White Wine Samples Research Articles

Matrix assisted laser desorption ionization mass spectrometry linear time-of-flight method for white wine fingerprinting and classification

A fast and simple method for white wine differentiation based on fingerprinting by means of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) combined with linear time-of-flight (TOF) mass spectrometry (MS) and statistical interpretation of the obtained data using principal component as well as cluster analysis is presented. A systematic development was performed to allow a direct comparison and classification of 33 Croatian white wines based on MALDI linear TOF mass spectra (“assuming protein/peptide fingerprints”) in the positive ion mode. α-Cyano-4-hydroxycinnamic acid as a MALDI matrix in solution mixed with the unmodified (without any dilution or preconcentration or purification/isolation) white wine sample in a volume ratio 1:1 was applied at ambient conditions and this volume sample preparation technique provided the highest mass spectral information content and optimal reproducibility. Several MALDI matrices, solvents and preparation techniques were evaluated with the selection of the above mentioned as the optimum, prior to large scale investigations. Data obtained by statistical analysis of the aligned mass spectrometric data are shown to provide an efficient way to differentiate white wines of Croatian origin.

Development of an indirect enzyme immunoassay for the determination of thiabendazole in white and red wines

A competitive indirect enzyme immunoassay for the determination of fungicide thiabendazole in white and red wine samples was developed. The assay had a detection limit of 0.005 ng mL−1, a dynamic range from 0.01 to 2 ng mL−1, and was precise with intra- and inter-assay coefficient of variation values less than 5% and 8%, respectively. Concerning the sample preparation procedure, it was found that filtration of the wine samples through a 0.45 μm pore size polytetrafluoroethylene (PTFE) filter followed by 30 times dilution with the assay buffer eliminated completely matrix interferences for both white and red wines derived from different grape varieties. This was demonstrated by the accurate determination of thiabendazole amounts in spiked wine samples (% recovery 90.6–108). In addition, the results obtained for certain spiked wine samples were in good agreement with those received by an LC-MS/MS method for determination of thiabendazole in wines. Taking into account the dilution factor, the thiabendazole concentrations that could be determined in wines ranged from 0.3 to 60 ng mL−1. The maximum residue limit (MRL) of thiabendazole in wine grapes is 50 μg kg−1. Thus, the proposed enzyme immunoassay can be applied for the fast and parallel analysis of a high number of white and red wine samples with minimal sample pre-treatment.

Effect of Bentonite Characteristics on Wine Proteins, Polyphenols, and Metals under Conditions of Different pH

Studies have yet to evaluate how bentonite properties may affect the protein profile, polyphenol content, metal concentration, and heat stability of a white wine at different pH values. Therefore, this work assessed the proteins, polyphenols, metals, and haze forming tendency when heating white wine samples before and after a fining treatment with four activated sodium bentonites in a typical wine pH range (3.00 to 3.60). Soluble wine proteins were separated by sodium dodecyl sulfate - polyacrylamide gel electrophoresis, and gel images were compared using the Quantity One software package (Bio-Rad Laboratories, Inc., Hercules, CA). The wine haze forming tendency, metals, and polyphenols were measured using heat tests and International Organisation of Vine and Wine (OIV) methods. Low molecular mass proteins were efficiently removed by all of the bentonites, regardless of the pH. High and medium molecular mass proteins were less likely to be removed and the efficiency, which depended on the pH, was variable. Reductions of vacuolar invertase (GIN1) and VVTL1 fractions of the thaumatin-like proteins were induced by bentonites with pH values less than 10. These bentonites were affected to a lesser extent by the negative effect of acidic pH. The reduction in haze forming tendency of the unfined Erbaluce wine was particularly noticeable in bentonite fined samples heated at 50 to 60°C, 60 to 80°C, and 70 to 80°C at pH 3.17, pH 3.30, and pH 3.60, respectively. The poor removal of glycoproteins (YGP1 and Hmp1) at higher pH values contributed to an increased thermal stability. The exchange of cationic species, notably sodium and potassium, between the bentonites and the wine was related more to the wine pH than to the clay type. Finally, the extent of polyphenol removal correlated with the amount of protein removed. When protein removal did not occur, the reduction of polyphenols was driven by the specific surface area and the surface charge density of the bentonite.

Identification of Catechin, Syringic Acid, and Procyanidin B2 in Wine as Stimulants of Gastric Acid Secretion.

Organic acids of wine, in addition to ethanol, have been identified as stimulants of gastric acid secretion. This study characterized the influence of other wine compounds, particularly phenolic compounds, on proton secretion. Forty wine parameters were determined in four red wines and six white wines, including the contents of organic acids and phenolic compounds. The secretory activity of the wines was determined in a gastric cell culture model (HGT-1 cells) by means of a pH-sensitive fluorescent dye. Red wines stimulated proton secretion more than white wines. Lactic acid and the phenolic compounds syringic acid, catechin, and procyanidin B2 stimulated proton secretion and correlated with the pro-secretory effect of the wines. Addition of the phenolic compounds to the least active white wine sample enhanced its proton secretory effect by 65 ± 21% (p < 0.05). These results indicate that not only malic and lactic acid but also bitter and astringent tasting phenolic compounds in wine contribute to its stimulatory effect on gastric acid secretion.

An electrochemical sensor for gallic acid based on Fe₂O₃/electro-reduced graphene oxide composite: Estimation for the antioxidant capacity index of wines.

A highly sensitive electrochemical sensor for gallic acid (GA), an important polyphenolic compound, was fabricated using the hybrid material of chitosan (CS), fishbone-shaped Fe2O3 (fFe2O3), and electrochemically reduced graphene oxide (ERGO) as the sensing matrix. The electrochemical characterization experiments showed that the CS-fFe2O3-ERGO modified glassy carbon electrode (CS-fFe2O3-ERGO/GCE) had large surface area, excellent electronic conductivity and high stability. The GA presented a superior electrochemical response on CS-fFe2O3-ERGO/GCE in comparison with the single-component modified electrode. The electrochemical mechanism and optimal test conditions of GA on the electrode surface were carefully investigated. Under the optimal conditions, the oxidation peak currents in differential pulse voltammetry (DPV) experiments exhibited a good linear relationship with the logarithmic values of GA concentration over the range from 1.0×10(-6)M to 1.0×10(-4)M. Based on signal-to-noise (S/N) characteristic of 3, the detection limit was estimated to be 1.5×10(-7)M. The proposed sensor has also been applied for estimating the antioxidant capacity index of real samples of red and white wines.

Colorimetric Sensor Array for White Wine Tasting.

A colorimetric sensor array was developed to characterize and quantify the taste of white wines. A charge-coupled device (CCD) camera captured images of the sensor array from 23 different white wine samples, and the change in the R, G, B color components from the control were analyzed by principal component analysis. Additionally, high performance liquid chromatography (HPLC) was used to analyze the chemical components of each wine sample responsible for its taste. A two-dimensional score plot was created with 23 data points. It revealed clusters created from the same type of grape, and trends of sweetness, sourness, and astringency were mapped. An artificial neural network model was developed to predict the degree of sweetness, sourness, and astringency of the white wines. The coefficients of determination (R2) for the HPLC results and the sweetness, sourness, and astringency were 0.96, 0.95, and 0.83, respectively. This research could provide a simple and low-cost but sensitive taste prediction system, and, by helping consumer selection, will be able to have a positive effect on the wine industry.

Label-free impedimetric aptasensor for ochratoxin-A detection using iridium oxide nanoparticles.

In this article, a novel aptasensor for ochratoxin A (OTA) detection based on a screen-printed carbon electrode (SPCE) modified with polythionine (PTH) and iridium oxide nanoparticles (IrO2 NPs) is presented. The electrotransducer surface is modified with an electropolymerized film of PTH followed by the assembly of IrO2 NPs on which the aminated aptamer selective to OTA is exchanged with the citrate ions surrounding IrO2 NPs via electrostatic interactions with the same surface. Electrochemical impedance spectroscopy (EIS) in the presence of the [Fe(CN)6](-3/-4) redox probe is employed to characterize each step in the aptasensor assay and also for label-free detection of OTA in a range between 0.01 and 100 nM, obtaining one of the lowest limits of detection reported so far for label-free impedimetric detection of OTA (14 pM; 5.65 ng/kg). The reported system also exhibits a high reproducibility, a good performance with a white wine sample, and an excellent specificity against another toxin present in such sample.

Classification of monovarietal Argentinean white wines by their elemental profile

The possibility of acquire a chemometric model to classify Argentinean white wines according to their provenance through elemental profile was assessed. A simple method for multielement determination in wines by inductively coupled plasma mass spectrometry along with chemometric pattern-recognition techniques is proposed. A total of 57 white wine samples of the main varieties from four winegrowing regions of Argentina: Mendoza, Rio Negro, San Juan, and Salta, were evaluated. The results of principal component analysis explained 95.95% of the variance data total. Linear discriminant analysis allowed correct discrimination according to the four geographical regions evaluated, using only five ultratrace elements (Ba, As, Pb, Mo, and Co). Discrimination rates higher than 96% for prediction and validation data sets were reached. The outcomes emphasize the skillfulness of ICPMS elemental determination in combination with chemometrics, for classification of white wine and show that could be a trustworthy technique to validate the geographical origin, authenticity and quality control of wines.

Feasibility of dispersive liquid–liquid microextraction for extraction and preconcentration of Cu and Fe in red and white wine and determination by flame atomic absorption spectrometry

A method for extraction and preconcentration of Cu and Fe in red and white wines using dispersive liquid–liquid microextraction (DLLME) and determination by flame atomic absorption spectrometry (F AAS) was developed. Extraction was performed using sodium diethyldithiocarbamate as chelating agent and a mixture of 40μL of 1,2-dichlorobenzene (extraction solvent) and 900μL of methanol (dispersive solvent). Some parameters that influencing the extraction efficiency such as pH (2 to 5), concentration of chelating agent (0 to 2%), effect of salt addition (0 to 10%), number of washing steps (1 to 4) and centrifugation time (0 to 15min) were studied. Accuracy was evaluated after microwave-assisted digestion in closed vessels and analytes were determined by inductively coupled plasma optical emission spectrometry. Agreement with the proposed method ranged from 91 to 110 and from 89 to 113% for Cu and Fe, respectively. Calibration of F AAS instrument was performed using analyte addition method and limits of detection were 6.3 and 2.4μgL−1 for Cu and Fe, respectively. The proposed method was applied for the determination of Cu and Fe in five samples of red wine and three samples of white wine, with concentration ranging from 21 to 178μgL−1 and from 1.38 to 3.74mgL−1, respectively.

Straightforward method to quantify GSH, GSSG, GRP, and hydroxycinnamic acids in wines by UPLC-MRM-MS.

A novel, robust and fast ultrahigh performance liquid chromatography–multiple reaction monitoring mass spectrometry method has been developed for the simultaneous quantification of reduced glutathione (GSH), oxidized glutathione (GSSG), grape reaction product (GRP) and hydroxycinnamic acids in wine. The method was evaluated in terms of linearity, precision, accuracy, limits of detection and quantification, stability and matrix effects. Quantitative recovery (74–110%) and satisfactory interday precision (RSD <14%) were achieved for all target compounds. No significant matrix-dependent suppression/enhancement effects were observed. To demonstrate the method applicability, white, rosé and red wine samples with different levels of oxidation were analyzed. Levels of GSH and GSSG varied from 1.63 to 9.91 mg/L and from 0.32 to 3.33 mg/L, respectively. Levels of caftaric acid ranged from 2.57 to 293.07 mg/L. Levels of GRP were between 28.35 and 114.20 mg/L.

Effects of Beverage Ingredients on Salivary Fluid Secretion with an &amp;lt;i&amp;gt;ex Vivo&amp;lt;/i&amp;gt; Submandibular Gland Perfusion System: Tannic Acid as a Key Component for the Inhibition of Saliva Secretion

Tannic acid (TA) and TA containing beverage have been proved to inhibit Ca2+-activated Cl- channel located apical membrane of the secretory cells. However, their effect on salivary fluid secretion is not well investigated. We used mouse ex Vivo submandibular gland perfusion technique to identify the general effect of TA and related beverage samples on muscarinic agonist carbachol induced fluid secretion. Green tea inhibited fluid secretion by 64% from the control, where oolong tea was by 53%, and red wine by 43% which was linked with their TA concentration. On the other hand, though TA was contained at 4.7 μM in white wine sample and 33 μM in coffee extract, no adverse effect was observed. In addition, coffee induced salivation in the absence of carbachol. TA had a negative effect on fluid secretion with a concentration dependent manner. The effects of TA on carbachol induced calcium increase showed identical as fluid secretion, which was initially no effect, and then gradually decreased over the time. These results demonstrate that TA directly inhibits the salivary fluid secretion and it affects not only Ca2+-activated Cl- channel but also intracellular Ca2+ increasing mechanisms.

Biosensor for Aluminum(III) Based on α-Chymotrypsin Inhibition using a Disposable Screen-Printed Carbon Electrode and Acetyl-Tyrosine Ethyl Ester as Substrate

We report on a new amperometric assay for Al(III) ions based on the inhibition of α-chymotrypsin enzyme. The immobilization of the enzyme was performed on screen-printed carbon electrodes modified with gold nanoparticles and polyvinyl alcohol. N-acetyl-tyrosine ethyl ester, used as enzyme substrate, produces an oxidation amperometric signal, which at increasing aluminum concentration is diminished. The developed system has a detection limit of 1.5 ± 0.1 μM (n=7) for Al(III). The reproducibility of the method is 6.6% (n=5) and its repeatability is 8.2% (n=3). Main interferences at low concentration, include As(V), Cd(II), and Mo(VI) ions. The developed method was successfully applied to the determination of Al(III) in spiked white wine sample. Results agree with the certified value giving a value of percent recovery of 103 ± 4% (n=4).

Determination of boron in Turkish wines by microwave plasma atomic emission spectrometry

Boron in various Turkish red wine and white wine samples was determined by microwave plasma-atomic emission spectrometry (MP-AES) at 249.677 nm. MP-AES is a novel instrument which provides a low-cost analysis based on a micro-wave plasma generated with nitrogen. Wine samples were not pre-treated prior to analysis. The recovery rate of boron added to the 1:1 diluted wine samples was around 80% which showed interference due to the matrix of the wine samples. Therefore standard addition method was used for quantifications. The limit of detection and limit of quantification were 0.08 and 0.28 μg mL−1, respectively. A satisfactory linearity (r2 > 0.999) was obtained up to 10 mg L−1 of boron. The range of boron concentrations in various wine samples was 4.2–10.8 mg L−1.

Determination of fluorine in Turkish wines by molecular absorbance of CaF using a high resolution continuum source atomic absorption spectrometer

Fluorine contents of different types of wines produced in Turkey were determined by the molecular absorption of calcium mono-fluoride (CaF) using a high resolution continuum source graphite furnace atomic absorption spectrometer (HR-CS GFAAS). For this purpose, 2000 μg mL−1 of calcium was co-injected to the graphite furnace with diluted wine samples. In order to increase the sensitivities and reduce the limit of detection (LOD) and characteristic mass, summation of the absorbances for CaF at 606.440 nm and 606.231 nm were evaluated. Graphite furnace program was optimized for best accuracy and 700 °C for pyrolysis, 2250 °C for molecule forming temperature was selected. Quantification was made by linear calibration, standard addition technique by HR-CS-AAS and the results were also compared with ISE method and no significant difference was found. The range of F contents for 20 red and white wine samples varies between LOD and 0.38 mg L−1. The limit of detection and characteristic mass of the method were 0.18 and 0.058 ng of F, respectively which are appropriate to detect the fluorine concentrations in most of the wine samples. The method is simple, fast, accurate and sensitive.

Application of electronic tongue to discriminate white wines originated from different regions of Hungary

In this work, the application of an electronic tongue (ET) based on a specific ion-selective sensor array for discrimination of different white wine types is presented. The electronic tongue equipped with specific sensor array containing seven IFSET sensors was used to analyze wine samples. The obtained ET responses were evaluated using different pattern recognition methods. Principal component analysis (PCA) provides the possibility to identify some initial patterns. Linear discriminant analysis (LDA) was used to build models to separate white wine samples based on wine regions and grape cultivars. The results showed that every group was distinguished from each other with no misclassification error. Furthermore, the sequence of the wine sample groups was similar to the increasing total acidity content. Partial least square (PLS) regression was used to build models for the prediction of the main chemical compositions of the wine samples based on the electronic tongue results. The closest correlation (R2=0.93) was found in case of ‘total acidity’, and the prediction error (RMSEP) was 6.9%. The pH of the wine samples was predicted with good correlation (R2=0.89) but higher prediction error (RMSEP=10.71%) from the electronic tongue results. The ET combining these statistical methods can be applied to determine the origin and variety of the wine samples in easy and quick way.

Fluorescent carbon nanodots for sensitive and selective detection of tannic acid in wines

Herein we describe an easy one step synthesis of carbon nanodots (C-dots) by thermal carbonization of 6-bromohexylboronic acid using two different amine compounds, polyethyleneglycol bis(3-aminopropyl (PEGA) and 1,2-aminopropane (DPA), at 180°C in atmospheric oxygen. The as-synthesized C-dots were characterized by FTIR, HRTEM, NMR and fluorescence. The C-dots prepared using PEGA showed a strong emission at 440nm with excitation at 362nm. These C-dots exhibited analytical potential as sensing probes for tannic acid (TA) determination. pH effect, interferences, and analytical performance of the method were investigated. The method was found effective in the linear concentration range from 0.1 to 10mgL−1 TA achieving a limit of detection equal 0.018mgL−1 TA. The applicability of the method was demonstrated by direct measurements of TA in red and white wine samples. Validation of the method was achieved by spiking the wine samples with different standard TA concentrations obtaining recoveries in the range (90–112.5%). A probable mechanism by which TA quenched the C-dots fluorescence was proposed.

Dinuclear copper(II) octaazamacrocyclic complex in a PVC coated GCE and graphite as a voltammetric sensor for determination of gallic acid and antioxidant capacity of wine samples

A novel efficient differential pulse voltammetric (DPV) method for determination gallic acid (GA) was developed by using an electrochemical sensor based on [Cu2tpmc](ClO4)4 immobilized in PVC matrix and coated on graphite (CGE) or classy carbon rod (CGCE). The proposed method is based on the gallic acid oxidation process at formed [Cu2tpmcGA]3+ complex at the electrode surface. The complexation was explored by molecular modeling and DFT calculations. Voltammograms for both sensors, recorded in a HNO3 as a supporting electrolyte at pH 2 and measured in 2.5×10−7 to 1.0×10−4M of GA, resulted with two linear calibration curves (for higher and lower GA concentration range). The detection limit at CGE was 1.48×10−7M, while at CGCE was 4.6×10−6M. CGE was successfully applied for the determination of the antioxidant capacity based on GA equivalents for white, rosé and red wine samples.

Analysis of phenolics in wine by high performance thin-layer chromatography with gradient elution and high resolution plate imaging

Health benefits of wine, especially with red wine, have been linked to the presence of a wide range of phenolic antioxidants. Thus, the aim of this study was to develop a simple, high performance thin layer chromatographic (HPTLC) method combined with high resolution digital plate images to visually compare multiple wine samples simultaneously on a single chromatographic plate and to quantify levels of gallic acid, caffeic acid, resveratrol and rutin, as representatives of the four different classes of phenolics found in wines. We also wanted to investigate the contribution of the investigated phenolic compounds to the total polyphenolic content (TPC) and total antioxidant capacity (TAC) of the wine samples.The average concentrations of caffeic acid, gallic acid, resveratrol, and rutin in the red wines were 2.15, 30.17, 0.59 and 2.47mg/L respectively with their concentration below limit of quantification in the white wine samples. The highest concentration of resveratrol and rutin is found in the Cabernet and Shiraz wine samples. The amounts of gallic acid are correlated with TPC (r=0.58). Italian wines have the highest correlation between TPC and TAC (r=0.99) although they do not contain detectable amounts of resveratrol, they contain significant amount of rutin. Therefore, antioxidant properties might be associated with the presence of flavanols in these wines.

Malate quinone oxidoreductase biosensors based on tetrathiafulvalene and gold nanoparticles modified screen-printed carbon electrodes for malic acid determination in wine

Screen-printed carbon electrodes have been modified with gold nanoparticles, tetrathiafulvalene and malate quinone oxidoreductase enzyme for the sensitive and selective detection of malic acid. Amperometric experimental conditions were optimized taking into account the importance of quantifying malic acid in wine samples and the inherent complexity of these samples, particularly red wine. The biosensor responds to malic acid giving an anodic current (at +100mV and pH 6.5) in a wide concentration range, with a capability of detection of 2.0μM (α=β=0.05) at room temperature. The method has been applied to the determination of malic acid in white, rose and red wine samples, with averages recoveries of 99.6%.

Single-Run Separation and Determination of Aliphatic and Aromatic Carboxylic Acids in Wine and Human Urine Samples by Ion-Exclusion Chromatography

This work is focused on developing a new chromatographic method with UV detection for the separation and determination of thirty-two carboxylic aliphatic and/or aromatic acids in a single run. Ion-exclusion chromatography with a silica based, modified with C18, analytical column Alltech Prevail™ organic acid 5 µm (150 mm × 4.6 mm I.D) was used for the solving of this problem. The developed method was based on ion-exclusion and/or hydrophobic interaction chromatographic separation mechanism. The effect of the concentrations of phosphate buffer and its pH as well as the column temperatures on the retention of the test acids has been investigated. Gradient elution of the mobile phase composed of aqueous phosphate buffer and methanol was used to achieve a required separation of carboxylic acids within 45 min. All measurements were done at 220 nm. Column temperature was set at 25 ± 0.1 °C. The LOD values for organic acids range from 0.002–2.224 mg L−1. The repeatability of the procedure developed is characterized by the RSD, which varied between 0.52 and 2.85 % for the peak area. The proposed method was successfully applied for the determination of aliphatic and aromatic acids in dry white wine and human urine samples.