Acid In Wine Research Articles

Simultaneous Analysis of Organic Acids, Glycerol and Phenolic Acids in Wines Using Gas Chromatography-Mass Spectrometry.

Fermented beverages, particularly wines, exhibit variable concentrations of organic and phenolic acids, posing challenges in their accurate determination. Traditionally, enzymatic methods or chromatographic analyses, mainly high-performance liquid chromatography (HPLC), have been employed to quantify these compounds individually in the grape must or wine. However, chromatographic analyses face limitations due to the high sugar content in the grape must. Meanwhile, phenolic acids, found in higher quantities in red wines than in white wines, are typically analyzed using HPLC. This study presents a novel method for the quantification of organic acids (OAs), glycerol, and phenolic acids in grape musts and wines. The approach involves liquid-liquid extraction with ethyl acetate, followed by sample derivatization and analysis using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) detection mode. The results indicated successful detection and quantification of all analyzed compounds without the need for sample dilution. However, our results showed that the method of adding external standards was more suitable for quantifying wine compounds, owing to the matrix effect. Furthermore, this method is promising for quantifying other metabolites present in wines, depending on their extractability with ethyl acetate. Fermented beverages, particularly wines, exhibit variable concentrations of organic and phenolic acids, posing challenges in their accurate determination. Traditionally, enzymatic methods or chromatographic analyses, mainly high-performance liquid chromatography (HPLC), have been employed to quantify these compounds individually in the grape must or wine. The approach of this proposed method involves (i) methoximation of wine compounds in a basic medium, (ii) acidification with HCl, (iii) liquid-liquid extraction with ethyl acetate, and (iv) silyl derivatization to analyze samples with gas chromatography-mass spectrometry (GC-MS) in ion monitoring detection mode (SIM). The results indicated successful detection and quantification of all analyzed compounds without the need for sample dilution. However, our results showed that the method of adding external standards was more suitable for quantifying wine compounds, owing to the matrix effect. Furthermore, this method is promising for quantifying other metabolites present in wines, depending on their extractability with ethyl acetate. In other words, the proposed method may be suitable for profiling (targeted) or fingerprinting (untargeted) strategies to quantify wine metabolites or to classify wines according to the type of winemaking process, grape, or fermentation.

Dual-signal detection of tannic acid in red wines based on the peroxidase activity of carbon dots.

Herein, a novel type of phosphorus and iron-doped carbon dot (P,Fe-CD) with outstanding peroxidase activity and excellent fluorescence performance was hydrothermally synthesized to colorimetrically and fluorimetrically detect tannic acid (TA). In the presence of 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2, the P,Fe-CDs could oxidize colorless TMB to a blue oxidation product (oxTMB) resulting in an increased value of absorbance. Simultaneously, the fluorescence intensity of P,Fe-CDs at 430 nm could be quenched owing to the fluorescence resonance energy transfer (FRET) between P,Fe-CDs and the generated oxTMB. Meanwhile, after adding the TA to the system containing TMB, H2O2 and P,Fe-CDs, the value of absorbance could be decreased and the fluorescence could be recovered because of the reduction reaction between TA and oxTMB. Therefore, fluorescence intensity and value of absorbance could be applied to quantitatively detect TA with good linearities between the concentration of TA and the fluorescence intensity/value of absorbance (0.997 and 0.997 for the colorimetric signal and fluorimetric one, respectively) and low limits of detection (0.093 μmol L-1 and 0.053 μmol L-1 for the colorimetry and the fluorimetry, respectively), which was successfully applied to the detection of TA in red wines. Moreover, we applied a smartphone-assisted method to the point-of-care detection of TA with accurate results, providing a new technique for TA detection and food quality monitoring.

Adsorption properties and kinetics of organic acids in yellow rice wine by weakly basic anionic resins based on membrane separation

Abstract Yellow rice wine (Huangjiu) is a traditional alcoholic beverage in China. This study aimed to find a new method to reduce the acidity of Huangjiu. Three membranes with different molecular weight cut-offs (200, 1000, and 2000 Da) were selected to separate small molecules in Huangjiu, and then the adsorption of four models of weakly basic anion-exchange resins (335, D301, D314, and D354) on the organic acids in the filtered fractions of Huangjiu was investigated. The D354 resin exhibited the highest adsorption rate of 157.74 mg/g and the adsorption of acids was more consistent with the proposed second-order kinetic model. The adsorption capacity of D354 resin decreased with increasing temperature, and the adsorption of D354 resin correlated better with the Freundlich isotherm model. The initial deacidification efficiency of the D354 resin was 91.52% and it decreased by 3.88% after 10 regenerations. After the D354 resin treatment, the total acid content decreased by 56.11%, and the retention rates of amino acids and volatile substances reached 97.96% and 81.93%, respectively. The results showed that D354 resin could be used for the deacidification of Huangjiu. Membrane separation combined with resin adsorption process provides a new method to reduce the acidity of Huangjiu, which helps to maintain the flavor of the deacidified Huangjiu while efficiently reducing the acidity.

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.

Role of amino acids in flavor profiles and foam characteristics of sparkling wines during aging

As sparkling wine ages, a well-balanced amino acid composition can enrich its flavor profiles and achieve an optimal state for foam characteristics. This study aimed to determine the influence of amino acids on the flavor profiles and foam characteristics of white and rosé sparkling wine. The concentrations of amino acids and aroma compounds were determined via liquid chromatography–mass spectrometry (LC–MS) and gas chromatography-mass spectrometry (GC-MS), respectively. Correlation analysis and multiple linear regression (MLR) models were employed for further analysis. It revealed that the content of amino acids (except for proline) in both sparkling wines decreased with aging (11–23%). Ethyl octanoate had the largest odor activity value (OAV) value in both wines, but its content decreased with aging. The foam parameters of both sparkling wines decreased with increased aging duration, leading to changes in effervescence-related taste traits. Correlation analysis showed that most amino acids positively correlated with ethyl octanoate and foam characteristics, whereas the foam parameters did not increase along with the protein concentrations. Furthermore, the MLR analysis emphasized that amino acids had a greater impact on foam characteristics than volatiles. This study provides guidance for the production of high-quality sparkling wines.

Exploring Human Metabolome after Wine Intake-A Review.

Wine has a rich history dating back to 2200 BC, originally recognized for its medicinal properties. Today, with the aid of advanced technologies like metabolomics and sophisticated analytical techniques, we have gained remarkable insights into the molecular-level changes induced by wine consumption in the human organism. This review embarks on a comprehensive exploration of the alterations in human metabolome associated with wine consumption. A great number of 51 studies from the last 25 years were reviewed; these studies systematically investigated shifts in metabolic profiles within blood, urine, and feces samples, encompassing both short-term and long-term studies of the consumption of wine and wine derivatives. Significant metabolic alterations were observed in a wide variety of metabolites belonging to different compound classes, such as phenolic compounds, lipids, organic acids, and amino acids, among others. Within these classes, both endogenous metabolites as well as diet-related metabolites that exhibited up-regulation or down-regulation following wine consumption were included. The up-regulation of short-chain fatty acids and the down-regulation of sphingomyelins after wine intake, as well as the up-regulation of gut microbial fermentation metabolites like vanillic and syringic acid are some of the most important findings reported in the reviewed literature. Our results confirm the intact passage of certain wine compounds, such as tartaric acid and other wine acids, to the human organism. In an era where the health effects of wine consumption are of growing interest, this review offers a holistic perspective on the metabolic underpinnings of this centuries-old tradition.

Effect of pre-flowering gibberellic acid applications on tartaric acid content in grape berries

Tartaric acid (TA) is a characteristic acid in grapes (Vitis vinifera L.), capable of increasing the acidity of wine, providing a fresh and lively taste, and contributing to the stability of wine while reducing the risk of microbial contamination. However, the transcriptional regulatory mechanisms underlying TA synthesis remain not clear. Here, we found that gibberellic acid (GA3) treatment can increase the content of TA with the upregulation of TA synthesis-related gene, which was confirmed by RNA-seq results. Yeast one-hybrid and electrophoretic mobility shift assay (EMSA) validated that transcription factor VvbZIP60 can interact with the promoter of VvL-IdnDH and activate its expression to promote TA synthesis. In summary, exogenous application of GA3 can elongate fruit clusters, improve fruit quality, and especially increase the TA content in fruit. This study provides a theoretical basis for the purposeful regulation of fruit TA content in grape production.

СОДЕРЖАНИЕ ОРГАНИЧЕСКИХ КИСЛОТ СУСЛА И ВИНА ИЗ ВИНОГРАДА СОРТА ПЕРВЕНЕЦ МАГАРАЧА В ЗАВИСИМОСТИ ОТ ПРИМЕНЯЕМЫХ АГРОТЕХНИЧЕСКИХ ПРИЕМОВ

The influence of shoots load on the qualitative and quantitative composition of organic acids of musts and wines made from Pervenets Magara-cha grapes was studied. The research of influ-ence of agrotechnical measures was carried out on must and wine materials, on the following variants of experiment: load of 30 shoots / shrub; 35 shoots / shrub; 40 shoots / shrub; 45 shoots/shrub. It was revealed that the composi-tion of organic acids in grapes and wine to a greater extent depends on the varietal features of grapes and conditions of the year of harvest, while a clear dependence of the composition of organic acids on the load of bushes with shoots for the variety Pervenets Magaracha as a result of these studies could not be established.

Using abandoned unripe grape resources to solve the low-acid problem in the northwest wine region of China

Low acid is the main defect in the northwest wine region of China in recent years. The fermentation of unripe grape (UG) and wine grapes with low acid contents was carried out. Compared with control group (CK), the addition of UG addressed the core flaw that low acid grape bring to wine firstly, it significantly increased titratable acid, tartaric acid and malic acid while significantly decreasing alcohol and volatile acids in wine. Secondly, UG significantly improved wine color, the color parameters a*, b*, C* and L* were significantly increased to different degrees. At the same time, the addition of UG significantly improves other qualities of wine, including the phenolic substances and antioxidant capacity of wine. In addition, adding UGJ2% significantly improved the sensory quality, and pleasant volatile substances such as phenethyl alcohol, ethyl hexanoate, ethyl butyrate and isoamyl acetate were significantly increased, giving the wine more prominent floral and fruity aromas.

Preharvest salicylic acid application improves the amino acid content and volatile profile in Vitis vinifera L. cv. Chardonnay during development

Nitrogen is an important component that affects grapevine growth and the formation of flavor-associated volatile chemicals in grape berries. Dynamic changes in amino acids and aroma compounds in Chardonnay grape berry preharvest treated with different doses of salicylic acid (SA) at onset and one week later of veraison stage were evaluated. Exogenous 1- or 3-mM SA application significantly increased the content of total soluble solid and titratable acid in grapes, while 5 mM SA tended to decrease their levels. Compared with the control, the concentration of yeast assimilable nitrogen were 9.3% and 14.6% higher in 3 mM SA-treated grapes in 2021 and 2022, respectively. Preharvest 3 mM SA treatment efficiently enhanced the accumulation of nine amino acids, including tryptophan, phenylalanine, tyrosine, aspartic acid, lysine, asparagine, valine, isoleucine and histidine, as well as the concentration of total amino acid with and without proline in the two grape vintages. Higher concentrations of primary phenylalanine-derivatives and terpenoids and lower levels of C6 compounds in grapes treated with 3 mM SA were observed during the 2021–2022 season. Overall, SA improved the quality of wine grape in a dose dependent manner, while the response of berries to SA treatment also showed effects of the vintage.

Development and Validation of a New Method for Detecting Acetic Bacteria in Wine.

In winemaking, excessive production of acetic acid by acetic acid bacteria poses a major challenge, leading to rejection of wine by consumers. The aim of this study was to devise an economically viable and easy-to-use liquid culture medium for the preventive detection of microorganisms capable of generating acetic acid in wine. The modified medium incorporated specific nutrients that favored the growth of acetic acid bacteria and increased selectivity. Under varying conditions and with different types of wine, this medium was tested together with inoculated samples, comparing the occurrence of acetic acid and olfaction. The result was a new liquid medium based on olfactometry, designed to facilitate its use in wineries, even by untrained personnel and without the need for complex laboratory equipment. Validation was carried out on a variety of wines, determining the onset of the presence of acetic acid in the medium. This innovative culture medium provides a means to estimate the concentration of micro-organisms capable of producing acetic acid in wine. Its application in wineries facilitates proactive decision making, avoiding undesirable increases in acetic acid concentration.

<i>Agaricus bisporus</i> chitosan influences the concentrations of caftaric acid and furan-derived compounds in Pinot noir juice and base wine

Chitosan is a fining agent used in winemaking, although its use in juice and wine beyond fining has been limited until now. Therefore, this study's first aim was to determine if chitosan derived from Agaricus bisporus (button mushrooms) could reduce caffeic and caftaric acid concentrations in Pinot noir grape juice (Study A). The second aim was to determine if chitosan, when added to base wine, could influence the synthesis of furan-derived compounds during storage (Study B). In Study A, Pinot noir grape juice was stored at 10 °C for 18 hours after the following treatments: control (no addition), bentonite/activated charcoal (BAC), low molecular weight (< 3 kDa; LMW) chitosan, med. MW (250 kDa; MMW) chitosan, and high MW (422 kDa; HMW) chitosan (all 1 g/L additions). Caftaric acid was decreased, and total amino acid concentration was increased in the LMW chitosan-treated juice, while the estimated total hydroxycinnamic acid content, turbidity, and browning were decreased in the MMW chitosan-treated juice compared to the control. In Study B, Pinot noir base wine destined for sparkling wine was stored at 15 and 30 °C for 90 days with the following treatments: control (no addition), LMW chitosan, MMW chitosan, and HMW chitosan (all 1 g/L additions). The three chitosan treatments stored at 30 °C had increased furfural, homofuraneol, and 5-methylfurfural formation in the base wine compared to the control. At 15 °C, furfural and homofuraneol had greater concentrations in all chitosan-treated wines after 90 days of storage. Our results demonstrate the potential of mushroom-derived chitosan to remove caftaric acid from grape juice and suggest that chitosan can influence the synthesis of furan-derived compounds in wine after short-term storage.

The dynamics of physicochemical properties, microbial community, and flavor metabolites during the fermentation of semi-dry Hakka rice wine and traditional sweet rice wine.

The dynamics of physicochemical properties, microbial community and flavor metabolites during fermentation of two typical Hakka rice wine were investigated. Results showed that total sugar content was 136.83g/L in sweet rice wine, which almost 8 times higher than that in semi-dry rice wine. Its amino acid contents especially bitterness amino acids were also higher than those in semi-dry rice wine. Most organic acids in Hakka rice wine had the tendency of increase in initial stage of fermentation, following a decrease and finally being almost stable. A total of 131 volatiles including esters, alcohols, aldehydes, acids, ketones were detected. Pediococcus, Bacillus, Acinetobacter, Pantoea, Enterobacter and Lactobacillus were the dominant bacterial genera and Monascus, Saccharomyces, Rhizopus were the dominant fungal genera, which are strongly associated with the significant changes in flavor metabolites during Hakka rice wine fermentation. The obtained findings provided reference data for the optimization of Hakka rice wine fermentation.

Comparative metabolic profiling of Cabernet Sauvignon wines reveals the potential of different Wickerhamomyces anomalus co-fermented with commercial Saccharomyces cerevisiae

In this paper, five Wickerhamomyces anomalus accumulated 9.1–19.7% less released CO2 than S. cerevisiae in the synthetic must. Untargeted metabolomics was used to analyze co-fermented real Cabernet Sauvignon wines. The results showed that all W. anomalus strains significantly decreased the levels of malic acid and hypoxanthine in co-fermented wines, thereby promoting the process of TCA cycle and purine metabolism, respectively. Furthermore, WG5, WG26, and WG27 strains utilized more amino acid, thus favoring the enhancement of aroma compounds. WG27 strain also could biotransform more odorless metabolites into flavor active compounds, such as phenethyl alcohol, indole and indole-3-acetaldehyde. Notably, WG27 strain significantly up-regulated secondary metabolites by more than 400% compared to the other W. anomalus strains. These secondary metabolites were involved in phenylpropanoid and flavonoid metabolism, tryptophan metabolism and methionine metabolism. In addition, co-fermentation with the WG27 strain also resulted in an increase in antioxidant activities by more than 16.09% compared to the control wine. This suggests that the WG27 strain not only improves the flavor and style of the wine but also enhances its antioxidant properties. The findings can be helpful in expanding general understanding of W. anomalus and its potential applications in the food and beverage industry.

Differences in Aroma Profile of Cabernet Sauvignon Grapes and Wines from Four Plots in Jieshi Mountain Region of Eastern China.

The Bohai Bay region is a famous wine-growing area in China, where the rainfall is concentrated in the summer due to the influence of the temperate semi-humid monsoon climate. As such, the vineyard terrain has a significant impact on the flavor quality of the grapes and the resulting wines. To explore the relationship between the 'Cabernet Sauvignon' wine style and terrain, this study takes four different plots in the Jieshi Mountain region to investigate the differences in the aroma profile of Cabernet Sauvignon grapes and wines of two consecutive vintages. Based on two-way ANOVA, there were 25 free and 8 glycosylated aroma compounds in the grapes and 21 and 10 aroma compounds with an odor activity value greater than 0.1 in the wines at the end of alcohol fermentation (AF) and malolactic fermentation (MLF), respectively, that varied among the four plots. Wines from the four plots showed a significant difference in floral and fruity aroma attributes, which were mainly related to esters with high odor activity values. The difference in concentration of these compounds between plots was more pronounced in 2021 than in 2020, and a similar result was shown on the Shannon-Wiener index, which represents wine aroma diversity. It has been suggested that high rainfall makes the plot effect more pronounced. Pearson's correlation analysis indicated that concentrations of (E)-3-hexen-1-ol in grapes and ethyl 3-methylbutanoate, ethyl hexanoate, isoamyl acetate, isopentanoic acid, and phenethyl acetate in wines were strongly positively correlated with the concentrations of N, P, K, Fe, and electrical conductivity in soil but negatively correlated with soil pH. This study laid a theoretical foundation for further improving the level of vineyard management and grape and wine quality in the Jieshi Mountain region.

Electrochemical sensing of caffeic acid antioxidant in wine samples using carbon paste electrode amplified with CdO/SWCNTs

An electrochemical sensor was introduced as an analytical tool for monitoring caffeic acid in food samples. This analytical tool was amplified by cadmium oxide decorated on single wall carbon nanotubes as a new catalyst and showed a powerful ability to sensing of caffeic acid in food products. The presence of cadmium oxide decorated on single wall carbon nanotubes catalyst improved the oxidation signal of caffeic acid about 2.4 times at optimum conditions. The pH investigation confirmed that the redox reaction of caffeic acid was pH dependent and showed maximum sensitivity at pH 7.0. The paste electrode amplified with cadmium oxide decorated on single wall carbon nanotubes was successfully monitored caffeic acid in the concentration range 0.02–200 µM with a detection limit of 9.0 nM, respectively. The standard addition strategy showed a recovery range of 97.96 – 102.59 % to the measurement of caffeic acid in fruit juice, white and red wine that was acceptable for the fabrication of a new analytical tool in food monitoring.

Adsorption Capabilities of Fungoid Chitosan Toward Organic Acids in Model Solutions and White Wine

In oenology, fungoid chitosan (CH) can be used as an adjuvant for microbial control, haziness prevention, metal chelation, and ochratoxin removal. In acidic media (such as wine), CH can ionise and interact with charged compounds, giving rise to a series of adsorption and/or removal phenomena, some of which potentially impairing the overall quality of wines. In this context, it is worth noting that the interaction between CH and acidic components of wines has been poorly studied so far, and detailed information on this subject is still lacking. To study those interactions, different doses of chitosan (0.5; 1.0; 2.0 g/L) were dispersed in hydro-alcoholic solution (HS), synthetic wine solution (SW), and white wine (W). Results demonstrated that the remotion of tartaric acid and the change of pH were strongly affected by the matrix and dosage. In W and SW, chitosan was found to adsorb tartaric acid up to about 200 mg/g and 350 mg/g CH, respectively. Accordingly, pH values increased; however, the magnitude depended on the matrix as a consequence of different buffer capacities. Interestingly, even in the absence of tartaric acid (e.g. in HS samples) CH addition caused a pH increase (up to 1.2 units for 2 g/L CH addition) which demonstrated that pH variations may not only depend on the amount of organic acids adsorbed. The chitosan dispersed in W showed the highest average diameter D [3,2] (127.96 μm) compared to the ones dispersed in SW (120.81 μm) and in HS (116.26 μm), probably due to the presence of organic acids on the polymer surface. The minor removal of tartaric acid in W compared to SW could probably depend on the competitive adsorption onto chitosan of other families of compounds present in wine such as polyphenols. The data suggested that chitosan addition could affect the pH and organic acid concentration of all matrices, depending on the doses and composition of the solutions.

The Ru−Ni bimetallic catalyst activated by high-voltage atmospheric cold plasma (HVACP) and application in the isomerization of grape seed oil

Grape seed oil, as a high-linoleic acid type, can be used for the production of conjugated linoleic acid, which cannot be synthesized by the human body, through isomerization under the action of catalysts. Improving the activity of the catalyst is an effective way to obtain conjugated linoleic acid-rich edible oils. In this study, the Ru−Ni bimetallic catalyst was activated by high-voltage atmospheric cold plasma (HVACP) catalyst modification. The results showed that the specific surface area, pore size distribution, and average particle size of the Ru−Ni bimetallic catalyst were enhanced when the treatment condition was 180 s, the power at both ends of the plate was 150 W, and the gas composition was 5% H2/95% He. The catalyst characterization showed that the dispersion of the HVACP-treated Ru−Ni bimetallic catalyst was enhanced, which elevated the catalytic performance of the catalyst. Linoleic acid in grape seed oil was isomerized by the HVACP-treated Ru−Ni bimetallic catalyst, and grape seed oil rich in conjugated linoleic acid was obtained. The conjugated linoleic acid content, trans oleic acid content, peroxide value, and p-anisidine value were 42.52%, 0.63%, 5.01 mmol kg−1, and 12.41, respectively. Quantum chemical analysis further predicted the reaction sites and clarified the rationality of the isomerization reaction. This method provided a scientific basis for producing high-quality functional oils.

Optimization of a Molecularly Imprinted Polymer Synthesis for a Rapid Detection of Caffeic Acid in Wine.

Molecular imprinting is an efficient strategy to make the detection of compounds more specific and more selective. This targeted analytical strategy using molecularly imprinted polymer (MIP) synthesis needs to obtain the optimized conditions. A selective molecularly imprinted polymer was prepared for caffeic acid (CA) detection after varying the following synthesis parameters: functional monomer type (N-phenylacrylamide, N-PAA or methacrylic acid, MAA), solvent type (acetonitrile/methanol or acetonitrile/toluene), and the polymerization method (UV or thermal initiation). The optimal polymer was obtained using MAA as a functional monomer, acetonitrile/methanol as solvent, and UV polymerization. Morphological characterizations were done for the optimal CA-MIP using mid-infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption. The optimal polymer showed good specificity and selectivity in the presence of interferents (antioxidants having a chemical structure close to CA) in a hydroalcoholic solution. The electrochemical detection of CA was performed by cyclic voltammetry (CV) after the interaction between CA and the optimal MIP in a wine sample. The linear range of the developed method was between 0 and 1.11 mM, the limit of detection (LOD) was 0.13 mM, and the limit of quantification (LOQ) was 0.32 mM. HPLC-UV was used to validate the newly developed method. Recovery values were between 104% and 111%.

Evaluation of Red Wine Acidification Using an E-Nose System with Venturi Tool Sampling.

The quality of wine is checked both during the production process and upon consumption. Therefore, manual wine-tasting work is still valuable. Due to the nature of wine, many volatile components are released, and it is therefore difficult to determine which elements need to be controlled. Acetic acid is one of the substances found in wine and is a crucial substance for wine quality. Gas sensor systems may be a potential alternative for manual wine tasting. In this work, we have developed a TGS2620 gas sensor module to analyze acetic acid levels in red wine. The gas sensor module was refined according to the Venturi effect along with signal slope analysis, providing promising results. The example included in this paper demonstrates that there is a direct relationship between the slope of the MOS gas sensor response and the acetic acid concentration. This relationship is useful to evaluate the ethanol oxidation in acetic acid in red wine during its production process.