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In this work, wine vinegars macerated with figs under different conditions have been characterized for the first time. Samples were analyzed by solid phase microextraction and gas chromatography coupled to mass spectrometry, sensory and physicochemical analysis. The results revealed that fig maceration of wine vinegars influenced the physicochemical, sensory, and volatile profiles of the final product, which were mainly affected by the fig amount (10, 20 or 30%), the fig type (fresh or dry) and the base wine vinegar (young or aged) used, and to a lesser extent the way the fig was added (crushed or chopped). The maceration, regardless the conditions used, increased the fruity notes, overall taste and visual impression, the tonality, total polyphenols and sugar content, and the presence of some volatile compounds, mainly terpenes and ketones, such as (Z)‐p‐mentha‐2,8‐dien‐1‐ol, or β‐damascenone. Therefore, maceration increased the organoleptic complexity, which could enhance the acceptability of consumers towards these products. Practical Application: This research studied how wine vinegars macerated with figs affect in different ways their taste, smell, and chemical properties. Thus, the results showed that these wine vinegars made with fig maceration by using different amounts and types of figs, as well as the type of vinegar used, changed their characteristics, making them smell and taste fruitier and more pleasant. This could be useful for making better‐tasting and more appealing vinegars for consumers who enjoy unique and enhanced flavors in their food. [ABSTRACT FROM AUTHOR]

Wine vinegar, valued for its ancient origins and culinary versatility, has garnered scientific interest due to its complex composition and potential health benefits. This study aims to explore the nutritional and bioactive properties of different wine vinegars, focusing on their amino acid content, particularly tryptophan-derived molecules such as serotonin and melatonin. White wine vinegar, red wine vinegar, port wine vinegar, and balsamic vinegar from the Douro and Rioja regions were analyzed using high-performance liquid chromatography and solid-phase extraction (HPLC-SPE). The study examined the amino acid profiles and the presence of serotonin and melatonin across the samples. The analysis revealed the presence of significant bioactive amino acids, including arginine (found in sample 059 at 61.21 mmol/L), alanine (in a concentration of 30.33 mmol/L in sample 209), and threonine (sample 336 presented the highest concentration—71.47 mmol/L), which have been linked to cardiovascular health, immune system support, and mucosal regulation. The amino acid content varied among the vinegar types, with slower acetification and prolonged aging reducing their concentrations. Tryptophan was mainly found in sample 059 (30.54 mmol/L). These findings, with their potential to influence the scientific community's understanding of the health-promoting properties of wine vinegar, particularly its amino acid content and the potential influence of production processes on bioactive molecules, are of great interest. [ABSTRACT FROM AUTHOR]

Wine vinegar, valued for its ancient origins and culinary versatility, has garnered scientific interest due to its complex composition and potential health benefits. This study aims to explore the nutritional and bioactive properties of different wine vinegars, focusing on their amino acid content, particularly tryptophan-derived molecules such as serotonin and melatonin. White wine vinegar, red wine vinegar, port wine vinegar, and balsamic vinegar from the Douro and Rioja regions were analyzed using high-performance liquid chromatography and solid-phase extraction (HPLC-SPE). The study examined the amino acid profiles and the presence of serotonin and melatonin across the samples. The analysis revealed the presence of significant bioactive amino acids, including arginine (found in sample 059 at 61.21 mmol/L), alanine (in a concentration of 30.33 mmol/L in sample 209), and threonine (sample 336 presented the highest concentration—71.47 mmol/L), which have been linked to cardiovascular health, immune system support, and mucosal regulation. The amino acid content varied among the vinegar types, with slower acetification and prolonged aging reducing their concentrations. Tryptophan was mainly found in sample 059 (30.54 mmol/L). These findings, with their potential to influence the scientific community’s understanding of the health-promoting properties of wine vinegar, particularly its amino acid content and the potential influence of production processes on bioactive molecules, are of great interest.

The aim of this study was to produce non-fermented preserved sea fennel leaves in different pickle juices prepared with apple cider vinegar, wine vinegar and alcoholic vinegar, and to compare their chemical parameters (pH, titratable acidity and salt content), organoleptic properties (color and texture parameters; volatile aromatic compound profiles) and sensory attributes. The pH of the samples ranged from 3.49 to 3.64, the lowest being in the alcoholic vinegar sample and the highest being in the wine vinegar sample, while the titratable acidity and salinity were higher in the alcoholic vinegar pickle juice than those in the other two samples. The volatile aromatic compounds of the samples were also detected. The reddish color of the wine vinegar negatively affected the sea fennel color parameters (L* and b*), and was also negatively evaluated by the panelists, while the alcoholic vinegar maximally preserved the green tones of the leaf (a*). Firmness influences the quality perceived by consumers and was therefore also tested as one of the most important parameters for evaluating the textural and mechanical properties of the different products. All sensory parameters of the sea fennel preserved in alcoholic vinegar, namely color, texture, taste, aroma and overall impression, were given the highest scores, while the sample preserved in wine vinegar received the lowest scores. The intense aroma of the wine vinegar was described as a negative characteristic (off-flavor) of the sample. [ABSTRACT FROM AUTHOR]

Amino acids and biogenic amines are important components of food and beverages. In grape-derived products such as wine and wine vinegar, they can have different origins and can influence the odor and taste of the products. Their concentration is influenced by the grape variety, vintage, and winemaking process. In our study, we carried out an LC-MS-based comparative analysis of 22 grape-derived beverages, including three different wine types and four wine vinegar samples from the Tokaj region in Hungary. The concentrations of 23 amino acids and 10 biogenic amines were examined, and the differences among the sample types were analyzed. The differences in the concentrations of some metabolites between Aszú–Furmint pairs originating from the same wineries and year provide information on the effect of botrytized grape on wine composition. Our data can provide further evidence on how the production process shapes the metabolite content of beverages and highlight the nutritional value of wine vinegar. [ABSTRACT FROM AUTHOR]

The aim of this study was to produce non-fermented preserved sea fennel leaves in different pickle juices prepared with apple cider vinegar, wine vinegar and alcoholic vinegar, and to compare their chemical parameters (pH, titratable acidity and salt content), organoleptic properties (color and texture parameters; volatile aromatic compound profiles) and sensory attributes. The pH of the samples ranged from 3.49 to 3.64, the lowest being in the alcoholic vinegar sample and the highest being in the wine vinegar sample, while the titratable acidity and salinity were higher in the alcoholic vinegar pickle juice than those in the other two samples. The volatile aromatic compounds of the samples were also detected. The reddish color of the wine vinegar negatively affected the sea fennel color parameters (L* and b*), and was also negatively evaluated by the panelists, while the alcoholic vinegar maximally preserved the green tones of the leaf (a*). Firmness influences the quality perceived by consumers and was therefore also tested as one of the most important parameters for evaluating the textural and mechanical properties of the different products. All sensory parameters of the sea fennel preserved in alcoholic vinegar, namely color, texture, taste, aroma and overall impression, were given the highest scores, while the sample preserved in wine vinegar received the lowest scores. The intense aroma of the wine vinegar was described as a negative characteristic (off-flavor) of the sample.

This work aimed to study the properties of acetic fermentation bacteria during the acetic fermentation of wine. Attention was focused on the ability of the bacteria to metabolize selected organic substances and their suitability for wine vinegar production. For the production of wine vinegar, white wine of the variety Veltliner Green was used. Three variants were established for this experiment. The first variant was fermented with Gluconobacter oxydans, the second with Acetobacter aceti, and the third variant of vinegar production was carried out by spontaneous fermentation. During the vinegar fermentation, samples were taken at regular 24-hour intervals and subsequently analyzed. The alcohol, acetic, malic, and tartaric acid contents were monitored. The results showed that all variants showed a strong acetic and malic acid increase. Bacteria Acetobacter aceti produced the most acetic acid within nine days (25 g.L-1). This bacterium also produced the most lactic acid (18 g.L-1). Tartaric acid was also produced in all three variants, but not to the same extent as the previous two organic acids. Acetobacter aceti was found to metabolize ethanol more rapidly than Gluconobacter oxydans.

Amino acids and biogenic amines are important components of food and beverages. In grape-derived products such as wine and wine vinegar, they can have different origins and can influence the odor and taste of the products. Their concentration is influenced by the grape variety, vintage, and winemaking process. In our study, we carried out an LC-MS-based comparative analysis of 22 grape-derived beverages, including three different wine types and four wine vinegar samples from the Tokaj region in Hungary. The concentrations of 23 amino acids and 10 biogenic amines were examined, and the differences among the sample types were analyzed. The differences in the concentrations of some metabolites between Aszú–Furmint pairs originating from the same wineries and year provide information on the effect of botrytized grape on wine composition. Our data can provide further evidence on how the production process shapes the metabolite content of beverages and highlight the nutritional value of wine vinegar.

Vinegar is a fermented product that is appreciated world-wide. It can be obtained from different kinds of matrices. Specifically, it is a solution of acetic acid produced by a two stage fermentation process. The first is an alcoholic fermentation, where the sugars are converted in ethanol and lower metabolites by the yeast action, generally Saccharomyces cerevisiae. This was performed through a technique that is expanding more and more, the so-called "pied de cuve". The second step is an acetic fermentation where acetic acid bacteria (AAB) action causes the conversion of ethanol into acetic acid. Overall, the aim of this research is to follow wine vinegar production step by step through the volatiloma analysis by metal oxide semiconductor MOX sensors developed by Nano Sensor Systems S.r.l. This work is based on wine vinegar monitored from the grape must to the formed vinegar. The monitoring lasted 4 months and the analyses were carried out with a new generation of Electronic Nose (EN) engineered by Nano Sensor Systems S.r.l., called Small Sensor Systems Plus (S3+), equipped with an array of six gas MOX sensors with different sensing layers each. In particular, real-time monitoring made it possible to follow and to differentiate each step of the vinegar production. The principal component analysis (PCA) method was the statistical multivariate analysis utilized to process the dataset obtained from the sensors. A closer look to PCA graphs affirms how the sensors were able to cluster the production steps in a chronologically correct manner. [ABSTRACT FROM AUTHOR]

This work aimed to study the properties of acetic fermentation bacteria during the acetic fermentation of wine. Attention was focused on the ability of the bacteria to metabolize selected organic substances and their suitability for wine vinegar production. For the production of wine vinegar, white wine of the variety Veltliner Green was used. Three variants were established for this experiment. The first variant was fermented with Gluconobacter oxydans, the second with Acetobacter aceti, and the third variant of vinegar production was carried out by spontaneous fermentation. During the vinegar fermentation, samples were taken at regular 24-hour intervals and subsequently analyzed. The alcohol, acetic, malic, and tartaric acid contents were monitored. The results showed that all variants showed a strong acetic and malic acid increase. Bacteria Acetobacter aceti produced the most acetic acid within nine days (25 g.L-1). This bacterium also produced the most lactic acid (18 g.L-1). Tartaric acid was also produced in all three variants, but not to the same extent as the previous two organic acids. Acetobacter aceti was found to metabolize ethanol more rapidly than Gluconobacter oxydans. [ABSTRACT FROM AUTHOR]

Ultraviolet-visible (UV-vis) spectroscopy has shown successful results in the last few years to characterize and classify wine vinegar according to its quality, particularly those with a protected designation of origin (PDO). Due to these promising results, together with the simplicity, price, speed, portability of this technique and its ability to create robust hierarchical classification models, the objective of this work was the development of a computer tool or software, named VinegarScan, which uses the UV-vis spectra to be able to perform quality control and authentication of wine vinegar in a quick and user-friendly way. This software was based on the open-source GUI created in C++ using several data mining algorithms (e.g., decision trees, classification algorithms) on UV-vis spectra. This software achieved satisfactory prediction results with the available analytical UV-vis data. The future idea of utility is to combine the VinegarScan tool with a portable UV-vis device that could be used by control bodies of the wine vinegar industry to achieve a clear differentiation from their competitors to avoid fraud.

The characteristic volatile profile of the Spanish Vinagre de Jerez (VJ), Vinagre de Condado de Huelva (VC) and Vinagre de Montilla-Moriles (VMM) protected designation of origin (PDO) wine vinegars has been studied and compared for the first time by headspace stir bar sorptive extraction-gas chromatography–mass spectrometry (HSSE-GC–MS). The possible markers of each category and PDO were assessed. Acetates were the majority group in all vinegars, while ketones, C 13 -norisoprenoids and volatile phenols showed significant differences between the three PDOs. Analysis of variance (ANOVA), heatmap and partial least squares-discriminant analysis (PLS-DA) were performed. According to these results, 1-heptanol, methyl nonanoate, 2-methylbutanoic acid, 2,2,6-trimethyl-cyclohexanone, trans -2-decenal, eucalyptol and α-terpineol, were the most significant compounds for differentiating of VC, diacetyl and acetoin, ethyl 3-ethoxypropanoate, 2- and 3-heptanone, 2-methyl-1-hexadecanol, 1-octen-3-ol, p -Cresol and camphene for VMM; and β-damascenone, 5-hydroxymethylfurfural, 3-heptanol, trans -2-hexen-1-ol and trans -2-hexen-1-yl acetate for VJ. Classification results showed that 100% of PDO samples were correctly classified, reaffirming the utility of the volatile profiles for classifying and authenticating wine vinegar PDOs. Unlabelled Image • HSSE-GC–MS was used to study the volatile profile of three wine vinegar PDOs. • MCR algorithm was applied for improving the extraction of the volatile compounds. • Some specific compounds were identified as the markers of each PDO. • A perfect classification between PDOs was obtained by PLS-DA models. [ABSTRACT FROM AUTHOR]

In recent years, three Spanish wine vinegars have obtained the indication of Protected Denomination of Origin (PDOs) due to their unique characteristics and traditional method of production: "Vinagre de Jerez", "Vinagre de Condado de Huelva" and "Vinagre de Montilla-Moriles". These vinegars are expensive due to their high quality, the long aging time and the high cost of production, reason why the adulteration and unfair competition in the vinegar industry are frequent practices. To avoid these frauds, several analytical techniques have been already studied for the characterization and authentication of these high quality vinegars. Nevertheless, ultraviolet–visible (UV–vis) spectroscopy, especially attractive for its simplicity and low cost, has not been previously used to assess PDO or other qualities as type of production or aging, in wine vinegars. For this reason, the potential of UV–vis spectroscopy was investigated for the first time as a rapid and inexpensive methodology for developing classification models to discriminate wine vinegars according to the production method, the PDO and the aging category. Spectra from 70 wine vinegars -including different categories within the 3 PDOs and also vinegars without PDO as known as rapid vinegars-have been analyzed and compared in the selected region of 280–600 nm. Principal components analysis (PCA) was used as exploratory method, while soft independent modelling-class (SIMCA) and partial least squares-discriminant analysis (PLS-DA) were employed for the development of a hierarchical classification model. Differences between categories and PDOs, as well as between PDO and Non-PDO wine vinegars, were observed according to the spectral regions around 300 nm and the visible regions around 500 nm. Furthermore, bootstrap resampling method was employed to generate distributions of classification results and to obtain confidence intervals in the classification. The hierarchical classification results open up the possibility of developing a tool that provides an easy and fast differentiation for the authentication of wine vinegars from different categories and denomination of origins. • UV–vis was studied for classifying wine vinegars of different qualities. • A hierarchical classification model was developed by SIMCA and PLS-DA models. • Bootstrap resampling method was used to evaluate the reliability of the results. • Results allowed to classify PDO and Non-PDO wine vinegars, and with different aging. • This method could be an alternative tool for wine vinegar authentication. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: There is growing interest in the beneficial health effects of certain fruits, such as pomegranate, and their by‐products, like vinegar. Vinegars contain antioxidant compounds such as polyphenols, which can scavenge free radicals in the body. In this study, the antioxidant properties (2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid and 2,2‐diphenyl‐1‐picrylhydrazyl scavenging capacities) and global polyphenolic composition of a new functional product, namely a pomegranate vinegar produced in the laboratory from the Gabsi variety, were evaluated and compared with those of commercial wine vinegars (Sherry and Rioja red wine Spanish vinegars). The evolution of the polyphenolic and volatile compositions during production of the pomegranate vinegar was also studied. RESULTS: The results indicate that pomegranate contained a relatively stable total phenolic content that is suitable for the elaboration of vinegar and that this product had an antioxidant capacity comparable to, or even better than, that observed for aged wine vinegars. Regarding the volatiles profile, a high proportion of esters (close to 50%), in relation to alcohols and fatty acids, was observed for pomegranate vinegar, and this is consistent with the high red fruits character identified by sensory analysis. CONCLUSION: Pomegranate vinegar produced in the laboratory has an antioxidant activity and a global phenolic content similar to those of red wine vinegars and higher than most of the white wine vinegars studied. The pomegranate vinegar retained the red fruit sensory character of pomegranate fruit. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

High-quality wine vinegars protected by the indication “Protected Designation of Origin” (PDO) need efficient tools to protect their brands and prevent adulteration and unfair competition. In this sense, Near-Infrared spectroscopy (NIRs) combined with chemometrics has demonstrated its usefulness in food authentication. This work assessed NIRs and Chemometrics as a rapid and non-destructive methodology for this purpose. In this study, 83 high-quality wine vinegars of the Spanish PDOs “ Vinagre de Jerez ”, “ Vinagre de Condado de Huelva ” and “ Vinagre de Montilla-Moriles ” of different categories, and 11 wine vinegars without PDO, were analyzed in the range 12000-4000 cm −1 . Principal component analysis (PCA) was performed to explore the spectra and Partial Least Squares-Discriminant Analysis (PLS-DA) was used to build classification models. The high ability of prediction obtained (>90% correct classification) demonstrated the usefulness of this methodology for authentication of PDO wine vinegars and their categories. [ABSTRACT FROM AUTHOR]

Wine vinegar is an increasingly appreciated product in Europe and some high-quality vinegars have been certified with “Protected Designation of Origin” (PDO) to preserve and control their production methods. Spain has three of the five PDO wine vinegars existing in Europe. A tentative study was carried out to assess the utility of stable isotope analysis (δ13C and δ18O) for the characterization of those Spanish wine vinegars and if the values obtained could be used as a fingerprint of their geographical origin compared with other regions. A total of 35 wine vinegar samples, belonging to the three Southern Spain PDOs and three Northern Spain non-PDO regions, were analyzed for their isotopic composition. Our analysis revealed that most of the Spanish vinegars presented δ13C values that were in agreement with some other isotopic studies about Mediterranean vinegars, since all the samples were under − 20‰ and the vast majority of them were below − 24‰. On the other hand, the δ18O analysis confirmed its utility for discriminating all the Spanish vinegars according to the three geographical coordinates (latitude, longitude and altitude). Positive mean values were associated to Southern vinegars (2.16 ± 1.59‰) and negative δ18O values were related with Northern vinegars (− 2.93 ± 2.82‰). We also found a highly significant (p < 0.001) correlation of δ18O with altitude (R2 = − 0.48) and longitude (R2 = 0.36), which allowed us to conclude that δ18O analysis could be used as a fingerprint of the geographical origin in Spanish wine vinegars. [ABSTRACT FROM AUTHOR]

This study assessed the potential of near infrared (NIR) spectroscopy as a non-destructive method for characterizing Protected Designation of Origin (PDO) “Vinagres de Montilla-Moriles” wine vinegars and for classifying them as a function of the manufacturing process used. Three spectrophotometers were evaluated for this purpose: two monochromator instruments (Foss NIRSystems 6500 SY-I and Foss NIRSystems 6500 SY-II; spectral range 400–2,500 nm in both cases) and a diode-array instrument (Corona 45 VIS/NIR; spectral range 380–1,700 nm). A total of 70 samples were used to predict major chemical quality parameters (total acidity, fixed acidity, volatile acidity, pH, dry extract, ash, acetoin, methanol, total polyphenols, color (tonality and intensity), and alcohol content), and to construct models for the classification of vinegars as a function of the manufacturing method used. The results obtained indicate that this non-invasive technology can be used successfully by the vinegar industry and by PDO regulators for the routine analysis of vinegars in order to authenticate them and to detect potential fraud. Slightly better results were achieved with the two monochromator instruments. The findings also highlight the potential of these NIR instruments for predicting the manufacturing process used, this being of particular value for the industrial authentication of traditional wine vinegars.

Wine vinegars from three Protected Designations of Origin (PDO), Vinagre de Jerez (J), Vinagre de Montilla-Moriles (MM) and Vinagre del Condado de Huelva (CH) from Andalusia, Southern Spain, were investigated for their mineral elements content. Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Sr, V and Zn were determined by inductively coupled plasma optical-emission (ICP-OES). Jerez vinegars had a statistically significant higher Sr content than the others, while with respect to B the same was true for Montilla-Moriles vinegars. Moreover, the ageing time of the vinegars clearly played a role in vinegar mineral content, with higher mineral levels found in aged vinegars than in young ones, especially in samples from Condado de Huelva. Multivariate analysis was performed in order to assess if the vinegars' geographical classification was possible through their elemental profile. Classification models were obtained by LDA and SVM, achieving good prediction abilities, 73 and 80%, respectively. [ABSTRACT FROM AUTHOR]

There is increasing interest in producing novel high quality vinegars. In this work, we examined the effect of biological ageing of white wine on its nitrogen composition (viz. amino acids, urea and ammonium ion, which constitute the main sources of nitrogen for acetic bacteria during the acetification process) with a view to confirming the suitability of aged wine for producing quality vinegar. Available nitrogen contents in biologically aged wine were lower than in young (unaged) wine; this resulted in a slightly lower acetification rate and production with the former. The nitrogen composition of the two vinegars was very similar, with L-proline and L-cysteine as the major amino acids. By exception, only the vinegar from the young wine contained ammonium ion. The ageing process by flor yeast produces urea which is eliminated by the bacteria in the next stage. Available nitrogen for use by acetic bacteria in biologically aged wine is seemingly no limiting factor for acetification. The problem posed by the formation of urea during wine ageing was suppressed by the subsequent acetification process. The study could be an example of how different microorganisms use the available substrate in serial biotransformations. [ABSTRACT FROM AUTHOR]

This study assessed the potential of near infrared (NIR) spectroscopy as a non-destructive method for characterizing Protected Designation of Origin (PDO) "Vinagres de Montilla-Moriles" wine vinegars and for classifying them as a function of the manufacturing process used. Three spectrophotometers were evaluated for this purpose: two monochromator instruments (Foss NIRSystems 6500 SY-I and Foss NIRSystems 6500 SY-II; spectral range 400-2,500 nm in both cases) and a diode-array instrument (Corona 45 VIS/NIR; spectral range 380-1,700 nm). A total of 70 samples were used to predict major chemical quality parameters (total acidity, fixed acidity, volatile acidity, pH, dry extract, ash, acetoin, methanol, total polyphenols, color (tonality and intensity), and alcohol content), and to construct models for the classification of vinegars as a function of the manufacturing method used. The results obtained indicate that this non-invasive technology can be used successfully by the vinegar industry and by PDO regulators for the routine analysis of vinegars in order to authenticate them and to detect potential fraud. Slightly better results were achieved with the two monochromator instruments. The findings also highlight the potential of these NIR instruments for predicting the manufacturing process used, this being of particular value for the industrial authentication of traditional wine vinegars. [ABSTRACT FROM AUTHOR]

Abstract: Production of wine vinegar by fermenting dried grapes and rehydrating with tap water is not allowed by European Regulations. In this study we proved experimentally that δ18O analysis of beverage water, officially used to detect the watering of wine and rehydration of concentrated fruit juice, can also be applied to vinegar to detect this kind of fraud. We considered fourteen production chains from wine to the corresponding raw vinegar and diluted vinegar (6% of acidity), and the official European wine databank established according to . δ18O limit values of −2‰ and −5‰ were defined for raw and diluted vinegars produced from fresh grapes. Values lower than these limits indicate a significant addition of water to a starting matrix with a sugar concentration much higher than fresh grapes. On this basis, more than 60% of 92 suspicious wine vinegars imported to the Italian market were shown not to be authentic, but rather obtained by diluting a concentrated source such as dried grapes with water. [Copyright &y& Elsevier]

Abstract: Changes in the volatile components of red wine vinegars and balsamic vinegars were investigated during 1year of aging in wood barrels and bottles. Barrels of four different woods (oak, chestnut, acacia and cherry) were used. A total of 57 volatile compounds were analysed by Gas Chromatography–Flame Ionization Detection (GC–FID) and Headspace Sorptive Extraction GC–Mass Spectrometry (HSSE-TD–GC–MS). We observed significant increases in the total content of volatile compounds only for balsamic vinegars. The concentrations of ethyl furoate, ethyl benzoate, benzaldehyde and acetophenone were highest in cherry barrels. These compounds, then, seem to be characteristic of this wood. Oak lactones presented the highest increases for vinegars aged in oak. Eugenol was only present in vinegars aged in chestnut and oak barrels. Oak and cherry seem to be the best type of wood for aging of vinegar due to their distinctive aromatic characteristics. [Copyright &y& Elsevier]

Technical improvement of vinegar production encompasses essential modifications to obtain quality products in a relatively short period of time. There are mainly two types of acetic fermentation processes to elaborate vinegar: surface and submerged culture system. High quality products are elaborated by the surface culture system. Quality, as a degree of excellence, is a subjective concept where human sensory organs play an important role to determine the acceptability of a product by the consumer. The quality of vinegars can be evaluated by using a trained sensory panel, but more rapid and objective characterization is achieved by instrumental measurements. Physicochemical analyses are generally aimed at meeting of legislative requirements for the quality, safety and characterization of foods or condiments like vinegar. Sensory analysis is a good tool to determine the category and degree of acceptance of given vinegars. Unfortunately, sensory analysis of vinegar is very difficult to perform since the pungent sensation restricts the number of samples that can be analysed at a time. Therefore, the appropriate sensory analysis method must be clearly defined and the attributes used in discriminant analysis or descriptive tests should be precise and well recognized by the panel. [ABSTRACT FROM AUTHOR]

Samples of commercial wine vinegar were introduced in an axially viewed inductively coupled plasma optical emission spectrometry instrument (AX-ICP OES) equipped with different sample introduction systems: a cross-flow nebulizer combined with a double-path spray chamber (CF-DP) and cone spray associated with a cyclone spray chamber (CS-CC). Samples of white and red wine vinegar were diluted with water before analysis. Higher magnesium Mg II/Mg I ratios (11 and 10 for CS-CC and CF-DP, respectively) were obtained using a nebulization gas flow rate of 0.6 l min-1 and an applied power of 1.3 kW. The background equivalent concentrations (BEC) and signal-to-background ratio (SBR) of analytes were improved using scandium (Sc) as the internal standard. The limits of detection (LOD) and limits of quantification (LOQ) for mineral constituents were similar for both introduction systems. Best recoveries values were obtained using a plasma under robust conditions, CS-CC system and Sc as the internal standard. The concentration determined in 13 commercial samples of wine vinegars varied between 0.2 and 3.0, between 0.02 and 0.4, between 8.5 and 100.0, between 0.01 and 0.05, between 27.0 and 540.0, between 4.0 and 79.0, between 0.4 and 10.0, and between 0.01 and 2.0 for aluminium (Al), barium (Ba), calcium (Ca), copper (Cu), potassium (K), magnesium (Mg), manganese (Mn), and zinc (Zn), respectively. [ABSTRACT FROM AUTHOR]

Abstract: A method for quality control of wine vinegar has been developed based on near-infrared spectroscopy that can be applied to monitor processes or in quality control in vinegar industries. In vinegar production, stages such as on-line fermentation monitoring, dilution process and quality control of the final product are relevant and necessary. The aim of this study was to achieve and simplify these manufacturing stages through the determination of 14 parameters from a spectral measurement. Total acids, non-volatile and volatile acids, organic acids, l-proline, solids, ash and chloride in vinegar were determined by near-infrared spectroscopy. Different data pre-processing methods such as orthogonal signal correction, multiplicative scatter correction or column centering were used and the final multivariate methods were evaluated and compared. The calibration models were validated and prediction capacity studied in order to examine their practical applicability to the vinegar industry. [Copyright &y& Elsevier]

Abstract: Antioxidant activity of commercial red (n =5) and white (n =5) grape juices and wine vinegars (n =5) were determined by the oxygen radical absorbance capacity (ORAC) assay using fluorescein (FL) as fluorescent probe. The ORAC-FL values varied from 14.6 to 25.0 μmol of trolox equivalents/ml for red grape juices, from 3.5 to 11.1 μmol of trolox equivalents/ml for white grape juices, and from 4.5 to 11.5 μmol of trolox equivalents/ml for wine vinegars. Differences in the antioxidant activities among grape juice, wine, and vinegar were attributed to their different phenolic contents and compositions and to other non-phenolic antioxidants present in the samples. These data confirm grape juice and wine vinegar as good dietary sources of antioxidants. [Copyright &y& Elsevier]

The most common fraudulent practice in the vinegar industry is the addition of alcohol of different origins to the base wine used to produce wine vinegar with the objective of reducing manufacturing costs. The mixture is then sold commercially as genuine wine vinegar, thus constituting a fraud to consumers and an unfair practice with respect to the rest of the vinegar sector. A method based on near-infrared spectroscopy has been developed to discriminate between white wine vinegar and alcohol or molasses vinegar. Orthogonal signal correction (OSC) was applied to a set of 96 vinegar NIR spectra from both original and artificial blends made in the laboratory, to remove information unrelated to a specific response. The specific response used to correct the spectra was the extent of adulteration of the vinegar samples. Both raw and corrected NIR spectra were used to develop separate classification models using the potential functions method as a class-modeling technique. The previous models were compared to evaluate the suitability of near-infrared spectroscopy as a rapid method for discrimination between vinegar origin. The transformation of vinegar NIR spectra by means of an orthogonal signal-correction method resulted in notable improvement of the specificity of the constructed classification models. The same orthogonal correction approach was also used to perform a calibration model able to detect and quantify the amount of exogenous alcohol added to the commercial product. This regression model can be used to quantify the extent of adulteration of new vinegar samples. [ABSTRACT FROM AUTHOR]

Assays of accelerated aging in wine vinegars were performed with 2% w/v of oak chips and different pretreatments (toasted at 180 °C, or boiled and toasted at 180 °C). An analytical method for determining volatile compounds from wood (volatile phenols, whisky–lactones, vanillin, etc.) in wine vinegars was set up. This method consisted of a solid phase extraction step followed by gas chromatography. When traditional aging for 180 days (oak barrels) and accelerated aging for 15 days were compared, the results showed that the biggest difference was the rate of extraction for vanillin. Oak-chip aging increased the concentration of this compound 20-fold. Levels of oak-lactone isomers were higher when only toasted oak chips were used. Other factors such as ethanol content or the use of barrels have also been considered. We conclude that oak chips (only toasted) are a valuable alternative to oak barrels for obtaining, in a short period of time (15 days), wine vinegars with the peculiar characteristics given by oak wood. [Copyright &y& Elsevier]