Organic Acids In Wine Research Articles

1H-NMR Spectroscopy Coupled with Chemometrics to Classify Wines According to Different Grape Varieties and Different Terroirs

In this study, 1H-NMR spectroscopy coupled with chemometrics was applied to study the wine metabolome and to classify wines according to different grape varieties and different terroirs. By obtaining the metabolomic fingerprinting and profiling of the wines, it was possible to assess the metabolic biomarkers leading the classification (i.e., phenolic compounds, aroma compounds, amino acids, and organic acids). Moreover, information about the influence of the soil in shaping wine metabolome was obtained. For instance, the relationship between the soil texture and the content of amino acids and organic acids in wines was highlighted. The analysis conducted in this study allowed extraction of relevant spectral information not only from the most populated and concentrated spectral areas (e.g., aliphatic and carbinolic areas), but also from crowded spectral areas held by lowly concentrated compounds (i.e., polyphenols). This may be due to a successful combination between the parameters used for data reduction, preprocessing and elaboration. The metabolomic fingerprinting also allowed exploration of the H-bonds network inside the wines, which affects both gustatory and olfactory perceptions, by modulating the way how solutes interact with the human sensory receptors. These findings may have important implications in the context of food traceability and quality control, providing information about the chemical composition and biomolecular markers from a holistic point of view.

High-performance bioelectronic tongue for the simultaneous analysis of phenols, sugars and organic acids in wines.

Electronic tongues have been widely used to analyze wines. However, due to the complexity of the matrix, the problem is not completely solved and further improvements are required. A high-performance potentiometric bio-electronic tongue (bio-ET) specifically devoted to the assessment of wine components is presented. The novelty of this system is due to two innovative approaches. First, the improved performance is obtained through the use of potentiometric biosensors based on carboxylated PVC membranes where enzymes specific to compounds of interest (glucose oxidase, tyrosinase, laccase and lyase) are linked covalently. Secondly, the performance is further enhanced by introducing in the PVC membrane electron mediators (AuNPs or CuPc) that facilitate the electron transfer process. Individual sensors exposed to target analytes (glucose, catechol, cysteine or tartaric acid) show a linear behavior with limits of detection in the range of 10-4 M for all the compounds analyzed, with excellent reproducibility (CV lower than 3%). Sensors combined to form a bio-ET, show excellent capabilities. Principal Component Analysis (PCA), can discriminate monovarietal white wines (PC1 77%; PC2 15%) and red wines (PC1 63%; PC2 30%). Using Partial Least Squares (PLS) the bio-ET can provide information about chemical parameters including Glucose, Total Polyphenols, Total Anthocyanins, Free SO2 , Total SO2 , Total acidity and pH with square correlation coefficients (R2 ) between 0.91 and 0.98 in calibration and between 0.89 and 0.98 in validation. This advanced instrument is able to assess the levels of seven parameters in a single measurement providing an advantageous method to the wine industry. This article is protected by copyright. All rights reserved.

The research on the composition of organic acids in young wines “Primeur” and “Virgin” with in C.V. “Ccricova” S.A.

This research concluded in getting experimental data about the composition of organic acids in wines obtained from varieties Cabernet-Sauvignon, Merlot, Pinot Noir, Rara Neagra, Feteasca Neagra, Shiraz (Syrah) produced within C.V. ”Cricova” S.A between 2015–2019 years. Also, it was argued the need to apply the malolactic fermentation simultaneously with alcoholic fermentation in order to increase the quality of young dry red wines, which allows the launch of the finished product in a restricted period of time. The degradation of malic acid in wine was achieved by malolactic fermentation bacteria, removing the excessive fresh taste of young wines ”Primeur” and ”Virgin”.

Rapid and Simple Method for Determination of Target Organic Acids in Wine Using HPLC-DAD Analysis

A high-performance liquid chromatography method coupled to diode array detector (HPLC-DAD) was validated and applied for determination of targeted organic acids (tartaric, malic, shikimic, lactic, citric, and succinic) in Chardonnay and Merlot wines. Simple sample preparation was carried out, including only wine dilution with water and filtration before injection to the HPLC system. Separation of the analytes was performed with isocratic elution on a Shimadzu Shim-pack GIST C18 column (250 mm × 4 mm I.D., 5 μm particle size) with a mobile phase, an aqueous solution of H3PO4, with a concentration of 5·10−3 mol/L at pH 2.1 and flow rate of 1 mL/min. Monitoring of the acids was performed at 210 nm wavelength. The method provides values for the linearity (R2 > 0.998), limits of detection (0.00002 to 0.0025 g/L) and quantification (0.00006 to 0.0085 g/L), precision (RSD < 10%), accuracy (recovery range 94.8–108%), repeatability (RSD values 2.53 to 7.19% for white wine and 1.96 to 9. 5% for red wine), and reproducibility (RSD values 2.08 to 12.69% for white wine and 5.21 to 14.77% for red wine). All validation parameters are considered acceptable in characterization of organic acids in wine. The results obtained for the samples studied showed similar content of organic acids to those found for wines from other regions of the world. Principal component analysis (PCA) was applied to verify the applicability of the quality control of the wines and resulted in the correct separation of the samples according to the variety.

Quantification of the Organic Acids in Hawthorn Wine: A Comparison of Two HPLC Methods

Hawthorn wine is rich in anthocyanins, polyphenols, flavonoids and other macromolecular substances, which results in difficulty to rapidly determine organic acids in the wine. An enzymatic method is accurate but expensive and not able to quantify all of the organic acids simultaneously. Therefore, in this study, two HPLC methods were applied to quantify the organic acids in the wine with the enzymatic method as a reference. Seven organic acids were found with the enzymatic method including citric, succinic, l-malic, acetic, lactic, pyruvic, and fumaric acids, in which citric and succinic acid accounted for more than 80% of the total acids. By an 87H column equipped with DAD (diode array) detector at 215 nm (HPLC method 1), only citric and lactic acids were quantified accurately and the elution period was shortened from 100 min to 20 min by removing the impurity in the sample with a LC-18 SPE(solid-phase extraction) tube. While citric, succinic, l-malic, acetic, pyruvic, and fumaric acids were quantified reliably by a dC18 column equipped with DAD detector at 210 nm (HPLC method 2), with the sample requires only dilution and filtration before injection. It was suggested that HPLC method 2 was an effective method to quantify the organic acids in hawthorn wine. The method provides a choice for accurate quantification of organic acids in hawthorn wine or other drinks, and would be helpful for controlling the quality of hawthorn wine.

Organic Acid Metabolism and the Impact of Fermentation Practices on Wine Acidity: A Review

The conversion of grape sugar to ethanol and carbon dioxide is the primary biochemical reaction in alcoholic wine fermentation, but microbial interactions, as well as complex secondary metabolic reactions, are equally relevant in terms of the composition of the final wine produced. The chemical composition of a wine determines the taste, flavour and aroma of the product, and is determined by many factors such as grape variety, geographical and viticultural conditions, microbial ecology of the grapes and of the fermentation processes, and the winemaking practices. Through the years, major advances have been made in understanding the biochemistry, ecology, physiology and molecular biology of the various yeast strains involved in wine production, and how these yeasts affect wine chemistry and wine sensory properties. However, many important aspects of the impact of yeast on specific wine-relevant sensory parameters remain little understood. One of these areas of limited knowledge is the contribution of individual wine yeast strains to the total organic acid profile of wine. Wine quality is indeed very directly linked to what wine tasters frequently refer to as the sugar–acid balance. The total acidity of a wine is therefore of prime sensory importance, and acidity adjustments are a frequent and legal practice in many wineries. However, the total acidity is the result of the sum of all the individual organic acids that are present in wine. Importantly, each of these acids has its own sensory attributes, with descriptors ranging from fresh to sour to metallic. It is therefore important not only to consider total acidity, but also the contribution of each individual acid to the overall acid profile of the wine. This review will summarise the current knowledge about the origin, synthesis and analysis of organic acids in wine, as well as on the management of wine acidity.

Analysis and Identification of Major Organic Acids in Wine and Fruit Juices by Paper Chromatography

A simple and inexpensive paper chromatography experiment that separates and identifies major organic acids in wine and fruit juices has been developed for introductory organic undergraduate student...

Simultaneous analysis of sugars and organic acids in wine and grape juices by HPLC: Method validation and characterization of products from northeast Brazil

Organic acids and sugars are related to the chemical balance of wines and grape juices, besides exerting a strong influence on the taste balance and sensorial acceptance by consumers. The aim of this study was to validate a method for the simultaneous determination of sugars and organic acids in wines and grape juices by high-performance liquid chromatography (HPLC) with refractive index detection (RID) and diode array detection (DAD) and to characterize commercial products from northeast Brazil. The method provided values for linearity (R > 0.9982), precision (CV% < 1.4), recovery (76–106%) and limits of detection (0.003–0.044 g L−1) and quantification (0.008–0.199 g L−1) which are considered acceptable for application in the characterization of these types of matrices. Principal components analysis (PCA) was used to verify the applicability of the method in the quality control of the products and resulted in the correct separation of the samples according to their type of processing. The results obtained in the characterization of the samples studied showed high levels of glucose and fructose in grape juice and the organic acids content was similar to those found in products originating from other regions around the world.

Development of a quantitative method for organic acid in wine and beer using high performance liquid chromatography.

This study was conducted to compare the organic acid content in liquors (red wine, white wine, and beer) using three different high-performance liquid chromatography analysis methods. Post-column reaction methods (method 2 and 3) were found to be more promising than UV-detection method (method 1). Using method 2 (two columns), the analyzed red wine was found to contain 2,652.4 mg/L tartaric acid and 1,392.9 mg/L lactic acid but relatively lower amounts of malic acid (271.0 mg/L). Furthermore, tartaric acid (1,160.8-2,749.1 mg/L) and malic acid (470.2-3,107.9 mg/L) were the major components in white wine. Beers were analyzed using method 3 (one column). In the analyzed foreign beers, lactic acid (95.9-226.4 mg/L), malic acid (62.2-110.5 mg/L), acetic acid (93.5-183.8 mg/L), and succinic acid (37.0-56.2 mg/L) were detected. Similar to the foreign beers, the contents of succinic acid in the domestic beers were the lowest. The proposed methods could be useful for quantitative analysis of organic acids in wine and beer.

Malic Acid in Wine: Origin, Function and Metabolism during Vinification

The production of quality wines requires a judicious balance between the sugar, acid and flavour components of wine. L-Malic and tartaric acids are the most prominent organic acids in wine and play a crucial role in the winemaking process, including the organoleptic quality and the physical, biochemical and microbial stability of wine. Deacidification of grape must and wine is often required for the production of well-balanced wines. Malolactic fermentation induced by the addition of malolactic starter cultures, regarded as the preferred method for naturally reducing wine acidity, efficiently decreases the acidic taste of wine, improves the microbial stability and modifies to some extent the organoleptic character of wine. However, the recurrent phenomenon of delayed or sluggish malolactic fermentation often causes interruption of cellar operations, while the malolactic fermentation is not always compatible with certain styles of wine. Commercial wine yeast strains of Saccharomyces are generally unable to degrade L-malic acid effectively in grape must during alcoholic fermentation, with relatively minor modifications in total acidity during vinification. Functional expression of the malolactic pathway genes, i.e. the malate transporter (mae1) of Schizosaccharomyces pombe and the malolactic enzyme (mleA) from Oenococcus oeni in wine yeasts, has paved the way for the construction of malate-degrading strains of Saccharomyces for commercial winemaking.

Main Organic Acids in Rice Wine and Beer Determined by Capillary Electrophoresis with Indirect UV Detection Using 2, 4-Dihydroxybenzoic Acid as Chromophore

A rapid and sensitive analytical method for the determination of main organic acids in wines was developed by capillary electrophoresis (CE) with indirect UV detection. Separation parameters including the pH of electrolyte, chromophore, and its concentration were optimized. The results showed that the optimal electrolyte for the separation of organic acids consisted of 10 mmol L−1 2, 4-dihydroxybenzoic acid (DHBA) at pH 3.6 containing 0.4 mmol L−1 cetyltrimethlammonium bromide (CTAB). DHBA as chromphore was selected based on the close mobility to the analyte and relatively large molar extinction coefficient. The method showed good linearity with limits of detection (LOD), ranging from 0.5 to 7.5 mg L−1. The relative standard deviation (RSD) of interday precisions for the peak area and the migration time were less than 7.2 and 0.8 %, respectively. The recoveries of the analyte in Chinese rice wine sample were between 90.3 and 106.9 % with RSD ranging from 1.4 to 8.9 %. The method was successfully applied to the commercial rice wine and beer samples with dilution and filtration.

Various instrumental approaches for determination of organic acids in wines

Biosensors based on lactate oxidase, sarcosine oxidase and mixture of fumarase and sarcosine oxidase were used for monitoring of organic acids in wine samples. Additionally, tartaric acid was determined by modified colorimetric method based on formation of the vanadate-tartrate complex. The above mentioned methods were used for the analysis of 31 wine samples and obtained data were compared with the results from capillary electrophoresis as a basic standard method. This comparison showed a certain degree of correlation between biosensors and capillary electrophoresis. The provided information pointed to the potential uses of biosensors in the field of winemaking.

Quantitation of organic acids in wine and grapes by direct infusion electrospray ionization mass spectrometry

Several organic acids such as malic, tartaric and citric acids were directly quantitated in wines and grapes.

On-line electrodialytic matrix isolation for chromatographic determination of organic acids in wine

Chromatographic determination of organic acids is widely performed, but the matrix often calls for lengthy and elaborate sample preparation prior to actual analysis. Matrix components, e.g., proteins, non-ionics, lipids etc. are typically removed by a combination of centrifugation/filtration and solid phase extraction (SPE) that may include the use of ion-exchange media. Here we report the quantitative electrodialytic transfer of organic acids from complex samples to ultrapure water in seconds using cellulose membranes modified with N,N-dimethylaminoethyl methacrylate, which essentially eliminates the negative ζ-potential of a regenerated cellulose membrane surface. The transfer characteristics of the ion transfer device (ITD) were evaluated with linear carboxylic acids. While the ion transfer efficiencies may be affected by the acid dissociation constants, in most cases it is possible to achieve quantitative transfer under optimized device residence time (solution flow rate) and the applied voltage. In addition, the transfer efficiency was unaffected by the wide natural variation of pH represented in real samples. The approach was applied to organic acids in various samples, including red wine, considered to represent an especially difficult matrix. While quantitative transfer of the organic acids (as judged by agreement with standard pretreatment procedures involving SPE) was achieved, transfer of other matrix components was <5%. The processed samples could then be chromatographically analyzed in a straightforward manner. We used ion exclusion chromatography with direct UV detection; in treated samples; there was a dramatic reduction of the large early peaks observed compared to only 0.45μm membrane filtered samples.

Determination of Organic Acids in Wine and Spirit Drinks by Fourier Transform Infrared (FT-IR) Spectroscopy

This study outlines the use of FTIR with partial least square (PLS) method and data obtained from the reference method is used to establish a full calibration model for tartaric acid, malic acid, lactic acid, succinic acid, citric acid and acetic acid using all matrix. It was not possible to obtain only one calibration for all analysed samples, but in some cases individual calibrations for specific samples were needed. It was due to the different matrixes in the studies samples: 12-15% ethanol (wines), 30-40% ethanol (spirits). Due to this reason, a calibration model was developed for each acid in red and white wine, and acetic acid in spirit drinks. During validation, strong correlation with the reference values and great accuracy were demonstrated for the higher concentration range (&gt;0.6 g/L) in all acids while inferior result was obtained in low range (&lt;0.6 g/L). But good result was obtained in lower concentration level both in wine and spirits in acetic acid, which explains that calibration and validation of the FTIR spectrometry depends very strongly on the composition of the sample set and on the quality of the reference analysis. The correlations for organic acids could further be improved with a more complete well distribution data base and optimizing wavelengths. DOI: http://dx.doi.org/10.3126/jfstn.v7i0.10564 J. Food Sci. Technol. Nepal, Vol. 7 (36-43), 2012

The Regularities of Electrolytic Dissociation of Weak Dibasic and Tribasic Organic Wine Acids

The weak dibasic and tribasic organic acids in wine: tartaric, malic, citric and succinic acids are the important components having direct influence on various properties of wine. The regularities of electrolytic dissociation of these acids determine all their useful properties. With the aid of suggested by authors original method for analysis the complex equilibria of the processes of dissociation of weak multibasic organic acids the main dissociation parameters of tartaric, malic, citric and succinic acids in their dilute solutions: the values of usual and “partial” degrees of dissociation of all steps, the concentrations of all anions, hydrogen ions and undissociated acid molecules are determined. The concentration intervals of predominance of various charged and uncharged substances in dilute solutions of all above mentioned acids are also determined. The simple empirical equations for fast approximate calculation of the dissociation degrees and pH values are also suggested.

Identification of Organic Acids in Wine That Stimulate Mechanisms of Gastric Acid Secretion

Wine may cause stomach irritation due to its stimulatory effect on gastric acid secretion, although the mechanisms by which wine or components thereof activate pathways of gastric acid secretion are poorly understood. Gastric pH was measured with a noninvasive intragastric probe, demonstrating that administration of 125 mL of white or red wine to healthy volunteers stimulated gastric acid secretion more potently than the administration of equivalent amounts of ethanol. Between both beverages, red wine showed a clear trend for being more active in stimulating gastric acid secretion than white wine (p = 0.054). Quantification of the intracellular proton concentration in human gastric tumor cells (HGT-1), a well-established indicator of proton secretion and, in turn, stomach acid formation in vivo, confirmed the stronger effect of red wine as compared to white wine. RT-qPCR experiments on cells exposed to red wine also revealed a more pronounced effect than white wine on the fold change expression of genes associated with gastric acid secretion. Of the quantitatively abundant organic acids in wine, malic acid and succinic acid most actively stimulated proton secretion in vitro. However, addition of ethanol to individual organic acids attenuated the secretory effect of tartaric acid, but not that of the other organic acids. It was concluded that malic acid for white wine and succinic acid for red wine are key organic acids that contribute to gastric acid stimulation.

Direct determination of organic acids in wine and wine-derived products by Fourier transform infrared (FT-IR) spectroscopy and chemometric techniques

FT-IR with partial least squares (PLS) was used to establish a full calibration model for tartaric acid, malic acid, lactic acid, succinic acid, citric acid and acetic acid in wines, vinegars and spirits. Sample pre-treatment was not required except for filtering.The PLS method was employed and FT-IR spectra were correlated with the results from a reference HPLC method. In the validation with an independent set of samples, a strong correlation with the reference values was demonstrated for the highest concentration range (>0.6gL−1) in all acids but the correlation was much weaker in the lower range (<0.6gL−1).In the case of acetic acid, however, good results were obtained in the low concentration range for both red and white wine and for spirit drinks. This finding explains the fact that calibration and validation of the FT-IR spectroscopy method depends very strongly on the composition of the sample set and on the quality of the reference analysis.It was not possible to obtain a single calibration for all of the analysed samples and in some cases individual calibrations for specific samples were required. This situation was due to the different matrixes in the studied samples: 12–15% ethanol (wines), 30–40% ethanol (spirits) and 6–10% acetic acid (vinegars). As a result, a calibration model was developed for each acid in red and white wine, tartaric acid, acetic acid and total acidity in vinegar, and acetic acid in spirit drinks.

High performance liquid chromatography with on-line dual quantum cascade laser detection for the determination of carbohydrates, alcohols and organic acids in wine and grape juice

In the present study the simultaneous use of two quantum cascade lasers (QC-lasers) was investigated for the on-line detection in high performance liquid chromatography (HPLC). An optical set-up based on three gold mirrors and a ZnSe beam splitter was used to direct the emitted laser light trough a liquid flow cell with an optical path length of 52 μm onto a mercury-cadmium-telluride (MCT) detector. Using the separation of eight components of wine and grape juice as an example, on-line dual QC-laser detection in HPLC could be shown successfully for the first time.

Differentiation and identification of white wine varieties by using electropherogram fingerprints obtained with CE

This article reports a method for determining organic acids by CE in order to obtain a characteristic fingerprint with a view to classifying white wine samples with the aid of multivariate statistics. The proposed method was optimized for the determination of the most abundant organic acids in wine (viz. succinic, malic, tartaric, citric, acetic and lactic). The acids were separated in a running buffer consisting of 180 mM disodium hydrogen phosphate, 0.5 mM CTAB and 10% methanol, adjusted to pH 7.5. The applied voltage was 10 kV and the working temperature 25 degrees C. The precision of the method was assessed by replicate analysis of a wine sample; the resulting RSD was less than 5.2% in peak area and less than 1% in migration time for all organic acids. Calibration curves exhibited good linearity throughout the studied concentration range for all acids. Principal component analysis and linear discriminant analysis allowed accurate classification of wine samples with variable alcohol contents from their electrophoretic fingerprints. The discriminant potential of various electropherogram regions was examined. Based on the results, the proposed method is an effective choice for classifying wine samples.