Vinegar Samples Research Articles

Highly sensitive detection of kojic acid in food samples using fluorescent carbon dots derived from pomegranate peel

Kojic acid (KA) has gained significant attention due to its widespread use in the food and cosmetics industries. However, concerns about its potential carcinogenic effects have heightened the need for sensitive detection methods. This study introduces a fluorescence-based optical sensor for the quantification of KA in food samples, utilizing fluorescent carbon dots (CDs) synthesized from pomegranate peel via a hydrothermal method. The Stern–Volmer plot demonstrated a linear response for KA in the range of 120 to 1200 µM, with a Pearson correlation coefficient (r) of 0.9999 and. The sensor exhibited a detection limit of 30 ± 0.04 µM and a limit of quantification (LOQ) of 90 ± 0.14 µM. Application of the developed method to soy sauce and vinegar samples yielded accurate KA determinations, with recoveries of 103.11 ± 0.96% and 104.45 ± 2.15%, respectively. These findings highlight the potential of the proposed sensor for practical applications in food quality and safety assessment, offering valuable insights into the presence of KA in food products.

Multivariate Optimization of an Analytical Method for Bisulfite Determination in Vinegar Samples Using Digital Images

Multivariate Optimization of an Analytical Method for Bisulfite Determination in Vinegar Samples Using Digital Images

Bioactive, Pro-Apoptotic-Angiotensin Converting Enzyme Inhibitor Effects and Properties of Ultrasound-Treated Traditional Poppy Vinegar Using the Response Surface Methodology Model.

Poppy vinegar with functional properties is a fermented product. This study evaluated traditionally produced poppy vinegar. The study was conducted on poppy vinegar to determine the maximum increase in angiotensin converting enzyme (ACE) inhibitory activity %, total phenolic content (TPC), and radical scavenging activity (DPPH) of the vinegar at different combinations of ultrasound treatment duration (2-14 min) and amplitude (40-100%). The optimal parameters obtained using the response surface methodologies (RSM) were the duration of the ultrasound of 5.5 min and the amplitude of the ultrasound at 57%. When the DPPH values, ACE inhibition %, and TPC and DPPH values obtained with the RSM model were compared with the experimental values, the difference was 9.80, 3.0, and 4.6%, respectively, showing good agreement between actual and predicted values. The higher ultrasound intensities and longer treatment times had a significant effect on antioxidant activity. Poppy vinegar samples significantly induced the apoptosis of lung cancer cells, particularly those stored for 6 and 12 months. The amounts of protocatechuic acid, gallic acid, neohesperidin, hydroxybenzoic acid, resveratrol, rutin, trans-cinnamic acid, quercetin, and flavon in poppy vinegar were determined, which decreased significantly as storage time increased. TPC and TFC were determined to be 90.39 mg of GAE/100 mL and 29.86 mg of TEAC/mL, respectively, and there was no significant change in these bioactive compounds after 6 months of storage. The highest value of ACE inhibitory activity was found at the beginning of the storage period. The present study was the first study to examine the bioactive components, ACE inhibition activity, pro-apoptotic activities, and phenolic composition of traditionally produced ultrasound-treated poppy vinegar during storage. The control of production parameters and the design of ideal poppy vinegar fermentation processes could benefit from this research.

Assessment of 5-Hydroxymethylfurfural in Food Matrix by an Innovative Spectrophotometric Assay.

Foods contaminants pose a challenge for food producers and consumers. Due to its spontaneous formation during heating and storage, hydroxymethylfurfural (HMF) is a prevalent contaminant in foods rich in carbohydrates and proteins. Colorimetric assays, such as the Seliwanoff test, offer a rapid and cost-effective method for HMF quantification but require careful optimization to ensure accuracy. We addressed potential interference in the Seliwanoff assay by systematically evaluating parameters like incubation time, temperature, and resorcinol or hydrochloric acid concentration, as well as the presence of interfering carbohydrates. Samples were analyzed using a UV-Vis spectrophotometer in scan mode, and data obtained were validated using HPLC, which also enabled quantification of unreacted HMF for assessing the protocol's accuracy. Incubation time and hydrochloric acid percentage positively influenced the colorimetric assay, while the opposite effect was observed with the increase in resorcinol concentration. Interference from carbohydrates was eliminated by reducing the acid content in the working reagent. HPLC analyses corroborated the spectrophotometer data and confirmed the efficacy of the proposed method. The average HMF content in balsamic vinegar samples was 1.97 ± 0.94 mg/mL. Spectrophotometric approaches demonstrated to efficiently determine HMF in complex food matrices. The HMF levels detected in balsamic vinegars significantly exceeded the maximum limits established for honey. This finding underscores the urgent need for regulations that restrict contaminant levels in various food products.

Portable fiber-optic sensor for simple, fast, cost-effective, and environmentally friendly quantification of total acidity in real-world applications

In this work, an innovative fiber-optic sensor for measuring total acidity (TA: expressed as the % w/v of acetic acid) in beverages was developed. For this purpose, we relied on the kinetic principles of heterogeneous solid-phase reactions (slow reactions due to diffusion processes) to develop a novel pH-sensitive fluorescent membrane calibration method for the quantification of TA. In the proposed calibration method, a linear relationship between TA and the protonation rate of a pH-sensitive fluorescent membrane with a pKa ≥ 9 (Paper-FM) is established. Paper-FM was synthesized by the covalent immobilization of the pH-probe Nile Blue on a porous paper membrane. In addition, a 3D-printed interface was designed to implement Paper-FM into a 0.5 mm diameter optical fiber. The fiber-optic sensor developed in this work was tested by analyzing 21 vinegar samples of different origins, and the results were successfully validated with a reference titration method. The results presented in this work show that our fiber-optic sensor allows a direct, simple, and fast (15 s response time) quantification of TA in vinegar samples. In addition, it is environmentally friendly, because, unlike titration methods, it does not generate toxic waste, is reversible, and is extremely stable (a 0.9 mm diameter circle of Paper-FM allows at least 50 consecutive measurements).

Orange passion fruit (Passiflora caerulea L.) as a new raw material for acetic fermentation: evaluation of organic acids and phenolic profile, in vitro digestion, and biological activities.

This study evaluated for the first time the potential of orange passion fruit as a base for alcoholic and acetic fermentations, with a view to assessing its profile of organic acids and polyphenols, in vitro digestion, and biological activities. In terms of aliphatic organic acids, malic acid was the majority in the wine (3.19 g L-1), while in the vinegar, it was acetic acid (46.84 g L-1). 3,4-Dihydroxybenzoic acid (3,4-DHB) was the major phenolic compound in the wine and vinegar samples (3443.93 and 2980.00 μg L-1, respectively). After the in vitro gastrointestinal simulation stage, the wine showed high bioaccessibility for the compounds sinipaldehyde (82.97%) and 2,4-dihydroxybenzoic acid (2,4-DHBA, 81.27%), while the vinegar exhibited high bioaccessibility for sinipaldehyde (89.39%). Through multivariate analysis, it was observed that 3,4-DHB was highly concentrated in the different digested fractions obtained from the wine. In contrast, in the vinegar, the stability of isorahmenetin and Quercetin 3-o-rhamnoside was observed during the in vitro digestion simulation. Lastly, the vinegar stood out for its inhibition rates of α-amylase (23.93%), α-glucoside (18.34%), and angiotensin-converting enzyme (10.92%). In addition, the vinegar had an inhibitory effect on the pathogenic microorganisms Salmonella enteritidis, Escherichia coli, and Listeria monocytogenes. Orange passion fruit has proved to be a promising raw material for the development of fermented beverages. Therefore, this study provides an unprecedented perspective on the use and valorization of orange passion fruit, contributing significantly to the advancement of knowledge about fermented products and the associated nutritional and functional possibilities. © 2024 Society of Chemical Industry.

Exploring the Impact of Various Wooden Barrels on the Aromatic Profile of Aceto Balsamico Tradizionale di Modena by Means of Principal Component Analysis.

The study examines the unique production process of Aceto Balsamico Tradizionale di Modena PDO (ABTM), emphasizing its complex phases and the impact of raw materials and artisanal skill on its flavor characteristics. Analytical tests focused on the volatile composition of vinegars from different wood barrels at different aging stages, using solid-phase micro-extraction (SPME) coupled with gas chromatography, either with mass spectrometry (GC/MS) or flame ionization detector (FID). Multivariate analysis, including principal component analysis (PCA), was employed to investigate the presence of peculiarities among the volatile profiles of samples of different barrel origin. The research focuses on characterizing the volatile composition of vinegars sourced from individual wood barrels, such as Cherry, Chestnut, Mulberry, Juniper, and Oak. Although it was not possible to identify molecules directly connected to the woody essence, some similarities emerged between vinegar samples from mulberry and cherry barrels and between those of juniper and oak. The former group is characterized by analytes with high molecular weights, such as furfural and esters, while the latter group shows more intense peaks for ethyl benzoate. Moreover, ethyl benzoate appears to predominantly influence samples from chestnut barrels. Due to the highly complex production process of ABTM, where each battery is influenced by several factors, this study's findings are specific to the current experimental conditions.

Date Vinegar: First Isolation of Acetobacter and Formulation of a Starter Culture.

There is a lack of scientific analysis and control over the production of date vinegar in Oman, despite its growing demand in the worldwide market. Traditional production of date vinegar may lead to elevated amounts of ethanol (≥0.5%) and reduced content of acetic acid (<4%) compared to the standard acceptable levels. This study aimed to isolate non-Gluconobacter species from date vinegar produced by spontaneous fermentation and formulate starter cultures for quick and efficient production of date vinegar. In spontaneous fermentation date vinegar samples, the highest concentration of acetic acid was 10.42% on day 50. Acetobacter malorum (5 isolates), A. persici (3 isolates), and A. tropicalis (3 isolates) were identified based on 16S rRNA gene sequences for the first time in date vinegar. For date vinegar prepared with a starter culture of Acetobacter and yeast, the highest concentration of acetic acid was 4.67%. In conclusion, spontaneous fermentation resulted in the production of date vinegar with a high concentration of acetic acid, acceptable concentrations of ethanol and methanol, and the first isolation of three Acetobacter species. The formulated starter culture produced acceptable amounts of acetic acid and the time of fermentation was reduced 10 times (from 40 days to 4 days). This can provide the basis for producing a personalized or commercial product that ensures the production of good-quality date vinegar in an easier, faster, safer, and more efficient way from low-quality and surplus dates.

Optimization of sensory properties of ultrasound-treated strawberry vinegar

Vinegar is renowned for its benefits to human health due to the presence of antioxidants and bioactive components. Firstly, this study optimized the production conditions of ultrasound-treated strawberry vinegar (UT-SV), known for its high consumer appeal. The sensory properties of UT-SV were optimized by response surface methodology (RSM) to create the most appreciated strawberry vinegar. Secondly, various quality parameters of conventional strawberry vinegar (C-SV), UT-SV, and thermally pasteurized strawberry vinegar (P-SV) samples were compared. RSM was employed to craft the best strawberry vinegar based on consumers ratings of UT-SV. Sensory characteristics, bioactive values, phenolic contents, and organic acid contents of C-SV, UT-SV, and P-SV samples were assessed. Through optimization, the ultrasound parameters of the independent variables were determined as 5.3 min and 65.5 % amplitude. The RSM modeling levels exhibited high agreement with pungent sensation at 98.06 %, aromatic intensity at 98.98 %, gustatory impression at 99.17 %, and general appreciation at 99.26 %, respectively. Bioactive components in UT-SV samples increased after ultrasound treatment compared to C-SV and P-SV samples. Additionally, the amount of malic acid, lactic acid, and oxalic acid increased after ultrasound treatment compared to C-SV samples. Ultimately, UT-SV with high organoleptic properties was achieved. The ultrasound treatment positively impacted the bioactive values, phenolic and organic acid content, leading to the development of a new and healthy product.

Investigation of bioactive compounds and their correlation with the antioxidant capacity in different functional vinegars

There are complex and diverse substances in traditional vinegars, some of which have been identified as biologically active factors, but the variety of functional compounds is currently restricted. In this study, it was aimed to determine the bioactive compounds in 10 typical functional vinegars. The findings shown that total flavonoids (0.21–7.19 mg rutin equivalent/mL), total phenolics (0.36–3.20 mg gallic acid equivalent/mL), and antioxidant activities (DPPH: 3.17–47.63 mmol trolox equivalent/L, ABTS: 6.85–178.29 mmol trolox equivalent/L) varied among different functional vinegars. In addition, the concentrations of the polysaccharides (1.17–44.87 mg glucose equivalent/mL) and total saponins (0.67–12.46 mg oleanic acid equivalent/mL) were determined, which might play key role for the function of tested vinegars. A total of 8 organic acids, 7 polyphenol compounds and 124 volatile compounds were measured and tentatively identified. The protocatechuic acid (4.81–485.72 mg/L), chlorogenic acid (2.69–7.52 mg/L), and epicatechin (1.18–97.42 mg/L) were important polyphenol compounds in the functional vinegars. Redundancy analysis indicated that tartaric acid, oxalic acid and chlorogenic acid were significantly positively correlated with antioxidant capacity. Various physiologically active ingredients including cyclo (Pro-Leu), cyclo (Phe-Pro), cyclo (Phe-Val), cyclo (Pro-Val), 1-monopalmitin and 1-eicosanol were firstly detected in functional vinegars. Principle component analysis revealed that volatiles profile of bergamot Monascus aromatic vinegar and Hengshun honey vinegar exhibited distinctive differences from other eight vinegar samples. Moreover, the partial least squares regression analysis demonstrated that 11 volatile compounds were positively correlated with the antioxidant activity of vinegars, which suggested these compounds might be important functional substances in tested vinegars. This study explored several new functionally active compounds in different functional vinegars, which could widen the knowledge of bioactive factor in vinegars and provide new ideas for further development of functional vinegar beverages.

Metal-assisted core-shell plasmonic nanoparticles for small molecule biothiol analysis and enantioselective recognition.

Cysteine (Cys) enantiomorphs, important small-molecule biothiols, participate in various antioxidative, flavoring, and poison-removing processes in the food industry. Current cysteine enantiomorph analysis methods require effective strategies for distinguishing them due to their similar structures and reactivity. Herein, we present a metal ion-assisted enantiomorph-selective surface-enhanced Raman scattering (SERS) biosensor based on an amphiphilic polymer matrix (APM), which can promote cysteine enantiomorph (L/D-Cys) identification. The highly selective molecular orientation is perhaps caused by the intermolecular hydrogen bonding with chiral isomers (metal centers). The experimental results show that the SERS biosensor has a sensitivity-distincting factor toward L-Cys and D-Cys. The linear range is from 1 mmol L-1 to 1 nmol L-1, along with a low limit of detection of 0.77 pmol L-1. Moreover, the fabricated Cu-APM biosensor exhibits remarkable stability and high repeatability, with an RSD of 3.7%. Real food cysteine enantiomorph detection was performed with L-Cys-containing samples of onion, cauliflower, garlic, and apple, and D-Cys-containing samples of vinegar, black garlic, cheese, and beer. The results show that the Cu-APM biosensor can be utilized as a powerful tool for real-time determination of Cys enantiomorphs in different food samples. Thus, the metal-ion-assisted enantiomorph-selective SERS biosensor has potential as an adaptable tool for enantiomorph detection and food sample analysis.

Insights in Electrochemical Determination of Quercetin in Peach Vinegar by the Hexagonal Platinum Nanocrystal.

Peach vinegar is a popular condiment that is thought to have various health benefits. However, the low levels of quercetin and complex detection environment in peach vinegar make it difficult to detect using traditional methods. Electrochemical detection is a promising solution because it is sensitive, inexpensive, and provides real-time results. Herein, a hexagonal Pt nanocrystal was developed as an electrocatalyst for selective detection of quercetin in peach vinegar, and a comprehensive examination was given of the electrochemical characteristics of quercetin when applied to electrodes modified with platinum. The morphology and crystal properties of Pt nanocrystals were analyzed, and the Pt-modified electrode was found to exhibit strong electrocatalytic effects toward quercetin in peach vinegar with a high sensitivity of 58 μA μM-1. Furthermore, the investigation showcased exceptional specificity, consistency, sustained durability, and replicability of the Pt-modified electrode in identifying quercetin. The detection result of the Pt-modified electrode tested in three different peach vinegar samples demonstrated its practical utility in real-world applications. Overall, the findings of this study may have important implications for the development of more efficient and sensitive electrochemical sensors for the detection of quercetin and other analytes in vinegar.

Digital-movie-based flow colorimetry for pH measurement with universal indicators

A continuous, simple, and versatile pH monitoring method based on digital-movie-based colorimetry is proposed. A constructed flow system was of a two-channel configuration mainly composed of two peristaltic pumps, a digital microscope-based detector, a pH meter with a flow-through combination pH-reference electrode, and a laptop computer. While the total flow rate (FT) was held constant, the flow rate (FB) of a base solution for Britton-Robinson buffer containing a universal indicator (Yamada's indicator or Van Urik's indicator) was changed in proportion to the control signal (Vc) from the computer. An acid solution for the buffer containing the indicator was aspirated to the confluence point at the flow rate of FT – FB and mixed with the base solution. Thus, buffer solutions with arbitrary pH could be easily prepared. The image of the mixed solution was captured with the microscope downstream; the pH of the solution was measured with the pH meter at the most downstream. An in-house program written in Visual Basic .NET was developed to control the system, acquire and analyze the signals (image data and pH), and display the results automatically; the color of the image was expressed as tristimulus values (i.e., R, G, B), hue, and luminance. The relationships between these color-specific values and pH were analyzed after optimizing the Vc scan rate. Van Uik's indicator was superior to Yamada's regarding the applicable pH range (ca. 2.5 – 10). A sigmoid-like calibration curve was established between hue and pH, which was used to determine sample pH. The proposed method was validated by measuring the pH of different drugs and vinegar samples.

Exploring the Bioactive Compounds in Some Apple Vinegar Samples and Their Biological Activities.

Apple vinegar is highly recommended for nutrition due to its health benefits and bioactive components. However, the apple cultivar greatly influences the quality of the vinegar. In this research, our focus was on examining the impact of four different apple cultivars on the physicochemical attributes, chemical composition, as well as biological properties-including antidepressant and anti-inflammatory activities-of vinegar. Interestingly, the physicochemical properties of vinegar and the contents of acetic acid and polyphenols depend on the apple cultivars. HPLC chromatographic analysis showed that citric acid (820.62-193.63 mg/100 g) and gallic acid (285.70-54.40 µg/g) were mostly abundant in the vinegar samples. The in vivo results showed that administration of Golden Delicious apple vinegar (10 mL/kg) to adult Wistar rats reduced carrageenan-induced inflammation by 37.50%. The same vinegar sample exhibited a significant antidepressant effect by reducing the rats' immobility time by 31.07% in the forced swimming test. Due to its high acidity, Golden Delicious vinegar was found to be more effective against bacteria, particularly Bacillus subtilis and Candida albicans, resulting in a MIC value of 31.81 mg/mL. Furthermore, the antioxidant activity of various vinegar samples was found to be powerful, displaying optimal values of IC50 = 65.20 mg/mL, 85.83%, and 26.45 AAE/g in the DPPH, β-carotene decolorization and TAC assays, respectively. In conclusion, the apple cultivars used in this study impact the chemical composition and biological activities of vinegar, which may help demonstrate the importance of raw material selection for the production of vinegar.

Multiparametric analysis and authentication of Argentinian vinegars from spectral sources

Ultraviolet-visible (UV-Vis) and near infrared (NIR) spectroscopies allied to chemometrics were investigated for quality control and authentication of Argentinean wine and balsamic vinegars. First, a multiparametric approach was conducted to acquire predictive models by using partial least squares regression (PLS) to quantify total acidity, volatile acidity, fixed acidity, pH and total polyphenols that are the main quality parameters used to control products. Individual UV-Vis and NIR sensors as well as merged data were assessed. Reliability models with correlation coefficients higher than 0.99 and prediction error lesser than 2.2 were acquired for the UV-Vis data. Furthermore, a classification approach was performed on wine vinegar samples to classify them according to their acetification process. At first, the data provided by each individual sensor (UV-Vis and NIR) were separately analyzed by PLS-discriminant analysis. Then, datasets were jointly analyzed by applying sequential and orthogonalized PLS coupled with linear discriminant analysis (SO-PLS-LDA). The overall accuracy of the fused model reached an optimal performance with a value of 0.92 in the prediction stage. Finally, according to the analysis proposed, this work reveals when it is proper to conduct a data fusion methodology.

Vinegar-Preserved Sea Fennel: Chemistry, Color, Texture, Aroma, and Taste.

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.

Characterization of Fruit Vinegars via Bioactive and Organic Acid Profile Using Chemometrics.

Vinegar has been known as a traditional remedy since ancient times. In addition to being used as a flavoring and aroma enhancer in world cuisines, it has attracted more and more attention due to its bioactive potential and health properties. Although the most common use is apple cider vinegar together with grape vinegar, vinegar produced from red fruits has come to the fore due to their health purposes. Rosehip, pomegranate, fig, guelder-rose, blackberry, raspberry, and blueberry vinegars were evaluated regarding the organic acid content, phenolic compound content, and bioactive potential to assess their health potential and associated contents. Acetic acid, citric acid, succinic acid, and malic acid were determined as prominent organic acids in the vinegar samples. In contrast, gallic acid, vanillic acid, protocatechuic acid, and ferulic acid were dominant regarding phenolic compounds. Raspberry, guelder-rose, and pomegranate vinegars came forth regarding their bioactive content and potential. The discriminative parameters of the vinegar samples were pH, total acidity, dL-isocitric acid, gallic acid, and hydroxybenzoic acid. Fruit vinegars were determined to have a notable bioactive content compared to apple and grape vinegars. The use of these vulnerable bioactive materials in vinegar fermentation could provide an effective way for nutrition and raw material resourcing.

Degradation of glucosinolates and formation of isothiocyanates, nitriles, amines, and N,N’-dialk(en)yl thioureas during domestic boiling of red cabbage

Red cabbage is a popular vegetable in Central Europe and a rich source of glucosinolates (GLSs). Upon hydrolysis, GLSs form health-promoting isothiocyanates (ITCs), but also nitriles and epithionitriles. Recently, ITCs were shown to undergo further hydrolysis, yielding amines. Here, we analyzed the degradation of GLSs and the formation of ITCs, nitriles, epithionitriles, and amines during domestic-like cooking of red cabbage with addition of vinegar or baking soda. Both additives strongly affected the stability of GLSs and the formation of nitriles during boiling. Primary amines were found as a major degradation product of GLSs. In control and vinegar samples, formation of methylsulfinylalkyl amines increased during boiling. Additionally, for the first time, the formation of several N,N’-dialk(en)yl thioureas during boiling of Brassica vegetables was demonstrated, resulting from the reaction of GLS-derived ITCs and amines, and they were subsequently quantified. As references, five N,N’-dialk(en)yl thioureas were synthesized and characterized by NMR and HRMS.

Comparative Analysis of Amino Acid and Biogenic Amine Compositions of Fermented Grape Beverages.

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.

Tracing the geographical origin of grain vinegar using the stable isotope ratio mass spectrometry and chemometrics

Shanxi extra-aged vinegar (SX) and Zhenjiang vinegar (ZJ) are prominent vinegar varieties in China, but they frequently fall victim to counterfeit products due to their exclusive geographical indication labels. In this study, the carbon isotope ratio data (δ13C) obtained via elementary analyzer isotope ratio mass spectrometry (EA-IRMS) were employed to effectively distinguish between the two geographical indications of vinegar (SX and ZJ) and other vinegar samples sourced from different regions. The δ13C values were individually measured for vinegar (δ13Ctotal), the protein content extracted from vinegar (δ13Cprotein), and the sugar content extracted from vinegar (δ13Csugar). The results revealed that vinegars with exceptionally low sugar and protein contents can be precisely differentiated from the two geographical indications by directly comparing the δ13Cprotein and δ13Csugar values. Moreover, a linear discriminant analysis (LDA) discriminant analysis model was established, integrating all three δ13C isotope ratio datasets as multi-indicators. The results demonstrated that the proposed model distinctly discriminates 24 SX and 35 ZJ vinegar samples from the remaining 26 vinegar samples. This data indicated that the combination of EA-IRMS and LDA offers a potent tool for enhancing vinegar traceability and safeguarding geographical indications.