentrations of 19 Romanian young wine samples originating from the Dealurile Moldovei viticulture area were determined by double focusing inductively coupled plasma mass spectrometry (DF-ICP-MS) after microwave-assisted digestion with nitric acid. The determination of Eu was hampered by the BaO molecular interference. Generally, the red wine samples were more concentrated for REEs than the white wine samples studied. The REE concentrations of the four bentonites (Gelbenton, Evergel, BW200, Tükrös) determined after their fusion were higher by three orders of magnitude than those of the wine samples. After a simulated wine purification process performed with these bentonite samples and a red and white pool samples, the REE concentrations of the clarified wine samples increased by 1.2–1.5 times for red, and 1.3–3 times for white wines in case of the fibrous bentonite sample (Gelbenton), by about 2–5 times in case of the bentonite containing ovalbumin, caseine and gelatine (Evergel), meanwhile this factor was about 20–25 for Na bentonite powder samples (BW200, Tükrös). On basis of the chemometric evaluation using the REE concentrations as input data, the majority of the Feteasca wines belonged to the same cluster as well as the two Cabernet Sauvignon to another subcluster. The adequate choice of the bentonite may allow the use of REEs as fingerprints for determining the wine provenance.     

Determination of flavone C-glucosides in antioxidant of bamboo leaves (AOB) fortified foods by reversed-phase high-performance liquid chromatography with ultraviolet diode array detection

A sensitive solid-phase microextraction and gas chromatography-pulsed flame photometric detection technique was developed to quantify volatile sulfur compounds in wine. Eleven sulfur compounds, including hydrogen sulfide, methanethiol, ethanethiol, dimethyl sulfide, diethyl sulfide, methyl thioacetate, dimethyl disulfide, ethyl thioacetate, diethyl disulfide, dimethyl trisulfide and methionol, can be quantified simultaneously by employing three internal standards. Calibration curves were established in a synthetic wine, and linear correlation coefficients (R2) were greater than 0.99 for all target compounds. The quantification limits for most volatile sulfur compounds were 0.5 ppb or lower, except for methionol which had a detection limit of 60 ppb. The recovery was studied in synthetic wine as well as Pinot noir, Cabernet Sauvignon, Pinot Grigio, and Chardonnay wines. Although the sulfur compounds behaved differently depending on the wine matrix, recoveries of greater than 80% were achieved for all sulfur compounds. This technique was applied to analyze volatile sulfur compounds in several commercial wine samples; methionol concentrations were found at the ppm level, while the concentrations for hydrogen sulfide, methanethiol, and methyl thioacetate were at ppb levels. Only trace amounts of disulfides and trisulfides were detected, and ethanethiol was not detected.