Red Wine Samples Research Articles

Robust and facile label-free colorimetric aptasensor for ochratoxin A detection using aptamer-enhanced oxidase-like activity of MnO2 nanoflowers

Ochratoxin A (OTA) is a powerful mycotoxin that can cause severe damage to human health, and its detection has attracted considerable attention in the field of food science. We present a robust and facile label-free colorimetric aptasensor for OTA detection using the aptamer-enhanced oxidase-like activity of MnO2 nanoflowers. The catalytic activities of the nanozymes could be improved by adsorption of the aptamers onto the MnO2 nanoflowers due to the increased affinity of the nanoflowers for the chromogenic substrate. The linear range for OTA detection varied from 0.05 to 33.35 ng/mL with a detection limit of 0.069 ng/mL. The limit of detection of the proposed strategy is equivalent to or even better than those of several previous methods. Moreover, the colorimetric aptasensor exhibited good specificity and stability for the analysis of OTA in wheat flour and red wine samples. Therefore, this method appears to have promising applications in the detection of mycotoxins.

Instrument comparability of non-targeted UHPLC-HRMS for wine authentication

Instrument comparability is a major prerequisite for the harmonization of non-targeted analytical approaches for food authentication. While non-targeted liquid chromatography coupled with mass spectrometry (LC-MS) is a powerful and widely used technique in authenticity studies, inter-laboratory or instrument comparison exercises are rare. For the first time, in the present study a comparison of two LC-MS platforms using identical setups and conditions except for the mass spectrometer (Orbitrap Q Exactive™ Focus vs. Plus) was carried out in order to assess the impact of instrumental differences on the classification of grape varieties in wine. A set of 201 red and white wine samples comprising 10 grape varieties was analyzed with both platforms and subjected to multivariate statistical analysis. Using unsupervised and supervised methods, the same correlation pattern between samples was observed with both platforms. Partial Least Squares – Discriminant Analysis (PLS-DA) classification models achieved comparable accuracies in the internal validation (90–95%). The percentage of common discriminating features was about 46–69% between both platforms. The common features were used to merge data from both instruments and joint PLS-DA models produced excellent results. The prediction of data from one platform with the model from the other platform, as well as a model using data from both platforms, resulted in correct classification rates of 92–98%. Putative identification of common features was performed to determine potential marker substances for grape varieties. With this study, a first step towards harmonization of non-targeted LC-MS approaches for wine authentication is taken, advancing their potential application in official food control.

A Novel Voltammetric Electronic Tongue Based on Nanocomposites Modified Electrodes for the Discrimination of Red Wines from Different Geographical Origins

A novel voltammetric electronic tongue (VE-tongue) system based on three nanocomposites modified working electrodes was used for the discrimination of red wine from different geographical origins. The three types of modified working electrodes were fabricated to detect glucose (Glu), tartaric acid (TA), and non-specific flavor information in a red wine sample, respectively. The electrochemical properties of three electrodes were tested by cyclic voltammetric method, and pH, accumulation time, and scan rates were optimized for Glu and TA sensors. Scanning electron microscopy (SEM), X-ray proton spectrum (XPS), and X-ray diffraction (XRD) were used for the characterization of modified materials. This sensor array was then applied to identify four kinds of red wines from different geographical origins, and the multi-frequency and potential steps (STEP) method was used to obtain flavor information regarding rice wines. The classification ability of this VE-tongue system was evaluated by using partial least squares (PLS) regression and principal component analysis (PCA), while back propagation neural network (BPNN), random forest (RF), support vector machines (SVM), deep neural network (DNN), and K-nearest neighbor (KNN) were used for the prediction. The results showed that PCA could explain about the 95.7% of the total variance, and BPNN performed best in the prediction work (the prediction accuracy was 95.8%). Therefore, the VE-tongue system with BPNN was chosen to effectively discriminate red wines from different geographical origins, and the novel VE-tongue aiming at red wine discrimination with high accuracy and lower cost was established.

Amperometric Sensor for Selective On-Site Analysis of Free Sulfite in Wines.

Accurate and rapid on-site analysis of free SO2 content is crucial in the process of winemaking from a producer and consumer perspective. Herein, we present an amperometric sensor based on commercially available screen-printed electrodes coupled with an electrochemical oxygen filter. The developed amperometric method gave a linear response in a concentration range up to 200 mg L-1 with a limit of quantification of 7.5 mg L-1. The applicability of the developed sensor was successfully tested on 27 white and red wine samples and compared to the Ripper method (iodometry) that is a standard procedure for free SO2 determination. The sensor exhibits similar precision and accuracy but shows no interference from oxidizable species such as ascorbic acid, which is a major advantage over iodometric titration. The performance of the sensor was in addition positively evaluated during on-site analysis in a winery.

Correlation of Wine’s Main Components’ Concentration with the Density of Model Aqueous Solutions and Wine Samples

Density is an important physical property, affecting wine mouthfeel, while it can also be used for monitoring alcoholic fermentation in winemaking. Aim of this study was to elucidate the correlation of ethanol, glucose/fructose, glycerol and tartaric acid on the density of model aqueous solutions and Greek wine samples. Various model aqueous solutions were prepared and density was measured at 20 ˚C. Density of dry white and red wine samples was also measured. A linear regression analysis was performed and theoretical fermentation monitoring curves by density measurement were obtained. The resulting models presented a coefficient of determination over 97.3%. Tartaric acid was found to increase density the most, followed by glucose and glycerol, whereas ethanol decreased density. The knowledge of the correlation of the concentration of each wine component with density may be beneficial to quantitative analysis of wine and to optimizing wine mouthfeel.

Electrochemically activated copper nitroprusside as a catalyst for sensing of carcinogenic acetaldehyde in red wine

Acetaldehyde (AcH) is a carcinogenic, neurotoxic and genotoxic volatile organic compound present in beverages and pose hazardous effects on human health. Herein, we report electrochemically activated copper nitroprusside (CuNPr)-based sensor for the ultra-trace detection of AcH. CuNPr was synthesized by simple co-precipitation method and its physicochemical properties were characterized using spectroscopy and microscopy techniques. CuNPr-modified glassy carbon electrode (CuNPr/GCE) has been electrochemically activated prior to deploying for AcH sensing. The influence of electrochemical activation and supporting electrolytes (LiCl, NaCl, KCl, CsCl, KNO3, Na2HPO4/NaH2PO4, K2HPO4/KH2PO4) have been investigated. A better sensitivity of the sensor was obtained with potassium phosphate (K2HPO4/KH2PO4, pH 7.4) buffer. The electrochemical oxidation of AcH to acetate ions by CuNPr has been studied using in-situ spectroelectrochemical (UV absorption and Raman spectroscopy) analyses. Under optimized differential pulse voltammetric conditions, electrochemically activated CuNPr/GCE exhibited a wide linear range (2.5 × 10−8 – 2.5 × 10−1 M) with a limit of detection towards AcH as low as 41 × 10−8 M. The developed CuNPr/GCE sensor was employed for the sensing of AcH in undiluted commercial red wine sample and found to have good stability and anti-interference ability towards various co-existing ions in undiluted red wine.

Assessment of Bioactive Compounds in Red Wines Available for Purchase in Latvia

Abstract Moderate consumption of wine is associated with positive health effects. Red wine contains more polyphenolic compounds than white wine, so it is considered healthier. The aim of the study was to determine the concentration of bioactive compounds of red grape and berry wines available for purchase in Latvia. A selection of 15 red grape and berry wines purchased in Latvian supermarkets were analysed. The total phenol concentration was determined using the Folin-Ciocalteu spectrophotometric method with minor modifications. Total flavonoid concentration was determined using the colorimetric flavonoid determination method. Antiradical activity was determined using the DPPH (2,2-diphenyl-1-picrylhydraziyl) reagent and ABTS (2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonate) radical cation determination method. The results show that the analysed red wine samples can be divided into five clusters according to the concentration of total phenols, flavonoids, and antiradical activity. Cluster 1 separately divided Latvian black chokeberry wine, with high total phenol concentration (TPC) and total flavonoid concentration (TFC), high antiradical activity via the DPPH method, and relatively low antiradical activity via ABTS method. Cluster 4 combined red wines with medium TPC, high TFC and high antiradical activity via both DPPH and ABTS methods, and included grape wines from different countries of origin. Cluster 5 combined red wines with high TPC, medium TFC, and medium antiradical activity via both DPPH and ABTS methods.

Fabrication of wurtzite ZnO embedded functionalized carbon black as sustainable electrocatalyst for detecting endocrine disruptor trichlorophenol

The edifice of proficient and patronizing nanoshaped affordable catalysts for accurate detection of pharmaceutical drugs and nitroaromatic compounds that gained substantial courtesy by the researchers. By the way, we untrue wurtzite zinc oxide encapsulated functionalized carbon black (ZnO/f-CB) nanocomposite via eco benign coprecipitation method and utilized it as affordable electrocatalyst for the detection of endocrine disruptor 2,4,6-Trichlorophenol (TCP). The physical and crystalline nature of the as-synthesized nanocomposite was characterized by XRD, Raman, FT-IR, SEM, EDX and Elemental mapping analysis. Noticeably, the ZnO/f-CB modified SPCE displays a superior dynamic response range 0.01 to 435 μM, enlarged sensitivity 1.07 μA/μM·1 cm2, low-level of detection 0.010 nM with excellent selectivity and reproducibility towards TCP detection. In addition, the modified electrode retains outstanding repeatability and storage capability properties. Conspicuously, the ZnO/f-CB proposed sensor can detect TCP in tap water and red wine samples thru large retrievals, signifying its viability for real-time monitoring. Our outcomes denote ZnO/f-CB as a rapid and promising platform for the determination of chloroaromatic compounds and biological samples. These results endorse an innovative proposal for synthesizing newly functionalized nanomaterials.

Polyaniline Nanofibers-Embedded Gold Nanoparticles Obtained by Template-Free Procedure with Immobilization Prospects.

In this work, template-free nanostructured conducting polymers (nCPs)-embedded gold nanoparticles (AuNPs) from aniline, thiophene and 3,4-ethylenedioxythiophene have been prepared via a one-pot sonochemical method. The synthesis of the nanocomposite (nCPs-AuNPs) was achieved in a short period of time (5–10 min), by applying high-energy ultrasound to an aqueous mixture of a CP precursor monomer and KAuCl4, in the presence of LiClO4 as dopant. The synthesis process is simpler, greener and faster in comparison to other procedures reported in the literature. Remarkably, bulk quantities of doped polyaniline PANI-AuNPs nanofibers were obtained. Subsequently, they were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR), as well as by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). PANI-AuNPs nanofibers were also employed as immobilization matrix for a benchmark enzyme, glucose oxidase (GOX). Finally, glucose was determined in real samples of white and red wines by using the so-obtained GOX-PANI-AuNPs/Sonogel-Carbon biosensor, providing outstanding recoveries (99.54%). This work may offer important insights into the synthesis of nanostructured conducting polymers and also stimulates the exploration of the applications of these nanocomposites, especially in research fields such as (bio)sensors, catalysis and composite materials.

Alcoholic Fermentation Monitoring and pH Prediction in Red and White Wine by Combining Spontaneous Raman Spectroscopy and Machine Learning Algorithms

In the following study, total sugar concentrations before and during alcoholic fermentation, as well as ethanol concentrations and pH levels after fermentation, of red and white wine grapes were successfully predicted using Raman spectroscopy. Fluorescing compounds such as anthocyanins and pigmented phenolics found in red wine present one of the primary limitations of enological analysis using Raman spectroscopy. Unlike the spontaneous Raman effect, fluorescence is a highly efficient process and consequently emits a much stronger signal than spontaneous Raman scattering. For this reason, many enological applications of Raman spectroscopy are impractical as the more subtle Raman spectrum of any red wine sample is in large part masked by fluorescing compounds present in the wine. This work employs a simple extraction method to mitigate fluorescence in finished red wines. Ethanol and total sugars (fructose plus glucose) of wines made from red (Cabernet Sauvignon) and white (Chardonnay, Sauvignon Blanc, and Gruner Veltliner) varieties were modeled using support vector regression (SVR), partial least squares regression (PLSR) and Ridge regression (RR). The results, which compared the predicted to measured total sugar concentrations before and during fermentation, were excellent (R2SVR = 0.96, R2PLSR = 0.95, R2RR = 0.95, RMSESVR = 1.59, RMSEPLSR = 1.57, RMSERR = 1.57), as were the ethanol and pH predictions for finished wines after phenolic stripping with polyvinylpolypyrrolidone (R2SVR = 0.98, R2PLSR = 0.99, R2RR = 0.99, RMSESVR = 0.23, RMSEPLSR = 0.21, RMSERR = 0.23). The results suggest that Raman spectroscopy is a viable tool for rapid and trustworthy fermentation monitoring.

Centri‐Voltammetric GSH Detection with PDI‐C4SH as a Carrier Material

AbstractIn this study, we developed a centri‐voltammetric electrochemical sensor for glutathione (GSH) detection. For this purpose, N,N′‐2‐octyloxy‐1‐methyl‐2‐oxoethyl)‐(‐2,4‐thiolbutyloxy)‐1‐methyl‐2‐oxoethyl)‐3,4 : 9,10‐perylenetetracarboxyldiimide (PDI‐C4SH) molecule was used as a carrier molecule for the first time. This molecule, interacted with the thiol ends of GSH and formed a disulfide bridge. By this way, PDI‐C4SH improved the accumulation of GSH onto the electrode surface and increased the sensitivity of the detection protocol. All the electrochemical measurements were carried out with differential pulse voltammetry by using a carbon paste electrode. The linear response was obtained in the range of 0.05 mM and 5 mM for GSH concentration (R2=0.9966) while limit of detection value was calculated as 0.017 mM. For the sample application experiments, developed system was applied to the determination of GSH in red wine samples by using the standard addition method, and an acceptable recovery value of 99.03 % was obtained.

Graphene aerogel decorated with MoS2 sheets: an efficient electrochemical sensing platform for caffeic acid in red wine sample

As a typical two-dimensional (2D) transition metal disulfide, molybdenum disulfide (MoS 2 ) shows good electrocatalytic activity, and is considered as a promising sensing material due to its adequate exposed active edges. However, 2D sheet-like structural MoS 2 tends to aggregate, resulting in a decreased specific surface area. In addition, the poor electronic conductivity of MoS 2 limits the electrochemical application. To address these issues, herein, graphene aerogel (GA), with a three-dimensional (3D) nanoarchitecture consisting of a large specific surface area, rapid electron transfer, and excellent electrocatalytic activity, has been employed as a novel framework support for MoS 2 . Through a facile one-step hydrothermal technique, the peeled MoS 2 sheets were incorporated into the GA network. The MoS 2 /GA composite was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The composite combined the excellent electrical conductivity and huge effective surface area of GA with the high catalytic activity of the MoS 2 nanosheets. Due to these advantages, the MoS 2 /GA composite was applied as an electrochemical sensing platform for caffeic acid (CA) detection. The sensor performed good selectivity, wide linear range (1.0 nM-10.0 μM), and low limit of detection (LOD, 0.3 nM). Furthermore, the designed sensor represented good reproducibility and stability, and was successfully applied for detecting CA in red wine samples.

FIA–HRMS fingerprinting subjected to chemometrics as a valuable tool to address food classification and authentication: Application to red wine, paprika, and vegetable oil samples

The rise of food fraud practices, affecting a wide variety of goods and their specific characteristics (e.g., quality or geographical origin), demands rapid high-throughput analytical approaches to ensure consumers protection. In this context, this study assesses flow injection analysis coupled to high-resolution mass spectrometry (FIA–HRMS), using a fingerprinting approach and combined with chemometrics, to address four food authentication issues: (i) the geographical origin of three Spanish red wines, (ii) the geographical origin of three European paprikas, (iii) the distinction of olive oil from other vegetable oils and (iv) the assessment of its quality category. In each case, negative and positive ionisation FIA–HRMS fingerprints, and two different data fusion strategies, were evaluated. After external validation, excellent classification accuracies were reached. Moreover, high-resolution mass spectrometry (HRMS) allowed sample matrices characterisation by the putative identification of the most common ions.

HPLC-potentiometric method for determination of biogenic amines in alcoholic beverages: A reliable approach for food quality control

Determination of ten biogenic amines in alcoholic beverages by HPLC coupled to a potentiometric detector for food quality control is herein presented. Biogenic amines were separated by ion-pair chromatography on a C18 column using a gradient mobile phase of acetic acid, acetonitrile, and butane-sulfonic acid. Detection was accomplished by a miniaturized amine-selective electrode. The method was validated following ICH and Eurachem guidelines. Linear regression models provided R2 values from 0.9870 ± 0.0019 to 0.9991 ± 0.0014 for tyramine and cadaverine, respectively. Detection and quantification limits depend on the molecular weight of BAs, ranging from 9.3 to 60.5 and from 31.1 to 202.3 µg L−1 for methylamine and spermine, respectively. Repeatability and intermediate precision showed RSD values lower than 5.8 and 8.3%, respectively. Accuracy of assays yielded recovery values from 86.4 to 109.9%. The biogenic amines content in red wine, white wine, and beer samples were 7.54, 5.24, and 4.58 mg L-1, respectively.

Влияние спиртового и яблочно-молочного брожения на содержание биогенных аминов в винах

Introduction. The concentration of biogenic amines is an important indicator of the safety of food products, especially winemaking. In grape wines, this concentration varies widely depending on the grape variety, its microbiological state, processing technology, the race of yeast and bacteria of malolactic fermentation, conditions of alcoholic and malolactic fermentation, etc. This research is aimed at determining the effect of the production technology of dry white and red wines on the concentration of biogenic amines.
 Study objects and methods. The mass concentration of biogenic amines was determined by the method of high-performance capillary electrophoresis using a Kapel 105R in laboratory-obtained samples of dry white wine from the Chardonnay grape variety and table dry red wine from the Cabernet-Sauvignon grape variety.
 Results and discussion. The dry white wine samples revealed high concentrations of tyramine (1.12 mg/dm³), phenylethydamine (0.58 mg/dm³), and histamine (0.57 mg/dm³), while the red wine samples demonstrated tyramine (0.62 mg/dm³), histamine (0.45 mg/dm³), putrescine (0.43 mg/dm³), and cadaverine (0.38 mg/dm³). The white wine samples had optimal pH values (3.2–3.6) with minimal formation of biogenic amines. The red wine samples, especially those obtained by heat treatment, had a lower concentration of biogenic amines, especially volatile biogenic amines, i.e. methylamine and phenylethylamine. The greatest formation of biogenic amines occurred during the acid reduction process: under the effect of enzymes of malolactic bacteria, biogenic amines formed as a result of decarboxylation of amino acids. 
 Conclusion. The technology of production of table dry white and red wines affects the concentration of biogenic amines. To reduce the level of biogenic amines in the finished product, each stage of vinification has to be controlled, especially the stages of fermentation and acid reduction (temperature and pH). The race of yeast and lactic acid bacteria cannot include those that produce biogenic amines or introduce them in minimal quantities.

Natural Contaminants in Wines: Determination of Biogenic Amines by Chromatographic Techniques.

Biogenic amines (BAs) are natural contaminants of wine that originate from decarboxylase microorganisms involved in fermentation processes. The primary relevance of biogenic amines in food could have both toxic effects on consumers’ health (i.e., allergic reactions, nausea, tremors, etc.), if present at high concentrations, and concurrently it can be considered as a remarkable indicator of quality and/or freshness. Therefore, the presence of nine biogenic amines [Tryptamine (TRP), ß-phenylethylamine (ß-PEA), putrescine (PUT), cadaverine (CAD), histamine (HIS), serotonin (SER), tyramine (TYR), spermidine (SPD), and spermine (SPM)] was investigated in red and white wine samples, which differed in the winemaking processes. The qualitative-quantitative determination of BAs was carried out by chromatographic methods (HPLC-UV/Vis and LC-ESI-MS). The analysis showed that both winemaking processes had all the nine BAs considered in the study at different amounts. Data showed that red wines had a higher concentration of PUT (10.52 mg L−1), TYR (7.57 mg L−1), and HIS (6.5 mg L−1), the BAs most involved in food poisoning, compared to white wines, probably related to the different type of fermentation (alcoholic and malolactic).

A highly sensitive and selective fluorescent probe for tracking hydrogen sulfide in red wine

AbstractA novel fluorescent H2S probe (LODNBS) composed of 2,4‐dinitrobenzenesulfonyl (DNBS) units was designed and synthesized. The DNBS units not only blocked PET and ICT effects, but also triggered H2S‐mediated thiolysis to cause the fluorescence changes. Probe LODNBS performed excellent sensitivity and selectivity for H2S, strong fluorescence enhancement (65‐fold), low detection limit (72 nM) and real‐time response (within 5 min). The sensing mechanism of LODNBS towards H2S was proposed and verified by ESI‐MS and 1H NMR analysis. Under a UV lamp, the fluorescence color changes could be easily detected by the naked eye. In addition, the probe LODNBS could track H2S in red wine samples with high accuracy and good recovery, and has practical value in food analysis.

Direct quantification of red wine phenolics using fluorescence spectroscopy with chemometrics

Phenolic compounds are secondary metabolites known to play crucial roles in important chemical reactions impacting the mouthfeel, colour and ageing potential of red wine. Their complexity has resulted in a number of advanced analytical methods, which often prevent routine phenolic analysis in winemaking. Fluorescence spectroscopy could be an alternative to current spectrophotometric techniques and its combination with chemometrics was investigated for its suitability in directly quantifying phenolic content of unaltered red wine and fermenting samples. Front-face fluorescence was optimised and used to build predictive models for total phenols, total condensed tannins, total anthocyanins, colour density and polymeric pigments. Machine learning algorithms were used for model development. The most successful models were built for total phenols, total condensed tannins and total anthocyanins with coefficient of determination (R2cal) and RMSECV of 0.81, 0.89, 0.80 and 5.71, 104.03 mg/L, 60.67 mg/L, respectively. The validation results showed R2val values of 0.77, 0.8 and 0.77, and RMSEP values of 7.6, 172.37 mg/L and 76.57 mg/L, respectively. A novel approach for the classification of South African red wine cultivars based on unique fluorescent fingerprints was also successful with an overall cross validation score of 0.8. The best classification ability (validation score = 0.93) was shown for the data set containing only fermenting wines for the most widely represented cultivars (>20 samples). This approach may provide a useful tool for authentication and quality control by regulatory bodies.

Magnetic beads-assisted fluorescence aptasensing approach based on dual DNA tweezers for detection of ochratoxin A and fumonisin B1 in wine and corn.

A magnetic beads (MBs)-assisted fluorescence aptasensing approach based on dual DNA tweezers and magnetic separation was established for the detection of ochratoxin A (OTA) and fumonisin B1 (FB1). A dual DNA tweezers structure with four ends linked with fluorophores (FAM, ROX) and quenchers (BHQ1, BHQ2) was designed, and produced the high initial fluorescence signals because of the long spatial distance between FAM and BHQ1, ROX, and BHQ2. Bio-aptamer/anti-aptamer of OTA and bio-aptamer/anti-aptamer of FB1 were respectively annealed to form dsDNA, and immobilized to MBs coated with streptavidin (SA). With the existence of OTA and FB1, OTA and FB1 preferentially bound with their respective bio-aptamers, which made anti-aptamers dissociate from dsDNA coupled on MBs. After magnetic separation, the dissociated anti-aptamers reacted with dual DNA tweezers, respectively, which made DNA tweezers close and the fluorescence was quenched. The linear ranges of approach for OTA and FB1 detection were 0.05-20ng/mL and 0.1-40ng/mL, respectively. The limit of detection for OTA and FB1 was 0.029ng/mL and 0.061ng/mL. The prepared MBs-assisted fluorescence aptasensing approach was applied to detect OTA and FB1 in spiked red wine and corn samples, which showed good recoveries between 92 and 106%.

Astringent Gallic Acid in Red Wine Regulates Mechanisms of Gastric Acid Secretion via Activation of Bitter Taste Sensing Receptor TAS2R4

Red wine is rich in phenolic compounds, which chiefly determine its characteristic taste. One of its major phenolic acid constituents for which an astringency, yet no clear contribution to bitter taste has been reported, is gallic acid (GA). In previous studies, we have demonstrated bitter-tasting constituents to regulate cellular proton secretion (PS) as a key mechanism of gastric acid secretion via activation of bitter taste sensing receptors (TAS2Rs). Here, we hypothesized a contributing role of GA to the red wine-stimulated effect on PS in human gastric tumor cells (HGT-1 cells). Sensory analyses revealed that 10 μM GA as the lowest concentration tested more bitter than tap water, with increasing bitter ratings up to 1000 μM. In HGT-1 cells, the concentration of 10 μM GA evoked the most pronounced effect on PS secretion, either when added to cells as in-water solution or when spiked to a red wine matrix. GA-spiking of Zweigelt and Blaufränkisch red wine samples up to a concentration of 10 μM resulted in an equally stimulated PS, whereas the non-GA-spiked wine samples demonstrated contrary effects on PS, indicating a functional role of GA on PS. Involvement of TAS2R4 in the GA-induced PS was verified by means of an HGT-1 homozygote CRISPR-Cas9 TAS2R4 knockout approach. Moreover, gene expression analyses revealed GA to increase TAS2R4. These results demonstrate a functional role of TAS2R4 in GA-evoked PS as a key mechanism of gastric acid secretion aiding digestion. Moreover, our data provide mechanistic insights, which will help to produce stomach-friendly red wines.