Measuring Thiols in Single Cultivar South African Red Wines Using 4,4-Dithiodipyridine (DTDP) Derivatization and Ultraperformance Convergence Chromatography-Tandem Mass Spectrometry

Wine varietal thiols are important contributors to wine aroma. The chemical nature of thiols makes them difficult to measure due to low concentrations, high sensitivity to oxidation, and low ionization. Methods for the measurement of thiols usually consist of multiple steps of sample preparation followed by instrumental measurement. Studies have collected large datasets of thiols in white wine but not in red wine, due to the lack of availability of suitable methods. In this study, for the first time, convergence chromatography was used to measure thiols in red wine at ultratrace levels with improved sensitivity compared to previous methods. Performance parameters (selectivity, linearity, limits of detection, precision, accuracy) were tested to demonstrate the suitability of the method for the proposed application. Red wine thiols were measured in South African Pinotage, Shiraz, and Cabernet Sauvignon wines (n = 16 each). Cultivar differentiation using the thiol profile was demonstrated.

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Impacts of bottle storage on wine flavor and underlying chemistry

10.32469/10355/63370 ◽

2017 ◽

Author(s):

◽

Stephanie Grau

Keyword(s):

Dissolved Oxygen ◽

Red Wine ◽

Accelerated Aging ◽

Dimethyl Disulfide ◽

Vacuum Treatment ◽

White Wine ◽

Significant Loss ◽

Wine Aroma ◽

Low Oxygen ◽

Wine Flavor

Two studies were conducted to address quality degradation and chemical changes, first in wines resealed after opening and second, in wines stored under low oxygen conditions. In the first study, an assortment of strategies for resealing wines were evaluated. Resealing with a vacuum closure resulted in headspace and dissolved oxygen levels that were significantly less than all other closure types at the end of storage. Vacuum treatment had no deleterious impacts on white wine aroma, but resulted in significant decreases in several compounds in red wine. In white wine treatments which had significantly higher final dissolved oxygen than the controls, significant reductions in bound SO2 were observed after three days of storage, but no significant loss of free SO2 was apparent. In some red wine treatments exposed to similar headspace oxygen, significant loss of free SO2 occurred without changes in bound SO2. In the second study, a convenient accelerated aging assay was developed to characterize the potential for H2S to accumulate in wine during low oxygen bottle storage. Wine samples were incubated at 80[degrees]C for 1 hour, then H2S was measured using gas detection tubes. The assay was used to evaluate H2S emergence from hypothesized precursor compounds in three wines. Significant increases in H2S production after accelerated aging were found in at least one wine spiked with cysteine, sulfur dioxide, methyl thioacetate, dimethyl disulfide, and a model quinone-H2S adducts mixture, but not in wines with added glutathione.

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Multivariate spectroscopy for targeting phenolic choreography in wine with A-TEEMTM and NMR crosscheck non-targeted metabolomics

BIO Web of Conferences ◽

10.1051/bioconf/20191502006 ◽

2019 ◽

Vol 15 ◽

pp. 02006 ◽

Cited By ~ 2

Author(s):

J.E. Herbert-Pucheta ◽

G. Padilla-Maya ◽

D. Milmo-Brittinham ◽

D. Lojero ◽

A.M. Gilmore ◽

...

Keyword(s):

Red Wine ◽

High Sensitivity ◽

Proton Nuclear Magnetic Resonance ◽

Targeted Metabolomics ◽

Fluorescence Excitation ◽

Specific Chemical ◽

Excitation Emission Matrix ◽

Chemical Conditions ◽

First Time

Present work comprises the use of different multivariate spectroscopic methods for tracking novel metabolomics signatures related to red wine chemistry. It is presented for the first time the proton nuclear magnetic resonance metabolomics fingerprint of a monovarietal Mexican Merlot, obtained with acquisition improvements recently proposed to the OIV Methods of Analysis sub-commission. Effective multi-presaturation solvent schemes have revealed a rich (poly)-phenolics aromatic region, so far not exploited for wine-fingerprinting or – targeted profiling routines. It is presented as well for the first time the use of simultaneous absorbance-transmission and fluorescence excitation-emission matrix “push-one-bottom” method (A-TEEMTM) at specific chemical conditions for a rapid, effective and high-sensitivity characterization of phenolic choreography in wines, as novel observables to quantify oenological practices and aging.

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Fast and Reliable Multiresidue Analysis of Aromas in Wine by Means of Gas Chromatography Coupled with Triple Quadrupole Mass Spectrometry

Analytica ◽

10.3390/analytica2020005 ◽

2021 ◽

Vol 2 (2) ◽

pp. 38-49

Author(s):

Ettore Guerriero ◽

Massimo Iorizzo ◽

Marina Cerasa ◽

Ivan Notardonato ◽

Bruno Testa ◽

...

Keyword(s):

Direct Injection ◽

Headspace Analysis ◽

White Wine ◽

Quadrupole Mass ◽

Multiresidue Analysis ◽

Liquid Liquid Extraction ◽

Volatile Organic ◽

Steel Tank ◽

First Time

The paper would like to show a direct injection into GC-MS/QqQ for the determination of secondary aromas in white wine samples fermented in two different ways. The procedure has been compared with more traditional methods used in this field, i.e., headspace analysis and liquid–liquid extraction. The application of such direct injection, for the first time in the literature, allows us to analyze Volatile Organic Compounds (VOCs) in the range 0.1–100 µg mL−1, with Limits of Detection (LODs) and Limits of Quantification (LOQs) between 0.01–0.05 µg mL−1 and 0.03–0.09 µg mL−1, respectively, intraday and interday below 5.6% and 8.5%, respectively, and recoveries above 92% at two different fortification levels. The procedure has been applied to real wine samples: it evidences how the fermentation in wood (cherry) barrel yields higher VOC levels than ones in wine fermented in steel tank, causing production of different secondary aromas and different relative flavors.

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All-Dielectric Metasurface for Sensing Microcystin-LR

Electronics ◽

10.3390/electronics10111363 ◽

2021 ◽

Vol 10 (11) ◽

pp. 1363

Author(s):

Binze Ma ◽

Ao Ouyang ◽

Juechen Zhong ◽

Pavel A. Belov ◽

Ravindra Kumar Sinha ◽

...

Keyword(s):

Quality Factor ◽

Bound States ◽

High Sensitivity ◽

Concentration Limit ◽

Specific Recognition ◽

Low Concentrations ◽

Freshwater Bodies ◽

Toxic Pollutant ◽

Small Change ◽

Dielectric Metasurface

Sensing Microcystin-LR (MC-LR) is an important issue for environmental monitoring, as the MC-LR is a common toxic pollutant found in freshwater bodies. The demand for sensitive detection method of MC-LR at low concentrations can be addressed by metasurface-based sensors, which are feasible and highly efficient. Here, we demonstrate an all-dielectric metasurface for sensing MC-LR. Its working principle is based on quasi-bound states in the continuum mode (QBIC), and it manifests a high-quality factor and high sensitivity. The dielectric metasurface can detect a small change in the refractive index of the surrounding environment with a quality factor of ~170 and a sensitivity of ~788 nm/RIU. MC-LR can be specifically identified in mixed water with a concentration limit of as low as 0.002 μg/L by a specific recognition technique for combined antigen and antibody. Furthermore, the demonstrated detection of MC-LR can be extended to the identification and monitoring of other analytes, such as viruses, and the designed dielectric metasurface can serve as a monitor platform with high sensitivity and high specific recognition capability.

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The Double Face of Ketamine—The Possibility of Its Identification in Blood and Beverages

Molecules ◽

10.3390/molecules26040813 ◽

2021 ◽

Vol 26 (4) ◽

pp. 813

Author(s):

Magdalena Świądro ◽

Paweł Stelmaszczyk ◽

Irena Lenart ◽

Renata Wietecha-Posłuszny

Keyword(s):

Date Rape ◽

Signal To Noise Ratio ◽

High Sensitivity ◽

Heroin Addiction ◽

Assisted Extraction ◽

Low Concentrations ◽

High Concentrations ◽

Rosé Wine ◽

Tof Ms

The purpose of this study was to develop and validate a high-sensitivity methodology for identifying one of the most used drugs—ketamine. Ketamine is used medicinally to treat depression, alcoholism, and heroin addiction. Moreover, ketamine is the main ingredient used in so-called “date-rape” pills (DRP). This study presents a novel methodology for the simultaneous determination of ketamine based on the Dried Blood Spot (DBS) method, in combination with capillary electrophoresis coupled with a mass spectrometer (CE-TOF-MS). Then, 6-mm circles were punched out from DBS collected on Whatman DMPK-C paper and extracted using microwave-assisted extraction (MAE). The assay was linear in the range of 25–300 ng/mL. Values of limits of detection (LOD = 6.0 ng/mL) and quantification (LOQ = 19.8 ng/mL) were determined based on the signal to noise ratio. Intra-day precision at each determined concentration level was in the range of 6.1–11.1%, and inter-day between 7.9–13.1%. The obtained precision was under 15.0% (for medium and high concentrations) and lower than 20.0% (for low concentrations), which are in accordance with acceptance criteria. Therefore, the DBS/MAE/CE-TOF-MS method was successfully checked for analysis of ketamine in matrices other than blood, i.e., rose wine and orange juice. Moreover, it is possible to identify ketamine in the presence of flunitrazepam, which is the other most popular ingredient used in DRP. Based on this information, the selectivity of the proposed methodology for identifying ketamine in the presence of other components of rape pills was checked.

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Characterisation of Extracts Obtained from Unripe Grapes and Evaluation of Their Potential Protective Effects against Oxidation of Wine Colour in Comparison with Different Oenological Products

Foods ◽

10.3390/foods10071499 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1499

Author(s):

Giovanna Fia ◽

Ginevra Bucalossi ◽

Bruno Zanoni

Keyword(s):

Antioxidant Activity ◽

Red Wine ◽

Waste Product ◽

Natural Antioxidants ◽

White Wine ◽

Small Scale ◽

Protective Effects ◽

White Wines ◽

Accelerated Oxidation ◽

Wine Colour

Unripe grapes (UGs) are a waste product of vine cultivation rich in natural antioxidants. These antioxidants could be used in winemaking as alternatives to SO2. Three extracts were obtained by maceration from Viognier, Merlot and Sangiovese UGs. The composition and antioxidant activity of the UG extracts were studied in model solutions at different pH levels. The capacity of the UG extracts to protect wine colour was evaluated in accelerated oxidation tests and small-scale trials on both red and white wines during ageing in comparison with sulphur dioxide, ascorbic acid and commercial tannins. The Viognier and Merlot extracts were rich in phenolic acids while the Sangiovese extract was rich in flavonoids. The antioxidant activity of the extracts and commercial tannins was influenced by the pH. In the oxidation tests, the extracts and commercial products showed different wine colour protection capacities in function of the type of wine. During ageing, the white wine with the added Viognier UG extract showed the lowest level of colour oxidation. The colour of the red wine with the UG extract evolved similarly to wine with SO2 and commercial tannins. The obtained results indicated that natural and healthy UG extracts could be an interesting substitute for SO2 during wine ageing.

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Implications for the age of South African Devonian rocks in which Tropidoleptus (Brachiopoda) has been found

Geological Magazine ◽

10.1017/s0016756800025024 ◽

1983 ◽

Vol 120 (1) ◽

pp. 51-58 ◽

Cited By ~ 22

Author(s):

A. J. Boucot ◽

C. H. C. Brunton ◽

J. N. Theron

Keyword(s):

South Africa ◽

North America ◽

South African ◽

Early Carboniferous ◽

Fossil Plants ◽

Geological Time ◽

Marine Sedimentation ◽

History Of ◽

Near Shore ◽

First Time

SummaryThe Devonian brachiopod Tropidoleptus is recognized for the first time in South Africa. It is present in the lower part of the Witteberg Group at four widely separated localities. Data regarding the stratigraphical range of the genus elsewhere, combined with information on recently described fossil plants and vertebrates from underlying strata of the upper Bokkeveld Group, suggest that a Frasnian or even Givetian age is reasonable for the lower part of the Witteberg Group. The recognition of Tropidoleptus in a shallow water, near-shore, molluscan association, at the top of the South African marine Devonian sequence, is similar to its occurrence in Bolivia, and suggests a common Malvinokaffric Realm history of shallowing, prior to later Devonian or early Carboniferous non-marine sedimentation. It is noteworthy that Tropidoleptus is now known to occur in ecologically suitable environments around the Atlantic, but is absent from these same environments in Asia and Australia. Tropidoleptus is an excellent example of dispersal in geological time — first appearing in northern Europe and Nova Scotia, then elsewhere in eastern North America and North Africa, followed by South America and South Africa, while continuing in North America.

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Self-Rated Aversion to Taste Qualities and the PROP Taster Phenotype Associate with Alcoholic Beverage Intake and Preference

Beverages ◽

10.3390/beverages7020037 ◽

2021 ◽

Vol 7 (2) ◽

pp. 37

Author(s):

Gary J. Pickering ◽

Margaret K. Thibodeau

Keyword(s):

Alcohol Consumption ◽

Red Wine ◽

Alcoholic Beverage ◽

Likert Scale ◽

White Wine ◽

Sensory Attributes ◽

Taste Perception ◽

Alcoholic Beverages ◽

Convenience Sample ◽

Beverage Type

Consumers often identify “taste” as an important factor when selecting alcoholic beverages. Although it is assumed that reduced alcohol consumption in PROP super-tasters is due to a greater dislike of the nominally aversive sensations that they experience more intensely (e.g., bitterness) when compared to PROP non-tasters, this question has not been specifically asked to them. Therefore, we examined consumers’ self-reported aversion towards specific sensory attributes (bitter, hot/burn, dry, sour, sweet, carbonation) for four alcoholic beverage types (white wine, red wine, beer, spirits) using a convenience sample of U.S. wine consumers (n = 925). Participants rated 18 statements describing different combinations of sensory attributes and alcoholic beverages on a 5-point Likert scale (e.g., Beer tastes too bitter for me). Individuals who tended to agree more strongly with the statements (i.e., they were more averse; p(F) < 0.05) tended to (i) consume less of all beverage types, (ii) consume a higher proportion of white wine (p(r) < 0.05), and (iii) were more likely to be female or PROP super-tasters. The results suggest that self-reported aversion to specific sensory attributes is associated with not only lower overall intake of alcoholic beverages, but also a shift in the relative proportions of beverage type consumed; a key finding for studies investigating how taste perception impacts alcohol consumption.

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Determination of Total Carbohydrates in Wine and Wine-Like Beverages by HPLC with a Refractive Index Detector: First Action 2013.12

Journal of AOAC International ◽

10.5740/jaoacint.13-320 ◽

2014 ◽

Vol 97 (2) ◽

pp. 498-505 ◽

Cited By ~ 2

Author(s):

Steve Kupina ◽

Mark Roman ◽

D Anderson ◽

S Bhandari ◽

M S Cardozo ◽

...

Keyword(s):

Refractive Index ◽

Reference Material ◽

Organic Acids ◽

Red Wine ◽

Collaborative Study ◽

Ion Exchange Resin ◽

White Wine ◽

Negative Control ◽

Total Carbohydrates

Abstract An international collaborative study was conducted of an HPLC-refractive index (RI) detector method for the determination of the combined amounts of sugars, glycerol, organic acids, and phenolic compounds in wines and wine-like beverages. Nine collaboratinglaboratories representing major winery, contract laboratories, and government laboratories tested eight different materials as blind duplicates using the proposed method. Sample materials included red and white wines, port, wine cooler, and nonalcoholic wine. One material was a negative control, and one material was a reference material. Samples were either treated with an ion-exchange resin to remove interferingorganic acids prior to analysis or left untreated toinclude organic acids and phenolics. Red wine samples were treated with polyvinylpolypyrrolidone to remove potential interferences from phenolics prior to analysis. The HPLC analyses were performed on a Bio-Rad Fast Acid Analysis Column using RI detection. Reproducibility (RSDR) for untreated samples(sugars + phenolics + organic acids) ranged from 6.6% for Titrivin AA4 reference material to 11.0% for dry red wine. RSDR for treated samples (sugars only) ranged from 6.8% for white zinfandel to 18.9% for dry white wine. RSDR for treatedsamples (sugars only) + glycerol ranged from 6.4% for white zinfandel to 19.8% for dry red wine. Based on these results, the method was adopted as Official First Action status for determination of total carbohydrates in wine and wine-like beverages.

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UHPLC/ESI-MS/MS Determination of 187 Pesticides in Wine

Journal of AOAC International ◽

10.5740/jaoacint.15-0265 ◽

2016 ◽

Vol 99 (2) ◽

pp. 539-557 ◽

Cited By ~ 9

Author(s):

Jian Wang ◽

Wendy Cheung

Keyword(s):

Measurement Uncertainty ◽

Electrospray Ionization ◽

Pesticide Residues ◽

Red Wine ◽

White Wine ◽

Tandem Ms ◽

Fast Method ◽

Intermediate Precision ◽

Method Performance ◽

Standard Calibration

Abstract This paper presents an ultra HPLC/electrospray ionization-tandem MS method to determine pesticides in wine. We adopted the quick, easy, cheap, effective, rugged, and safe (QuEChERs) method for extraction and used core-shell column to achieve ultra-HPLC to develop and validate a simple and fast method to analyze 187 pesticide residues in red and white wine samples. Pesticide residues were extracted from wine samples using QuEChERS. Ultra HPLC/electrospray ionization-tandem MS quantification was achieved using matrix-matched standard calibration curves with isotopically labeled standards or a chemical analogue as internal standards with an analytical range from 5.0 to 500.0 μg/L. The method performance characteristics that included overall recovery, intermediate precision, and measurement uncertainty were evaluated according to a nested experimental design. Generally, 98.4% (in red wine) and 96.8% (in white wine) of the pesticides had recoveries between 71 and 120%; 98.9% (in red wine) and 99.5% (in white wine) of the pesticides had the intermediate precision ≤20%; and 99.5% (in red wine) and 98.4% (in white wine) of the pesticides had measurement uncertainty ≤50%.

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