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.     

The use of high performance liquid chromatography-quadrupole time-of-flight mass spectrometry coupled to advanced data mining and chemometric tools for discrimination and classification of red wines according to their variety

In this study, the potential of high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (HPLC–QTOFMS) for metabolomic profiling of red wine samples was examined. Fifty one wines representing three varieties (Cabernet Sauvignon, Merlot, and Pinot Noir) of various geographical origins were sourced from the European and US retail market. To find compounds detected in analyzed samples, an automated compound (feature) extraction algorithm was employed for processing background subtracted single MS data. Stepwise reduction of the data dimensionality was followed by principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) which were employed to explore the structure of the data and construct classification models. The validated PLS-DA model based on data recorded in positive ionization mode enabled correct classification of 96% of samples. Determination of molecular formula and tentative identification of marker compound was carried out using accurate mass measurement of full single MS spectra. Additional information was obtained by correlating the fragments obtained by MS/MS accurate mass spectra using the QTOF with collision induced dissociation (CID) of precursor ions.     

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.     

Usefulness of chemometrics and mass spectrometry-based electronic nose to classify Australian white wines by their varietal origin

A combination of mass spectrometry-based electronic nose (MS e_nose) and chemometrics was explored to classify two Australian white wines according to their varietal origin namely Riesling and unwooded Chardonnay. The MS e_nose data were analysed using principal components analysis (PCA), discriminant partial least squares (DPLS) and linear discriminant analysis (LDA) applied to principal components scores and validated using full cross validation (leave one out). DPLS gave the highest levels of correct classification for both varieties (>90%). LDA classified correctly 73% of unwooded Chardonnay and 82% of Riesling wines. Even though the conventional analysis provides fundamental information about the volatile compounds present in the wine, the MS e_nose method has a series of advantages over conventional analytical techniques due to simplicity of the sample-preparation and reduced time of analysis and might be considered as a more convenient choice for routine process control in an industrial environment. The work reported here is a feasibility study and requires further development with considerably more commercial samples of different varieties. Further studies are needed in order to improve the calibration specificity, accuracy and robustness, and to extend the discrimination to other wine varieties or blends.     

Prediction of phenolic compounds in red wine fermentations by visible and near infrared spectroscopy

Near infrared (NIR) spectroscopy was used to simultaneously predict the concentrations of malvidin-3-glucoside (M3G), pigmented polymers (PP) and tannins (T) in red wine. A total of 495 samples from 32 commercial scale red wine fermentations over two vintages using two grape varieties (Cabernet Sauvignon and Shiraz), and also including as additional variables two types of fermenters, two different yeasts, and three fermentation temperatures were used. Samples were scanned in transmission mode (400-2500 nm) using a monochromator instrument (NIRSystems6500). Calibration equations were developed from high performance liquid chromatography (HPLC) and NIR data using partial least squares (PLS) regression with internal cross validation. Using PLS regression, very good calibration statistics (R_cal²>0.80) were obtained for the prediction of M3G, PP and T with standard deviation (S.D.)/standard error in cross validation (SECV) ratio (residual predictive deviation, RPD)) ranging from 1.8 to 5.8. It was concluded that near infrared spectroscopy could be used as rapid alternative method for the prediction of the concentration of phenolic compounds in red wine fermentations.     

Direct coupling of a gas-liquid separator to an ion mobility spectrometer for the classification of different white wines using chemometrics tools

The potential of a vanguard technique as is the ion mobility spectrometry with ultraviolet ionization (UV-IMS) coupled to a continuous flow system (CFS) have been demonstrated in this work using a gas phase separator (GPS). This vanguard system (CFS-GPS-UV-IMS) has been used for the analysis of different types of white wines to obtain a characteristic profile for each type of wine and their posterior classification using different chemometric tools. Precision of the method was 3.1% expressed as relative standard deviation. A deep chemometric study was carried out for the classification of the four types of wines selected. The best classification performance was obtained by first reducing the data dimensionality by principal component analysis (PCA) followed by linear discriminant analysis (LDA) and finally using a k-nearest neighbour (kNN) classifier. The classification rate in an independent validation set was 92.0% classification rate value with confidence interval [89.0%, 95.0%] at 95% confidence level.The same white wines analyzed using CFS-GPS-UV-IMS were analyzed using gas chromatography with a flame detector (GC-FID) as conventional technique. The chromatographic method used for the determination of superior alcohols in wine samples shown in the Regulation CEE 1238/1992 was selected to carry out the analysis of the same samples set and later the classification using appropriate chemometrics tools. In this case, strategies PCA-LDA and kNN classifier were also used for the correct classification of the wine samples. This combination showed similar results to the ones obtained with the proposed method.     

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.     

Measurement uncertainty of shikimic acid in red wines produced in Chile

High-performance liquid chromatography (HPLC) to determine shikimic acid is used as a complementary tool to differentiate wine varieties. In order to correctly classify, measurement uncertainty of shikimic acid by HPLC in red wine was estimated considering the following components: uncertainty associated with the preparation of shikimic acid stock solution, uncertainty associated with quantification using a calibration curve, and uncertainty associated with precision. The most important contribution to total uncertainty was the method precision. The expanded uncertainty (U) for different wine varieties was between 2.6 and 8.5%. The method was applied to determine the concentration of shikimic acid in different emerging wine varieties cultivated in Chile, such as Carmenère, Shiraz, and Pinot Noir, comparing them with classical varieties, such as Cabernet Sauvignon and Merlot. Shiraz wines presented lower shikimic acid concentrations (between 27 and 86 mg L⁻¹ with U _(k=2) = 2.6%) than Cabernet Sauvignon wines (between 41 and 142 mg L⁻¹ with U _(k=2) = 8.1%), but their concentrations were higher than found in Merlot (from 9 to 41 mg L⁻¹ with U _(k=2) = 4.3%) and Carmenère wines (between 7 and 49 mg L⁻¹ with U _(k=2) = 5.8%). Pinot Noir was the variety with the lowest concentration of this acid (7–14 mg L⁻¹ with U _(k=2) = 8.5%). Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

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.     

Multi-Elemental Analysis of Wine Samples in Relation to Their Type,Origin, and Grape Variety

Wine is one of the most popular alcoholic beverages. Therefore, the control of the elemental composition is necessary throughout the entire production process from the grapes to the final product. The content of some elements in wine is very important from the organoleptic and nutritional points of view. Nowadays, wine studies have also been undertaken in order to perform wine categorization and/or to verify the authenticity of products. The main objective of this research was to evaluate the influence of the chosen factors (type of wine, producer, origin) on the levels of 28 elements in 180 wine samples. The concentration of studied elements was determined by ICP-MS (Ag, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, Pb, Rb, Sb, Sn, Sr, Te, Tl, U, Zn), ICP-OES (Ca, Fe, K, Mg, Ti), and CVAAS (Hg) techniques in 79 red, 75 white, and 26 rose wine samples. In general, red wines contained higher values of mean and median of B, Ba, Cr, Cu, Mn, Sr and Zn in contrast to other wine types (white and rose). In white wines (when compared to red and rose wines) higher levels of elements such as Ag, Be, Bi, Cd, Co, Li, K and Ti were determined. In contrast, rose wines were characterized by a higher concentration of Fe and U. The study also revealed that in the case of 18 samples, the maximum levels of some metals (Cd—8 samples, Pb—9 samples, Cu—1 sample) were slightly exceeded according to the OIV standards, while for Zn and Ti in any wine sample the measured concentrations of these metals were above the permissible levels. Thus, it can be stated that the studied wines contained, in general, lower levels of heavy metals, suggesting that they should have no effect on the safety of consumption. The results also showed higher pH level for red wines as a consequence of the second fermentation process which is typically carried out for this type of wine (malolactic fermentation). The highest median value of pH was reported for Merlot-based wines, while the lowest was for Riesling. It is assumed that dry Riesling has a higher content of tartaric and malic acid than dry Chardonnay grown in the same climate. From all of the studied countries, wines from Poland seemed to present one of the most characteristic elemental fingerprints since for many elements relatively low levels were recorded. Moreover, this study revealed that also wine samples from USA and Australia can be potentially discriminated from the rest of studied wines. For USA the most characteristic metal for positive identification of the country of origin seems to be uranium, whereases for Australia – strontium and manganese. Based on the highly reduced set of samples, it was not possible to differentiate the studied wine products according to the grape variety other than Syrah, and partially Chardonnay. Since all the Syrah-based samples originated from the same country (Australia) thus, the observed grouping should be more related with the country of origin than the grape variety.     

Nuclear Magnetic Resonance Metabolomics with Double Pulsed-Field-Gradient Echo and Automatized Solvent Suppression Spectroscopy for Multivariate Data Matrix Applied in Novel Wine and Juice Discriminant Analysis

The quality of foods has led researchers to use various analytical methods to determine the amounts of principal food constituents; some of them are the NMR techniques with a multivariate statistical analysis (NMR-MSA). The present work introduces a set of NMR-MSA novelties. First, the use of a double pulsed-field-gradient echo (DPFGE) experiment with a refocusing band-selective uniform response pure-phase selective pulse for the selective excitation of a 5–10-ppm range of wine samples reveals novel broad ¹H resonances. Second, an NMR-MSA foodomics approach to discriminate between wine samples produced from the same Cabernet Sauvignon variety fermented with different yeast strains proposed for large-scale alcohol reductions. Third a comparative study between a nonsupervised Principal Component Analysis (PCA), supervised standard partial (PLS-DA), and sparse (sPLS-DA) least squares discriminant analysis, as well as orthogonal projections to a latent structures discriminant analysis (OPLS-DA), for obtaining holistic fingerprints. The MSA discriminated between different Cabernet Sauvignon fermentation schemes and juice varieties (apple, apricot, and orange) or juice authentications (puree, nectar, concentrated, and commercial juice fruit drinks). The new pulse sequence DPFGE demonstrated an enhanced sensitivity in the aromatic zone of wine samples, allowing a better application of different unsupervised and supervised multivariate statistical analysis approaches.     

Characterization of Greek Wines by Ultraviolet–Visible Absorption Spectroscopy and Statistical Multivariate Methods

Optical absorption spectroscopy has been used to study Cretan Greek wine matured for 3 months in various barrels. Vilana and Dafni white and Kotsifali and Mandilari red wines were analyzed. The total phenolic index for all varieties and color characteristics for only the red wine were determined. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) demonstrated that the absorption spectra, combined with multivariate statistical methods, may be used to identify these varieties. The results of principal component analysis were used to infer the chemical compounds responsible for the discrimination between varieties.     

Classification of Wines Based on Different Antioxidant Responses to Spectrophotometric Analytical Methods

Six well established spectrophotometric assays (Folin-Ciocalteu, DPPH, ABTS^?+, FRAP, CUPRAC, and the o-diphenols method) have been complementary implemented in order to estimate the total phenolic and o-diphenolic content as well as the free radical scavenging and reducing antioxidant capacities of 40 white and 10 red wines of different varieties and geographic origin. In white wines, the results were weakly correlated; whereas, the results in red wines were strongly correlated, therefore, postulating their separate use in order to estimate efficiently the correlation between results of these methods. The results were subjected to the unsupervised PCA pattern recognition method to investigate the possible classification of white wines. PC analysis framed the wine samples in clear clusters, when the extracted PCA model was based on the results of all six spectrophotometric assays. The usefulness of implementing assays based on different antioxidant mechanisms is discussed. To our knowledge, this is the first time different responses of antioxidants to these spectrophotometric assays have been used to classify white wines according to their variety.     

Classification of Wines Based on Combination of ^1H NMR Spectroscopy and Principal Component Analysis

A combination of ^1H nuclear magnetic resonance （NMR） spectroscopy and principal component analysis （PCA） has shown the potential for being a useful method for classification of type, production origin or geographic origin of wines. In this preliminary study, twenty-one bottled wines were classified/separated for their location of production in Shacheng, Changli and Yantai, and the types of the blended, medium dry, dry white and dry red wines, using the NMR-PCA method. The wines were produced by three subsidiary companies of an enterprise according to the same national standard. The separation was believed to be mainly due to the fermentation process for different wines and environmental variations, such as local climate, soil, underground water, sunlight and rainfall. The major chemicals associated with the separation were identified.     

Development of a Wine Metabolomics Approach for the Authenticity Assessment of Selected Greek Red Wines

Wine metabolomics constitutes a powerful discipline towards wine authenticity assessment through the simultaneous exploration of multiple classes of compounds in the wine matrix. Over the last decades, wines from autochthonous Greek grape varieties have become increasingly popular among wine connoisseurs, attracting great interest for their authentication and chemical characterization. In this work, 46 red wine samples from Agiorgitiko and Xinomavro grape varieties were collected from wineries in two important winemaking regions of Greece during two consecutive vintages and analyzed using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QToF-MS). A targeted metabolomics methodology was developed, including the determination and quantification of 28 phenolic compounds from different classes (hydroxycinnamic acids, hydroxybenzoic acids, stilbenes and flavonoids). Moreover, 86 compounds were detected and tentatively identified via a robust suspect screening workflow using an in-house database of 420 wine related compounds. Supervised chemometric techniques were employed to build an accurate and robust model to discriminate between two varieties.     

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.     

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.     

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.     

Determination of histamine in port wines and grape juices by ion-pair extraction and stable isotope dilution GC-MS

Summary An isotope dilution, GC-MS method for the quantitation of histamine in wines and grape juices was assayed. This method includes isolation of histamine and its, deuterated analogue [α,α,β,β-²H₄]histamine, used as the labelled internal standard, by ion-pair extraction with bis-2-ethylhexylphosphate, conversion to the volatile derivative: tris-pentafluorobenzyl-histamine, capillary GC separation and measurement of the abundance ratio of the (M-181)⁺ ions from labelled and unlabelled derivatives. The method was successfully applied to the determination of histamine in several samples of Port wine, red and white table wine and grape juice. Data are given on detectability, linearity, repeatability and recovery.     

Quantitative determination of beta-ionone in red wines and grapes of Bordeaux using a stable isotope dilution assay.

Quantitative analysis of beta-ionone has been developed, using a stable isotope dilution assay. This was applied to red wines from different cultivars and regions. The Burgundy Pinot noir wines exhibited the highest levels of beta-ionone. The variation in the levels of beta-ionone in grape samples and in their corresponding wines, of Merlot, Cabernet Sauvignon and Cabernet franc from Bordeaux regions was monitored at four different stages towards the end of maturation: the levels of beta-ionone were almost similar, exhibiting only a slight decrease during maturation. beta-Ionone occurred in all the grapes and wines samples analysed at levels higher than, or close to its odour threshold which was determined in a model wine solution and was found to be of 90 ng l-1. In a previously supplemented model wine solution with beta-ionone (250 ng l-1), the odour threshold was found to be of 980 ng l-1 (total levels).