Vinegar Samples Research Articles

Application of ultrasound to the organic cornelian cherry (Cornus masL.) vinegar: Changes in antibacterial, antidiabetic, antihypertensive, and anticancer activities

In this study, to determine their alternative/complementary properties, organic cornelian cherry vinegar samples prepared by traditional (CCV), thermal pasteurization (P-CCV), and ultrasound (UT-CCV) methods were tested for antibacterial, antidiabetic, antihypertensive, and anticancer activities. As a result of response surface methodology optimization, the bioactive compounds were increased. With ultrasound treatment, the total phenolic content increased by 4.6%. The antibacterial activity was detected in all samples, while the lowest MIC values (28.4 μl/ml) in the presence of UT-CCV were found in Pseudomonas aeruginosa, Klebsiella pneumoniae, Bacillus cereus, and Staphylococcus aureus. In addition, apoptosis was induced in HT-29 and MDA-MB-231 cells were treated with the CCV, P-CCV, and UT-CCV samples compared to the control group. It was determined that UT-CCV has antidiabetic and antihypertensive effects. Therefore, our study encourages further clinical research on the alternative/complementary property of cornelian cherry vinegar in the treatment of various health manifestations including infections, cancer, diabetes, and hypertension. Novelty Impact Statement Bioactive components of organic cornelian cherry vinegar increased with ultrasound treatment. Organic cornelian cherry vinegar stimulates apoptosis in cancer cells. Vinegar samples prepared by the UT-CCV method show better antibacterial activity compared to CCV and P-CCV samples.

Selection of Acetic Acid Bacterial Strains and Vinegar Production From Local Maltese Food Sources.

This study investigates the isolation, identification, and fermentation performance of autochthonous acetic acid bacteria (AAB) from local niche habitats on the Island of Gozo (Malta) and their further use for vinegar production, employing local raw materials. The bacteria were isolated from grapevine berries and vinegar produced in the cottage industry. Following phenotype and genotype identification, the AAB were ascribed to the genera Acetobacter, Gluconobacter, and Komagataeibacter. A mixture of selected AAB was tested as an inoculum for vinegar production in bench fermenters, under different conditions and substrates, namely, grapes, honey, figs, onions, prickly pear, and tomatoes. The bench fermenters were operated under semi-continuous fermentation where working volumes were maintained by discharging and subsequent recharging accordingly to maintain the acidity in fermenters by adding 30–50 g/l of acetic acid for optimal Acetobacteraceae performance. Finally, the vinegar products obtained from the different substrates were evaluated for their quality, including organoleptic properties, which showed the superior quality of wood-treated vinegar samples with respect to neat vinegar samples.

PH-controlled charge transfer sensitive 2-aminobenzimidazole modified poly(styrene-co-maleic anhydride) copolymer for selective extraction, pre-concentration and determination of trace Hg2+ and CH3Hg+ in vinegar by combination of ultrasound assisted-cloud point extraction with UV–VIS spectrophotometry

In this study, a separation/pre-concentration procedure, ultrasound assisted-cloud point extraction with modified 2-aminobenzimidazole (2-ABzI), was developed for the extraction of trace Hg2+ and CH3Hg+ and from vinegar samples- modified copolymer coupled with Hg-binding chelator, 2-ABzI. The imidic copolymer was characterized, and used for detection of the enriched Hg species by spectrophotometer at 332 nm. The method is based on their pH-induced charge transfer sensitive complexation with copolymer matrix via 2-AmBzI moiety at pH 6.0 and 4.5, and their extraction into the mixed micellar phase of the mixed non-ionic/ionic surfactants as extractant/sensitivity enhancer. The variables influencing the extraction efficiency were optimized. From pre-concentration of 25-mL sample, with a changing calibration sensitivity and pre-concentration factor of 62.5, a good rectilinear relationship between absorbance and concentrations of Hg species in ranges of 1–15, 15–150 µg L−1 was obtained. The detection limits are 0.30 and 0.31 µg L−1, respectively. Its precision/accuracy were in range of 3.1–7.6 % and 90.5–96 % after spiking (n: 5, for measurements of 5, 25 and 100 µg L−1 in same day and three consecutive days). The matrix effect was also studied (n: 3, 100 µg L−1). The method is simple, cost-effective, fast, accurate, safe, highly stable and selective, which has successfully been applied to the speciation of mercury in vinegar.

PRODUCTION OR ACTIVATED CARBON FROM COCONUT SHELL USING DIFFERENT CHEMICALS AND COMPARATIVE ANALYSIS OF THE ADSORPTION EFFICIENCIES.

Activated carbon is a crude form of graphite and a generic term used to describe a family of carbonaceous adsorbent material, possessing a highly crystalline form and extensively developed internal pore structures, colour, texture and odour. In this research, activated carbon was prepared from coconut shell using physicohemical activation method, which includes the treatment with different activating chemical (H204, HCl, ZnCl2, CaO3 CaCl3, H3P04) and pyrolyzation with heat. The processes used include carbonization of simples, oxidation, washing of samples, chemical activation with different activating chemicals serially for 24hrs, drying of samples in an oven for 1hr at a temperature of 1500C, pounding and sieving of samples to different sizes. The percentage yields of the material before activation was 96% and after activation was 93%, respectively. Digital pH meters and digital turbidity meter were the instruments used in the evaluation of the adsorption efficiencies, using samples of vinegar and fresh smelling fish water. The results show that in the order of the adsorption efficiencies of these activating chemicals, ZnCl2 is the lowest adsorption efficiency (45/12%), while CaCl2 has the highest (83.93%).

Influence of balsamic vinegar on the quality indicators of natural semi-finished pork meat products

Lipid oxidation leads to an unpleasant smell and taste of semi-finished meat, which becomes tougher and less juicy due to the loss of intracellular fluid. The purpose of the study is to determine the effect of fruit and berry components of balsamic vinegar on organoleptic, structural, and mechanical parameters and changes in the pH level of semi-finished meat products. The paper presents the results of the influence of various types of balsamic vinegar on the quality indicators of semi-finished meat products. 5 varieties of balsamic vinegar were used: rowan, blackberry, currant, pomegranate, and grape. At the first stage of the study, the pH value was determined in samples of balsamic vinegar from fruit and berry raw materials. The next stage of the study was to determine the effect of balsamic vinegar on the structural and mechanical parameters, pH and organoleptic characteristics of meat during 7 days of storage of semi-finished pork products, which were injected with 5 types of balsamic vinegar in the amount of 15% to the weight of meat. Meat samples were evaluated by appearance, in-section appearance, taste, colour, consistency, and juiciness. Determination of penetration stress in the samples was carried out by measuring the immersion depth of a standard needle in each marinated meat semi-finished product and the control sample of pork meat. It was confirmed that the use of balsamic vinegar made from rowan, black currant, and pomegranate significantly affects the consistency of meat, making it more tender. When interacting with the components of raw materials, food acids affect the taste and aroma, and partially break down proteins and fats, making meat softer and tastier. It was found that in semi-finished pork meat products under the action of balsamic vinegar as one of the components of the marinade, the pH level decreases, which extends the shelf life and prevents the development of bacteria. Organoleptic characteristics and taste and aroma properties of the semi-finished product were improved and the appearance became more pleasant. The obtained results would allow extending the shelf life, enriching with biologically active substances, and improving the consumer properties of the semi-finished product

The Total Content of Polyphenols and the Antioxidant Properties of several Berry Vinegars

Berry fruits represent a valuable source of natural aroma and antioxidants for vinegars. The aim of this research was the evaluation of the
 total polyphenol content (TPC), total anthocyanin content (TAC), and antioxidant properties (by ABTS and DPPH assay) of several vinegars
 produced by an acetous fermentation process, using substrates that contain berry (raspberries, blueberries, blackberries) juice (40%; 60%) inoculated with acetous bacteria (0.5%; 1%). Experimental results indicated that blueberry vinegar samples obtained using 0.5% acetous bacteria and 60% berry juices led to the highest mean values for TPC, TAC, and levels of antioxidant activity, but all these variants had significantly the lowest values of acetic acid content.

A molecularly-imprinted SERS sensor based on a TiO2@Ag substrate for the selective capture and sensitive detection of tryptamine in foods

Herein, a molecularly imprinted surface-enhanced Raman spectroscopy (SERS) sensor was developed for the selective capture and sensitive detection of tryptamine in foods. The SERS sensor exploited silver nanoparticle-decorated TiO2 (TiO2@Ag) substrates for Raman signal enhancement via synergistic effect of electromagnetic enhancement and photoinduced charge-transfer, whilst surface functionalization with the molecularly imprinted polymer ensured selective tryptamine capture. The SERS spectrum of tryptamine on the sensor closely matched that predicted by density functional simulations. The SERS intensity for tryptamine on the developed TiO2@Ag@MIP sensor increased linearly with the logarithm of the tryptamine concentration over the range of 10−6–10−2 mol L−1, with a LOD of 4.85 × 10−7 mol L−1. Tryptamine was detected in a spiked white vinegar sample, and its recoveries were in the range of 92.00%–111.40%. The SERS sensor could be used for the detection of tryptamine in actual samples.

Enantioselective Determination of Hydroxy Amino Acids in Japanese Traditional Amber Rice Vinegars

A fully-automated two-dimensional (2D) HPLC system for the determination of serine (Ser), threonine (Thr) and allo-threonine (aThr) enantiomers was developed. The system was validated and applied to the determination of the target hydroxy amino acid enantiomers in vinegar samples including the Japanese traditional amber rice vinegar. The Japanese traditional amber rice vinegar is one of the typical natural fermented products containing high levels of D-amino acids, and the clarification of the amounts of hydroxy amino acid enantiomers is expected. For the on-line 2D-HPLC system, a narrowbore ODS column (Singularity RP18, 1.0 x 250 mm) was used in the first dimension, and an originally-designed Pirkle-type chiral stationary phase (Singularity CSP-013S, 1.5 x 250 mm) was utilized in the second dimension. The target hydroxy amino acids were derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) and detected by their fluorescence (ex. 470 nm, em. 530 nm). The concentrations and the %D values were compared among a grain vinegar, a widely-distributed black vinegar and Japanese traditional amber rice vinegars (fermented/aged 1 or 5 years by microorganisms in an earthenware jar). The amounts of hydroxy amino acid enantiomers were low (0.21-0.38 μmol/mL, only L-forms) in the grain vinegar, and relatively high amounts of the L-forms were observed (1.05-1.61 μmol/mL) in the widely-distributed black vinegar. On the other hand, clear peaks of the D-forms (0.16-0.86 μmol/mL for D-Ser, 0.02-0.11 μmol/mL for D-aThr) as well as high amounts of the L-forms (2.27-2.51 μmol/mL for L-Ser, 1.85-2.10 μmol/mL for L-Thr) were observed in the Japanese traditional amber rice vinegars. The amounts of D-Ser and D-aThr clearly increased with increasing the fermentation/aging period. This is the first report showing the profiles of the hydroxy amino acid enantiomers simultaneously, and further investigations using various fermented food/beverage samples are expected.

Open Tubular Capillary Electrochromatography-Mass Spectrometry for Analysis of Underivatized Amino Acid Enantiomers with a Porous Layer-Gold Nanoparticle-Modified Chiral Column.

By developing a novel chiral column, we integrate open tubular capillary electrochromatography into sheathless mass spectrometry (MS) for efficient analysis of underivatized amino acid enantiomers. The chiral column is easily fabricated by modifying the inner surface of a capillary with a three-dimensional porous layer (PL, thickness ∼ 90 nm, pore size ∼ 30 nm) and gold nanoparticles and by introducing a chiral selector, thiol β-cyclodextrin (SH-β-CD), onto the modified surface via Au-S bonds. This approach greatly enhances the specific surface area and thus the ratio of the stationary phase to mobile phase and interaction between the stationary phase and analytes. The proposed PLOT@Au@CD column is coupled to the sheathless CE-ESI-MS system for chiral analysis of amino acid enantiomers. No derivatization of amino acids is required for chiral analysis, and baseline separation of a total of 15 pairs of amino acid enantiomers is achieved within 17 min with high column efficiencies of 5.60 × 104 to 1.82 × 106 N/m, high resolutions of 1.51-10.0, and low limits of detection between 0.02 and 0.09 μg/mL. The separation efficiency and MS intensity are only slightly decreased over 60 runs or after usage for 15 days, showing excellent repeatability and stability of the PLOT@Au@CD column. The proposed method is successfully applied to the determination of amino acid enantiomers in vinegar samples with satisfactory accuracy. Our study provides a new approach for developing a chiral stationary phase in the chromatographic separation technique, which can be easily coupled to sensitive MS detection, thus it would be of value for various applications in the fields of chiral analysis.

Effects of Non-Thermal Treatment on Gilaburu Vinegar (Viburnum opulus L.): Polyphenols, Amino Acid, Antimicrobial, and Anticancer Properties.

Simple SummaryIn this study, traditionally produced vinegar made from gilaburu (C-GV) and thermally pasteurized gilaburu vinegar (P-GV), and (ultrasound-treated gilaburu vinegar (UT-GV) were evaluated. At the same time, ultrasound treatment enriched 11 phenolic compounds (gallic acid, protocatechuic acid, hydroxybenzoic acid, vanillic acid, p-coumaric acid, rutin, ferulic acid, o-coumaric acid, neohesperidin, quercetin, trans-cinnamic). Ultrasound showed different effects on free amino acids and volatile profiles. In general, ultrasound showed more positive results than thermal pasteurization. Six important minerals (Ca, Fe, K, Mg, Mn, and Zn) were detected in gilaburu vinegar, and ultrasound treatment increased the Fe content. Gilaburu vinegar, prepared by different methods, had potential antibacterial and anti-cancer activity.Gilaburu (Viburnum opulus L.) is an important fruit that has been studied in recent years due to its phytochemicals and health benefits. In this study, traditionally produced vinegar made from gilaburu fruit (C-GV) was evaluated. Vinegar with higher levels of bioactive components optimized by response surface methodology (RSM) was also produced using ultrasound (UT-GV). The maximum optimization result for the bioactive components was achieved at 14 min and 61.2 amplitude. The effectiveness of thermal pasteurization (P-GV) on gilaburu vinegar was evaluated. An increase was detected for every organic acid with ultrasound treatment. In the UT-GV and C-GV samples, arabinose was present, which is useful for stimulating the immune system. Gilaburu vinegar samples contained 29–31 volatile compounds. The smallest amount of volatile compounds was found in P-GV (1280.9 µg/kg), and the largest amounts of volatile compounds were found in C-GV (1566.9 µg/kg) and UT-GV (1244.10 µg/kg). In the UT-GV sample, Fe was increased, but Ca, K, Mg, and Mn were decreased. A total of 15 polyphenols were detected in C-GV, P-GV, and UT-GV samples, and gallic acid was the most common. A total of 17 free amino acids were detected in gilaburu vinegar samples. Ultrasound provided enrichment in total phenolic compounds and total free amino acids. All three vinegar samples had good antimicrobial activity against pathogens. The efficacy of C-GV, P-GV, and UT-GV samples against colon and stomach cancer was determined, but there were no significant differences between them. As a result, ultrasound treatment is notable due to its antimicrobial and anticancer activity, especially for the enrichment of phenolic compounds and amino acids in gilaburu vinegar.

High-Quality Bioethanol and Vinegar Production from Saudi Arabia Dates: Characterization and Evaluation of Their Value and Antioxidant Efficiency.

Dates are very rich in various nutritious compounds, especially reducing sugars. Sugars ensure both anaerobic and aerobic fermentation, carried out respectively for the production of bioethanol and vinegar. Currently, the world production of dates is constantly increasing owing to the significant improvement in production conditions following the continuous scientific and technological development of this field. The Kingdom of Saudi Arabia is one of the most important world producers of dates, occupying the second place by producing 17% of the total world production. This is why it has become a national priority to find new ways to exploit and further valorize dates and palm waste in the development of new and sustainable products. The present study was designed to explore the possible study of a variety of date palm by-products in the production of bioethanol and vinegar via Saccharomyces cerevisiae. Different parameters of bioethanol and vinegar production, including pH, time, fermentation temperature, and yeast concentration, were studied and optimized. Chemical, physicochemical, purity behavior, and antioxidant performance were carried out via NMR, FTIR, and antioxidant activity essays (TPC, DPPH, FRAP, and β-carotene bleaching test) with the aim to evaluate the potential of the bioethanol and vinegar samples extracted from date palm by-products. Khalas date vinegar revealed significantly more phenolic content (5.81 mg GAE/mL) (p < 0.05) than the different kinds of vinegar tested (Deglet Nour and Black dates; 2.3 and 1.67 mg GAE/mL, respectively) and the commercial vinegar (1.12 mg GAE/mL). The Khalas date vinegar generally showed a higher carotenoid value and better antioxidant activity than the other vinegars extracted from other date varieties and commercially available vinegar. The results confirmed the high quality of the bioethanol and vinegar products, and the efficiency of the developed production processes.

Three-Dimensional Ordered Macroporous Magnetic Inverse Photonic Crystal Microsphere-Based Molecularly Imprinted Polymer for Selective Capture of Aflatoxin B1.

Development of an efficient detection method to monitor residual mycotoxins in food is very important to ensure food safety, but the complex food matrix seriously affects the detection sensitivity and accuracy. Here, using a three-dimensional ordered macroporous magnetic inverse photonic crystal microsphere (MPCM) as the supporting material, a molecularly imprinted polymer (MIP) that can selectively recognize aflatoxin B1 (AFB1) was synthesized through the dummy template imprinting strategy. The MPCM@MIP prepared by employing 5,7-dimethoxycoumarin as the template and methacrylic acid as the functional monomer displayed selectivity toward AFB1 (imprinting factor of 1.5) and could be used as a solid-phase extraction material. By coupling with high-performance liquid chromatography, an analytical method targeting AFB1 was established and displayed a wide linear range of 5-1000 ng/mL with a low detection limit of 0.4 ng/mL. The method showed a good recovery rate of 73-92% in AFB1-spiked soy sauce and vinegar samples. Moreover, the MPCM@MIP could be separated from the sample solution easily because of its magnetic performance, displaying a promising future not only in the enrichment of AFB1 to improve the detection sensitivity and accuracy but also in the removal of AFB1 from food and environmental samples.

Quantitative analysis of multi-components by single-marker: An effective method for the chemical characterization of wood vinegar

Wood vinegar is a complex mixture of organic compounds. QAMS is a relatively simple and cost-effective method which is used widely in recent years. In this study, quantitative analysis of multi-components by single-marker (QAMS) was applied to quantify the main volatile chemical components in wood vinegar for the first time. Using acetic acid as an internal reference compound, the relative correction factors of a further 19 chemical volatile components were obtained. 20 wood vinegar prepared from different lignocellulosic biomass, and at different pyrolysis temperatures, were analyzed by QAMS and the data compared with those obtained using an internal standard (phenethyl acetate) method. The results showed that the precision and repeatability of the QAMS method were good, and the responses obtained for each compound using GC/MS were linear over the corresponding concentration range (R2 ≥ 0.999). The average spike recoveries of 20 volatile compounds from wood vinegar ranged from 92.65% to 105.93% (RSD ＜ 7%, n = 6). There were no significant differences (P > 0.05) in the results obtained from the analysis of three batches of wood vinegar samples (RSD < 2%) using both methods. The volatile composition of samples obtained from wood vinegar prepared from the pyrolysis of different materials and at different temperatures were significantly different. The successful application of QAMS to the quantitative analysis of the composition of wood vinegar not only may provide a theoretical reference for further developments in the production, pyrolysis conditions, and modes of action for wood vinegar, but also provides ideas for the application of QAMS in other fields.

Bioactive components, antibacterial and antiradical properties of home-made apple and grape vinegar

The present study aimed to investigate major volatile compounds, organic acid, phenolic and mineral contents, and antiradical and antimicrobial properties of home-made apple/grape vinegar. Grape vinegar showed higher total acidity, organic acid content, total phenolic content (TPC), antiradical activity and lower minimum inhibitory concentration (MIC) values compared to apple vinegar. While acetic and tartaric acids were the most abundant organic acids in grape vinegar, acetic and succinic acids were the most abundant organic acids in apple vinegar. The most abundant phenolic compound was gallic acid in both grape and apple vinegar. A total of 18 and 9 volatile compounds were determined in grape vinegar samples and apple vinegar samples, respectively. The most abundant volatile compounds were acetic acid and acetoin in grape vinegar, acetic acid, ethyl acetate and 2,4,5-trimethyl-1,3-dioxolane in apple vinegar. K, Ca and Na were common minerals in both vinegar and more in the grape vinegar compared to apple vinegar. Although MIC value for grape vinegar was at 6.25% with minimum bactericidal concentration (MBC) values ranged from 6.25% to 12.50%, MIC value for apple vinegar was at 12.50% with MBC values ranged from 12.50% to 25.00% for all test bacteria. The antiradical and antibacterial activities of the vinegar samples were correlated with their TPC and organic acid contents.

Stable carbon isotopic characterization of rice vinegar protein as an intrinsic reference for discriminating the authenticity of brewed rice vinegar.

Rice vinegar plays an important role in daily life. However, some unscrupulous manufacturers may deliberately add synthetic acetic acid in vinegar products to reduce fermentation time and save production costs. To protect the rights and health of consumers, vinegar authenticity must be controlled. The rice vinegar protein was used as an intrinsic reference and its stable carbon isotope ratio (δ13Cprotein) was analyzed by elemental analyzer-isotope ratio mass spectrometry. The stable carbon isotope ratio difference between the acetic acid and the rice vinegar protein (Δδ13Cacetic acid-protein) was calculated to evaluate vinegar authenticity. Sixteen rice vinegar samples were analyzed and a stable carbon isotopic pattern of rice vinegar was established by the 95% confidence interval for Δδ13Cacetic acid-protein (0.27‰-2.10‰). An acetic acid adulteration curve of Δδ13Cacetic acid-protein was also assumed according to the data from rice vinegar samples, and its validity was confirmed by rice vinegar deliberately blended with acetic acid at different ratios (25, 50, and 75%). The Δδ13Cacetic acid-protein values of the adulterated vinegars decreased with increasing amounts blended acetic acid, but the δ13Cprotein values did not, showing that rice vinegar protein could be used as an intrinsic reference for identifying the adulterated rice vinegar. The rice vinegar adulterated with acetic acid at higher than approximately 10% could be detected.

Inner product of RGB unit vectors for detecting color transition: application to feedback-based flow ratiometric titration.

The inner product (IP) of RGB unit vectors' approach for detecting color transition has further been applied to a feedback-based flow ratiometric titration, including nonaqueous titration. While the flow ratio of titrand/titrant containing an indicator was varying, the video image of the merged solution was taken with a digital microscope downstream. The indicator's color was converted to an RGB unit vector. The change in IP between vectors was used for determining the equivalence point. The concept was successfully applied to the determinations of drug and vinegar samples with reasonable throughput rate (> 18s/titration) and precision (RSD < 4.4%).

Investigation of the microbiota associated with traditionally produced fruit vinegars with focus on acetic acid bacteria and lactic acid bacteria

The microbiological properties of traditionally produced fruit vinegars, i.e., fig, mulberry, apple and plum vinegars, supplied from different cities in Turkey were investigated. The counts of acetic acid bacteria (AAB), lactic acid bacteria (LAB) and mold - yeast for fruit vinegars were found in the range of 2.54–7.05, 1.91–6.81 and 1.32–7.10 log CFU/mL, respectively. The indigenous AAB and LAB isolates were recovered from the vinegars and characterized based on a combination of phenotypic and genotypic approaches including 16S rRNA gene sequencing. In AAB three different species, Acetobacter pasteurianus, A. ghanensis and A. fabarum, and in LAB five species, Lacticaseibacillus paracasei, Lactiplantibacillus plantarum, Levilactobacillus brevis, Leuconostoc sp. and Weisella confusa were identified in the vinegar samples. It was the first study reporting the identification of A. fabarum and Leuconostoc sp., which were isolated from fig vinegar. The results of the study showed that A. pasteurianus and L. paracasei were predominant species found in vinegar samples. The study provides potential strains which may be used as starter cultures in food industry.

The Nutritional and Antioxidant Potential of Artisanal and Industrial Apple Vinegars and Their Ability to Inhibit Key Enzymes Related to Type 2 Diabetes In Vitro.

The main objective of the current study was to determine the physicochemical properties, antioxidant activities, and α-glucosidase and α-amylase inhibition of apple vinegar produced by artisanal and industrial methods. Apple vinegar samples were analyzed to identify their electrical conductivity, pH, titratable acidity, total dry matter, Brix, density, mineral elements, polyphenols, flavonoids, and vitamin C. The antioxidant activity of apple vinegar samples was evaluated using two tests, total antioxidant capacity (TAC) and DPPH radical scavenging activity. Finally, we determined α-glucosidase and α-amylase inhibitory activities of artisanal and industrial apple vinegar. The results showed the following values: pH (3.69–3.19); electrical conductivity (2.81–2.79 mS/cm); titratable acidity (3.6–5.4); ash (4.61–2.90); °Brix (6.37–5.2); density (1.02476–1.02012), respectively, for artisanal apple vinegar and industrial apple vinegar. Concerning mineral elements, potassium was the most predominant element followed by sodium, magnesium, and calcium. Concerning bioactive compounds (polyphenols, flavonoids, and vitamin C), the apple vinegar produced by the artisanal method was the richest sample in terms of bioactive compounds and had the highest α-glucosidase and α-amylase inhibition. The findings of this study showed that the quality and biological activities of artisanal apple vinegar were more important than industrial apple vinegar.

Detection and Identification of Adulteration in Vinegar Samples Based on Reversed-Phase High-Performance Liquid Chromatographic (RP-HPLC) Strategies

Adulteration of vinegar to gain economic benefit has become a common practice in recent years. RP-HPLC strategies were proposed for the assurance of the concentration of acetic acid, rare organic acids (tartaric, malic, lactic and citric), and acetaldehyde in Egyptian vinegar samples. The flow rate was 0.5 mL/min using UV detection at 210 and 365 nm for organic acid and acetaldehyde, respectively. The linearity was 0.05–0.60 g/100 mL for acetic acid, 0.01–0.12 g/100 mL for citric, malic, and tartaric acids, 0.005–0.060 g/100 mL for lactic acid, and 0.02–0.16 mg/L for acetaldehyde with r2 > 0.999. Shortest retention time was at 2.38 min for acetic acid. %RSD for repeatability and reproducibility were <2%. The methods are accurate and precise with recoveries ranging from 94.20 ± 2.28 to 116.41% ± 3.70. The acquired information recommended that these techniques could successfully investigate diverse organic acids in real samples, and they have a wide extent of utilization.

Physicochemical parameters combined flash GC e-nose and artificial neural network for quality and volatile characterization of vinegar with different brewing techniques

Vinegar is a kind of traditional fermented food, there are significant variances in quality and flavor due to differences in raw ingredients and processes. The quality assessment and flavor characteristics of 69 vinegar samples with 5 brewing processes were analyzed by physicochemical parameters combined with flash gas chromatography (GC) e-nose. The evaluation system of quality and the detection method of flavor profile were established. 17 volatile flavor compounds and potential flavor differential compounds of each brewing process were identified. The artificial neural network (ANN) analysis model was established based on the physicochemical parameters and the analysis of flash GC e-nose. Although the physicochemical parameters were more intuitive in quality evaluating, the flash GC e-nose could better reflect the flavor characteristics of vinegar samples and had better fitting, prediction and discrimination ability, the correct rates of training and prediction of flash GC e-nose trained ANN model were 98.6% and 96.7%, respectively.