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1.
Food Chem ; 371: 131341, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-34808767

RESUMO

Over the last five years, polysulfides in wine have become a topic of interest. The finding that both yeast and the wine composition could contribute to the formation and evolution of these compounds has prompted several studies, further corroborated by the discovery of a link between polysulfides and H2S release during ageing. In the present study, the accumulation of cysteinylated and glutathionylated polysulfides was followed during fermentation for the first time. Synthetic grape media and Chardonnay juice treated with CuSO4, elemental sulfur or both were fermented, and subsequently analysed using an in-house UHPLC-HRMS method. Differences in polysulfide accumulation were observed between the two media, highlighting the role of the matrix composition. Elemental sulfur, especially when combined with CuSO4, resulted in significantly increased accumulations of polysulfides compared to controls in both media. Polysulfides with longer S-chains generally appeared later in the fermentation, an observation that prompted further questions on these metabolites' formation.


Assuntos
Vitis , Vinho , Fermentação , Saccharomyces cerevisiae , Sulfetos , Vinho/análise
2.
Food Chem ; 366: 130582, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34303205

RESUMO

Leaf removal applied in the upper canopy of modified vertical shooting positioning trellis system has been proposed as an effective strategy to mitigate the adverse effects of global warming on grape and wine quality. In this study, we removed the upper leaves of Cabernet Sauvignon canopy in a semi-arid climate for three consecutive years (2018-2020). About one-third of the whole canopy leaves were removed at the beginning of véraison (LR1) and post-véraison (LR2). All leaf removal treatments included two schemes: (i) leaf removal in the same vines in all vintages to investigate the carry-over effects (1-LR1 and 1-LR2); (ii) leaf removal in different vines in each vintage as repeated experiments among vintages (2-LR1 and 2-LR2). Results showed that leaf removal treatments significantly decreased total soluble solids accumulation in grapes without affecting titratable acidity and pH. LR1 treatments could delay ripening to 6.6 days on average, which was 2.6 days longer than LR2 treatments. LR treatments did not affect the yield but decreased soluble sugar content in canes. Leaves net assimilation rate showed no compensation for the loss of leaves. For phenolic composition, LR treatments increased flavonol concentration in both wines and grapes while had inconsistent effects on anthocyanins and flavanols over three seasons. Principal component analysis (PCA) showed that different LR treatment stages (LR1s vs LR2s) and whether LR in the same vines over consecutive years (1-LRs vs 2-LRs) had limited effects on phenolic profiles. In conclusion, LR in consecutive years at the upper canopy of grapevines was a practical strategy to face global warming in Xinjiang.


Assuntos
Vitis , Vinho , Antocianinas/análise , Flavonóis , Frutas/química , Folhas de Planta/química , Vinho/análise
3.
Food Chem ; 366: 130690, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34343949

RESUMO

Enzymatic-assisted extraction using Flavourzyme® has been demonstrated to be a useful methodology to obtain wine lees (WL) enriched in phenolic compounds and with enhanced antihypertensive activity. Nevertheless, taking into account that Flavourzyme® possess proteolytic activity, the release of bioactive peptides should not be ruled out. In this study, we investigate the presence of antihypertensive peptides in the WL hydrolysate. Peptides were separated into fractions by ultrafiltration and RP-HPLC. Next, peptide identification by nano-HPLC-(Orbitrap)MS/MS was performed in the fractions showing the highest angiotensin-converting enzyme inhibitory (ACEi) activities. Six peptides were identified; three of them showing ACEi (IC50) values lower than 20 µM. The peptide antihypertensive effect was evaluated in spontaneously hypertensive rats at an oral dose of 10 mg/kg bw. Peptides FKTTDQQTRTTVA, NPKLVTIV, TVTNPARIA, LDSPSEGRAPG and LDSPSEGRAPGAD exhibited antihypertensive activity, confirming that they could contribute to the blood pressure-lowering effect of the WL hydrolysate. These peptides have a great potential as functional ingredients to manage hypertension.


Assuntos
Hipertensão , Vinho , Inibidores da Enzima Conversora de Angiotensina , Animais , Anti-Hipertensivos , Hipertensão/tratamento farmacológico , Peptídeos , Hidrolisados de Proteína , Ratos , Espectrometria de Massas em Tandem
4.
J Sci Food Agric ; 102(2): 664-672, 2022 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-34165824

RESUMO

BACKGROUND: The use of indigenous selected starters in winemaking is gaining interest due to certain advantages for the sensory quality of the wine. The present work shows the results of a laboratory experiment in which the influence of selected indigenous yeasts on the colour characteristics of Pinot Noir was studied with the use of high hydroxycinnamate decarboxylase activity yeasts. Pichia guilliermondii ZIM624 and Wickerhamomyces anomalus S138 yeasts were used in sequential fermentation with two strains of Saccharomyces cerevisiae, the native ZIM2180 strain and commercial Fermol Premier Cru (FPC). RESULTS: In co-inoculation fermentations, non-Saccharomyces yeasts decreased colour intensity (on average by 25.5%). In wines fermented with ZIM624, the concentration of vinylphenolic pyranoanthocyanins increased (average concentration 1.5 mg L-1 ). However, vitisin concentration was significantly higher in S138 + FPC fermentation (1.3 mg L-1 and an average of 0.9 mg L-1 , respectively). Pinot Noir wines fermented with only ZIM2180 and sequential inoculation of ZIM624 + ZIM2180 resulted in significantly higher colour intensity (6.1 ± 0.0 AU and 4.4 ± 0.0 AU, respectively) and lower wine hue parameters compared to other wines. Sensory evaluation also showed that both wines had the highest perceived colour intensity and purple colour suggesting improvement in wine quality parameters. CONCLUSIONS: The results confirmed that selected indigenous starters made out of Saccharomyces and non-Saccharomyces yeasts can alter Pinot Noir wine colour parameters and improve wine colour properties. Those yeasts properties should be investigated prior to the development of new commercial starters but also be considered in large scale spontaneous fermentations of low colour intensity red wines like Pinot Noir. © 2021 Society of Chemical Industry.


Assuntos
Vitis/microbiologia , Vinho/análise , Leveduras/metabolismo , Cor , Fermentação , Microbiologia de Alimentos , Vitis/metabolismo , Vinho/microbiologia , Leveduras/classificação
5.
J Sci Food Agric ; 102(2): 724-731, 2022 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-34171125

RESUMO

BACKGROUND: Toasted vine shoots have recently been proposed as enological additives with the aim of improving the sensorial profile of wines. However, so far, there is no simple method for classifying vine shoots for this innovative enological practice. In this study, therefore, an enological aptitude classification for toasted vine shoots has been proposed for the first time. Moreover, given the need for quick techniques to be used in wineries to determine the main phenolic compounds of vine shoots, near-infrared (NIR) spectroscopy has been calibrated and validated. RESULTS: By means of a detailed statistical analysis, an enological classification of toasted vine shoots has been proposed based on their total polyphenol index and (+)-catechin, (-)-epicatechin, ellagic acid, and trans-resveratrol. Moreover, the NIR methodology that was developed showed good validation statistics and acceptable accuracy. CONCLUSIONS: This work proposes the first enological toasted vine-shoot classification and it provides a tool for rapid screening, mainly of phenolic compounds, in toasted vine shoots. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Assuntos
Extratos Vegetais/análise , Brotos de Planta/química , Vitis/química , Vinho/análise , Manipulação de Alimentos , Fenóis/análise
6.
Food Chem ; 371: 131157, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-34583180

RESUMO

Ochratoxin A (OTA) is a very important mycotoxin. However, there are few studies on the removal of OTA in wine because of the great influence on product quality and difficulty in practical application. A nano-MgO-modified diatomite ceramic membrane (MCM) with a high positive charge was prepared and applied to remove OTA in wine. The isotherm adsorption between the positively charged membrane and OTA was in accordance with the Langmuir model, with a maximum adsorption capacity of 806 ng/g at 25 °C. All of the changes in adsorption enthalpy (ΔH), adsorption free energy (ΔG) and adsorption entropy (ΔS) were negative, which indicated that the combination of nano-MgO MCM and OTA was a spontaneous exothermic and nonspecific physical adsorption process. The concentrations of OTA in adsorption-treated wines were lower than 2 µg/kg, and the removal rates exceeded 92%. After OTA removal, the composition of wines was preserved to some extent.


Assuntos
Ocratoxinas , Vinho , Adsorção , Cerâmica , Ocratoxinas/análise , Eletricidade Estática , Vinho/análise
7.
Food Chem ; 371: 131163, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-34583184

RESUMO

Wine final color, taste and aroma are closely related to the accumulation of secondary metabolites that may be affected by deficit irrigation applied in viticulture. A two-year study was conducted to assess the different fractions of crop evapotranspiration (ETc) irrigation replacement on wine composition, addressing the analysis of flavonoids and volatiles under context of global warming. Irrigating with 100% ETc (full grapevine demand) enhanced wine hue, antioxidant capacity, and some aromas; however, it came with a diminution of flavonoids and a less stable flavonoid profile. Replacing 25 and 50% ETc in wine grape improved wine color intensity, concentration of flavonoids, and shifted the aromatic profiles. These treatments increased some terpenes and esters which may enhance the desirable aromas for Cabernet Sauvignon, and decreased C6 alcohols related to unpleasant ones. Therefore, despite the warming trends in Mediterranean climates, 100% ETc irrigation would be not advisable to improve or maintain wine quality, and 50% ETc was sufficient.


Assuntos
Vitis , Vinho , Antocianinas/análise , Frutas/química , Fenóis/análise , Vinho/análise
8.
Food Chem ; 371: 131178, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-34583186

RESUMO

New microplasma source optical emission spectrometry (OES) for the determination of Na, K, Mg, Ca, and Zn in wine was developed. As the microplasma source, a solution anode glow discharge (SAGD) or a solution cathode glow discharge (SCGD) were employed. The diluted samples solutions (0.5-2%) were directly analyzed (no acid digestion required) and the detection limits of Na, K, Mg, Ca, and Zn were 0.015, 0.03, 3, 12, and 0.1 µg L-1, respectively. The developed method was used for the analysis of wine samples from the province of Lower Silesia (Poland). It was found that 1) red wines were characterized by a higher content of K and Mg, 2) it was possible to discriminate between Regent and Pinot Noir grape varieties (both red) by the concentrations of K and Ca, 3) the concentration of Na in the analyzed wines was lower than that found in wines from other European countries.


Assuntos
Vitis , Vinho , Europa (Continente) , Polônia , Análise Espectral , Vinho/análise
9.
Food Chem ; 371: 131168, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-34601211

RESUMO

This research aims at predicting sensory properties generated by the phenolic fraction (PF) of grapes from chemical composition. Thirty-one grape extracts of different grape lots were obtained by maceration of grapes in hydroalcoholic solution; afterward they were submitted to solid phase extraction. The recovered PFs were reconstituted in a wine model. Subsequently the wine models, containing the PFs, were sensory (taste, mouthfeel) and chemically characterized. Significant sensory differences among the 31 PFs were identified. Sensory variables were predicted from chemical parameters by PLS-regression. Tannin activity and concentration along with mean degree of polymerization were found to be good predictors of dryness, while the concentration of large polymeric pigments seems to be involved in the "sticky" percept and flavonols in the "bitter" taste. Four fully validated PLS-models predicting sensory properties from chemical variables were obtained. Two out of the three sensory dimensions could be satisfactorily modeled. These results increase knowledge about grape properties and proposes the measurement of chemical variables to infer grape quality.


Assuntos
Vitis , Vinho , Taninos/análise , Paladar , Percepção Gustatória , Vinho/análise
10.
Food Chem ; 372: 131158, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34601421

RESUMO

In this study, three modified glassy carbon electrodes based on three-dimensional conducting polymer nanocomposites (TDCPNs) were fabricated for evaluating the aging process of Huangjiu (Chinese rice wines). The electrochemical activity and experimental conditions of the TDCPNs modified electrodes were investigated by cyclic voltammetry, the aging information obtained by the modified electrodes were optimized by variance inflation factor (VIF). Principal components analysis (PCA), locally linear embedding (LLE), and locality preserving projection (LPP, which presented the best classification result) based on the optimized data were applied to classify the wine samples. Then, the dimensionality reduction data of PCA, LLE, and LPP were used as input variables of the logistic regression and extreme learning machine (ELM) for evaluating the aging process of Huangjiu, and the LLE-ELM method exhibited the best prediction results. These results demonstrated that the TDCPNs modified electrodes presented the potential for the quality analysis of food and beverages.


Assuntos
Nanocompostos , Vinho , China , Técnicas Eletroquímicas , Eletrodos , Análise de Componente Principal , Vinho/análise
11.
Food Chem ; 372: 131234, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34619522

RESUMO

Astringency is a dry puckering mouthfeel mainly generated by the binding of tannins with proteins in the mouth. Tannins confer benefits such as resistance to biotic stresses and have antioxidant activity, and moderate concentrations of tannins can improve the flavor of fruits or their products. However, fruits with high contents of tannins have excessive astringency, which is undesirable. Thus, the balance of astringency formation and removal is extremely important for human consumption of fruit and fruit-based products. In recent years, the understanding of fruit astringency has moved beyond the biochemical aspects to focus on the genetic characterization of key structural genes and their transcriptional regulators that cause astringency. This article provides an overview of astringency formation and evaluation. We summarize the methods of astringency regulation and strategies and mechanisms for astringency removal, and discuss perspectives for future exploration and modulation of astringency for fruit quality improvement.


Assuntos
Frutas , Vinho , Adstringentes , Frutas/química , Frutas/genética , Humanos , Taninos/análise , Paladar
12.
Food Chem ; 372: 131229, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34624784

RESUMO

Addition of oenological tannins claims to have a positive impact on wine stability, protection from oxidation and likely sensory persistence. However, their role on red wine aroma during oxidation is controversial. The present study aims at investigating the effect of addition of oenological tannins on wine flavour (mainly aroma) before and after air exposure. Temporal Dominance of Sensations, a dynamic sensory evaluation, was coupled with a dynamic chemical measurement (nosespace analysis) using a Proton-Transfer-Reaction Mass-Spectrometer connected to the nasal cavity of 17 assessors. Results showed that the oxidation of a non-oaked Pinot Noir red wine decreases the fruity aroma dominance and increases the maderised and prune one. A contextual decrease of the fruity ethyl decanoate and increase of oxidative Strecker aldehydes are observed. Ellagitannins but not proanthocyanidins preserved perception of fruitiness and prevented increase of maderised notes. Moreover, ellagitannins increase the aroma persistence mainly in the non-oxidized wine.


Assuntos
Odorantes , Vinho , Odorantes/análise , Percepção , Taninos , Paladar , Vinho/análise
13.
Food Chem ; 372: 131251, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34624786

RESUMO

Anthocyanin accounts for wine color performance, while it is susceptive to saccharomyces cerevisiae, causing threatened stability. Considering pyranoanthocyanin performed better color and stability, converting anthocyanins to pyranoanthocyanins in advance during fermentation was an ideal way for color improvement. Thus, pyruvic acid (PA) as the precursor of vitisin A was applied to fermentation with cyanidin-3-O-glucoside (C3G). Results showed that PA-stress leads to a color loss associated with a decrease in C3G and cyanidin. However, the content of pyranoanthocyanins under PA stress is unvaried. LC-MS-based non-target metabolomics revealed that superfluous PA can disturb the process of glycolysis and tricarboxylic acid cycle. Importantly, 1291 molecular features were increased and 1122 were decreased under PA-stress, in which several anthocyanins derivatization and isomerization were changed, contributing to color performance. This study indicated that extra PA is unfriendly to anthocyanins during fermentation, playing an adverse effect on color, which should be avoided in wine production.


Assuntos
Antocianinas , Vinho , Antocianinas/análise , Cor , Fermentação , Ácido Pirúvico , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Vinho/análise
14.
Food Chem ; 372: 131259, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34627087

RESUMO

A robust data fusion strategy integrating Tri-step infrared spectroscopy (IR) with electronic nose (E-nose) was established for rapid qualitative authentication and quantitative evaluation of red wines using Cabernet Sauvignon as an example. The chemical fingerprints of four types of wines were thoroughly interpreted by Tri-step IR, and the defined spectral fingerprint region of alcohol and sugar was 1200-950 cm-1. The wine types were authenticated by IR-based principal component analysis (PCA). Furthermore, ten quantitative models by partial least squares (PLS) were built to evaluate alcohol and total sugar contents. In particular, the model based on the fusion datasets of spectral fingerprint region and E-nose was superior to the others, in which RMSEP reduced by 47.95% (alcohol) and 79.90% (total sugar), rp increased by 11.95% and 43.47%, and RPD >3.0. The developed methodology would be applicable for mass screening and rapid multi-chemical-component quantification of wines in a more comprehensive and efficient manner.


Assuntos
Vinho , Bebidas Alcoólicas , Análise dos Mínimos Quadrados , Análise de Componente Principal , Espectrofotometria Infravermelho , Vinho/análise
15.
Talanta ; 236: 122857, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34635241

RESUMO

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.


Assuntos
Proantocianidinas , Vinho , Antocianinas/análise , Fenóis/análise , Espectrometria de Fluorescência , Vinho/análise
16.
Talanta ; 236: 122889, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34635268

RESUMO

Phenolic compounds are an interesting class of natural products because of their proposed contribution to health benefits of foods and beverages and as a bio-source of organic (aromatic) building blocks. Phenolic extracts from natural products are often highly complex and contain compounds covering a broad range in molecular properties. While many 1D-LC and mass spectrometric approaches have been proposed for the analysis of phenolics, this complexity inevitably leads to challenging identification and purification. New insights into the composition of phenolic extracts can be obtained through online comprehensive two-dimensional liquid chromatography (LC × LC) coupled to photodiode array and mass spectrometric detection. However, several practical hurdles must be overcome to achieve high peak capacities and to obtain robust methods with this technique. In many LC × LC configurations, refocusing of analytes at the head of the 2D column is hindered by the high eluotropic strength of the solvent transferred from the 1D to the 2D, leading to peak breakthrough or broadening. LC × LC combinations whereby a purely aqueous mobile phase is used in the 1D and RPLC is used in the 2D are unaffected by these phenomena, leading to more robust methods. In this contribution, the combination of temperature-responsive liquid chromatography (TRLC) with RPLC is used for the first time for the analysis of phenolic extracts of natural origin to illustrate the potential of this alternative combination for natural product analyses. The possibilities of the combination are investigated through analysis of wine extracts by TRLC × RPLC-DAD and TRLC × RPLC-ESI-MS.


Assuntos
Cromatografia de Fase Reversa , Vinho , Cromatografia Líquida , Fenóis/análise , Temperatura
17.
Food Chem ; 372: 131222, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34638059

RESUMO

Varietal thiols are important wine aroma compounds that are generally less abundant in red wines. Accentuated cut edges (ACE), known for accelerating phenolic extraction, was applied to Shiraz winemaking and compared with conventional crushing (NOACE) to examine the effects on varietal thiol precursor extraction and thiol formation. Water addition to grape must and skin contact time (SCT) during fermentation were also assessed. Although there was no difference for precursors in the must, ACE significantly decreased 3-S-glutathionylhexan-1-ol concentration during fermentation. 3-Sulfanylhexan-1-ol and ethyl esters were significantly influenced by crushing method and/or SCT, with NOACE or shorter SCT yielding higher concentrations. Acetates, higher alcohols, fatty acids, and isoprenoids differed according to the interaction of crushing method and SCT, with ACE and shorter SCT significantly enhancing all groups except acetates. Volatiles in Sauvignon blanc and Pinot noir wines produced at commercial scale with ACE were briefly evaluated, suggesting an impact of grape variety.


Assuntos
Vitis , Vinho , Acetatos/análise , Fermentação , Odorantes/análise , Fenóis/análise , Vinho/análise
18.
Food Chem ; 372: 131282, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34638064

RESUMO

With the objective of improving both the extraction of phenolic compounds from grapes and their maintenance in the final wine, we compared the effect of favoring phenolic extraction with a pectolytic-based maceration enzyme with that of favoring both phenolic extraction and the partial elimination of the suspended material using a pectolytic-based clarification enzyme. The phenolic composition of the final wines and those adsorbed to the precipitated lees were analyzed. Both enzymes increased wine color intensity and phenolic content, but the best results were observed when the clarification enzyme was used. This enzyme generated the largest losses of phenolics bound to precipitated lees. However, this resulted in a positive effect, the precipitation of lees rich in phenolic compounds probably created a pronounced gradient of phenolic compounds from grapes to must/wine and better chromatic characteristics in the final wine, compared with the wine made using a traditional maceration enzyme.


Assuntos
Vitis , Vinho , Antocianinas/análise , Cor , Fenóis/análise , Poligalacturonase , Vinho/análise
19.
Food Chem ; 372: 131288, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34655830

RESUMO

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.


Assuntos
Aminas Biogênicas , Vinho , Bebidas Alcoólicas/análise , Cerveja/análise , Aminas Biogênicas/análise , Cromatografia Líquida de Alta Pressão , Controle de Qualidade , Vinho/análise
20.
Food Chem ; 372: 131281, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34655832

RESUMO

The mechanism responsible for the appearance of the light-struck fault upon exposure of white wines and Champagnes to natural or artificial light is examined in light of new experiments involving methionine analogues. The latter show that the formation of volatile sulfur species upon irradiation of riboflavin in the presence of methionine in model wine solutions at pH 3 is not dependent on the existence of neighboring group stabilization of the sulfur-centered cation radical through a 5- or 6-membered cyclic intermediate. Instead, the formation of a dimer radical cation is proposed in agreement with the formation of oxidation products such as dimethyl disulfide at early reaction times and the observed steric effect upon product distribution. The limiting quantum yield for the release of sulfur atoms from a solution of methionine in model wine solutions at pH 3.5 containing riboflavin was found to be 0.26 (435 nm irradiation). No dependence of the quantum yield or product distribution on the irradiation wavelength was found over the range 365-90 nm.


Assuntos
Vinho , Aromatizantes , Metionina , Oxirredução , Paladar , Vinho/análise
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