Background and goals Every year, some white wine is lost during distribution because it has unexpectedly started to show oxidized character. One reason some wines taste "reduced" is that the winemaker has added excessive SO2 to avoid over-oxidation. While SO2 and ascorbate (where it is used) are the key preservatives in wine, some assays (FRAP, DPPH, and FolinCiocalteu method) used to predict a wine's protection from oxygen include a response to components such as phenolics. However, phenolics are not antioxidants; they function more like catalysts that are continually recycled by SO2, at least in white wine before over-oxidation. This research aimed to develop a rapid shelf-life test for white wine by predicting SO2 exhaustion during aging. Methods and key findings Commercial white wines (n = 8) experienced accelerated aging (air saturated and heated at 45 degrees C) and the total SO2 to O2 reaction ratio was calculated. Additionally, the SO2 addition method was used to determine the sulfite buffering factor of each sample. From those values, we derived a new formula, "potential wine shelf-life", that factors in O2 uptake through wine closures and initial and minimum SO2 levels to predict when a particular wine would exhaust its free SO2. Conclusions and significance "Potential wine shelf-life" can forecast when free SO2 levels drop below a necessary minimum, and the wine will start to exhibit oxidized character. The simple formula should provide winemakers with a much more precise estimate of the shelf-life of their white wines.

Astringency in red wine is primarily caused by condensed tannins interaction with salivary proteins, thus contributing to wine mouthfeel. Condensed tannin cleaves in the presence of acid, and the reactive electrophilic intermediates react largely with tannin, the most abundant nucleophiles, re-forming tannin, but may react with others. Here we hypothesize that glutathione (GSH) interacts with the C4-carbocations formed during acid-catalyzed depolymerization of tannins in red wine, forming glutathionyl-flavan-3-ol adducts. Using targeted LC-QToF-MS analysis, glutathionyl-flavan-3-ol adducts at the tannin linkage are reported in wine for the first time. Studying 24 Washington red wines aged between 1 and 20 years of age, the highest amounts for these adducts were observed in 1-year-old wines followed by losses as wines aged. The impact of glutathione supplementation on adduct formation was tested in experimental Cabernet Sauvignon wines, showing a five-fold increase in adduct concentration compared to controls after one year of bottle ageing. Additionally, a reduction in protein-precipitable tannins was observed for model solution and supplemented wines, suggesting that glutathionyl-flavan-3-ol adducts might contribute to reduced astringency perception in aged wine. Future studies are needed to confirm the stability of these adducts and explore their sensory effects on wine mouthfeel.

During wine ageing, tannins could react with sulfur dioxide to form sulfonated flavanols which are anticipated to alter tannin binding to proteins contributing to the reduction of astringency during ageing. Previous studies have identified or quantified monomeric and dimeric sulfonated flavanols in aged wines, but the evolution of sulfonated tannins has been lacking. Here, we quantified sulfonated tannins in three Washington state vineyards over a 20-year period, employing targeted LC-QToF analysis. Analysis of 24 wines revealed a systematic trajectory of sulfonated tannins over 20 years. Sulfonated monomers rose consistently with wine age, becoming the dominant form of sulfonated products in all samples at the 20-year mark. Concurrently, there was a decline in native tannins and sulfonated oligomers, suggesting a process of acid-catalyzed depolymerization of native tannins followed by sulfonation via reaction with sulfur dioxide. Future work is needed to understand the stability of sulfonated tannins and their impact on wine astringency.

Journal of the Science of Food and AgricultureVolume 104, Issue 1 p. 9-9 Editorial A home for multidisciplinary project reports Andrew L. Waterhouse, Andrew L. Waterhouse University of California, Davis, CA, USASearch for more papers by this authorSandra Schmöckel, Sandra Schmöckel University of Hohenheim, Stuttgart, GermanySearch for more papers by this author Andrew L. Waterhouse, Andrew L. Waterhouse University of California, Davis, CA, USASearch for more papers by this authorSandra Schmöckel, Sandra Schmöckel University of Hohenheim, Stuttgart, GermanySearch for more papers by this author First published: 17 November 2023 https://doi.org/10.1002/jsfa.13063Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. REFERENCE 1Shepherd M and Waterhouse A, Sustainable food production requires interdisciplinary teams. J Sci Food Agric 102: 7 (2022). 10.1002/jsfa.11614 CASPubMedWeb of Science®Google Scholar Volume104, Issue115 January 2024Pages 9-9 ReferencesRelatedInformation

BACKGROUND:Historically, the effect of wine grape shading on flavonoids has investigated the impact of light incidence on proanthocyanidin (PA), flavonol, or anthocyanin concentration. In addition to concentration, the current experiment was designed to look at changes in PA composition, size and tannin activity through ripening. Tannin activity is a methodology for assessing the impact of structure and size on the affinity of tannin towards a hydrophobic surface and is considered to be a proxy for predicted astringency descriptive quality. In 2016 a shade cloth study was imposed on Cabernet Sauvignon on Mt Veeder, within the larger Napa Valley viticultural area. A control, which was unshaded, and two treatments consisting of 40% and 80% shade were applied at the onset of veraison.RESULTS:Results showed significant differences in the composition and concentration of anthocyanins throughout ripening. Compositional differences in PA were also observed, where shaded treatments had a significantly higher proportion of galloylated subunits. The molecular mass of the extracted tannin was significantly lower in the unshaded control than in the 80% shade treatment. These factors led to a lower measured tannin activity in extracts from exposed fruit.CONCLUSION:This work suggests that manipulation of canopy architecture, such as artificial shading, leads to changes in berry pigmentation, tannin composition and activity. These results show that the astringency and mouthfeel characteristics of a wine may be altered by vineyard management practices. © 2023 Society of Chemical Industry.

In 2015, an experiment was designed to investigate the distribution and variance of in winegrape flavonoids across the ripening phase in the Napa Valley. This Cabernet Sauvignon experiment was intended to evaluate the polyphenol differences across Napa Valley in order to understand parameters controlling "proanthocyanidin activity." This method has shown promise in understanding proanthocyanidin (PA) astringency based on size distribution, pigmentation, conformation, and composition. Results from whole berry partial extractions showed that seed PA material was driving PA activity early in the ripening phase, while the formation of the pigmented polymer led to a decrease later in the growing season. Multivariate analysis showed that the main drivers of changes across the ripening phase were the molecular masses of PAs and the amount of pigmentation. Given the high amount of variability seen in the experiment between sites in such a small geographical area, the results suggest that manipulation of PA activity may be possible in the vineyard, perhaps explaining variations in wine mouthfeel attributes between locations. These results can be used to develop furthermore controlled experiments targeting the variables responsible for PA activity changes.

The consumption of red wine induces headaches in some subjects who can drink other alcoholic beverages without suffering. The cause for this effect has been attributed to a number of components, often the high level of phenolics in red wine, but a mechanism has been elusive. Some alcohol consumers exhibit flushing and experience headaches, and this is attributed to a dysfunctional ALDH2 variant, the enzyme that metabolizes acetaldehyde, allowing it to accumulate. Red wine contains much higher levels of quercetin and its glycosides than white wine or other alcoholic beverages. We show that quercetin-3-glucuronide, a typical circulating quercetin metabolite, inhibits ALDH2 with an IC50 of 9.6 µM. Consumption of red wine has been reported to result in comparable levels in circulation. Thus, we propose that quercetin-3-glucoronide, derived from the various forms of quercetin in red wines inhibits ALDH2, resulting in elevated acetaldehyde levels, and the subsequent appearance of headaches in susceptible subjects. Human-subject testing is needed to test this hypothesis.

Abstract The creation of artisanal wine starts by creating a vineyard where the site is compatible with the specific grape varieties that are planted there. Once the vineyard is established, the cultivation techniques such as irrigation, pruning, and cover crops will affect the grape qualities. The harvest timing decision has a major impact on the resulting wine, and the subsequent winemaking decisions on crushing, pressing, yeast and barrel selection, as well as many other choices can result in a very particular, perhaps unique wine. A question is whether or not the wine is truly unique, and could an informed taster identify the artisan winemaker?

A Napa Valley Sauvignon blanc wine was bottled with 200 each of a natural cork, a screw cap, and a synthetic cork. As browning is an index for wine oxidation, we assessed the brown color of each bottle with a spectrophotometer over 30 months. A random-effects regression model for longitudinal data on all bottles and closure groups found a browning growth trajectory for each closure group. Changes in the wine’s browning behavior at 18 months and 30 months showed that the browning of the wine bottles appeared to slow down later in the storage period, especially for natural corks. The between-bottle variation was the highest for the natural cork. At 30 months, we separated the bottles by the extent of browning and samples were pulled from the high, mid, and low levels of browning levels for each closure. The degree of browning is inversely correlated with free SO2 levels ranging from 5 to 12 mg/L. However, a Quantitative Descriptive Analysis (QDA™) sensory panel could not detect any difference in their aroma and flavor profile between closure types regardless of browning level. Even low levels of free SO2 retain protection against strong oxidation aromas, and visual browning detected by spectrophotometer seemed to precede oxidative aroma and flavor changes of the aging Sauvignon blanc.

Journal of the Science of Food and AgricultureVolume 102, Issue 7 p. 2629-2629 Editorial SCI: 140 years documenting the application of chemistry-based science Peter Hambleton, Corresponding Author Peter Hambleton peterhambleton@btinternet.com Society of Chemical Industry, London, UK Correspondence to: Peter Hambleton, Society of Chemical Industry, 14/15 Belgrave Square, London, SW1X 8PS, UK. E-mail: peterhambleton@btinternet.comSearch for more papers by this authorAndrew Waterhouse, Andrew Waterhouse Editor-in-Chief JSFA University of California, Davis, CA, USASearch for more papers by this author Peter Hambleton, Corresponding Author Peter Hambleton peterhambleton@btinternet.com Society of Chemical Industry, London, UK Correspondence to: Peter Hambleton, Society of Chemical Industry, 14/15 Belgrave Square, London, SW1X 8PS, UK. E-mail: peterhambleton@btinternet.comSearch for more papers by this authorAndrew Waterhouse, Andrew Waterhouse Editor-in-Chief JSFA University of California, Davis, CA, USASearch for more papers by this author First published: 15 April 2022 https://doi.org/10.1002/jsfa.11855Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume102, Issue7May 2022Pages 2629-2629 RelatedInformation

Quinone formation is a key initial step of wine oxidation. Nucleophiles sacrificially react with quinones to sustain color and aroma, but due to the complexity of wine, determining the identity of the constitutive nucleophile has been challenging. Here we apply a novel stable-isotope labelling approach combined with high-resolution mass spectrometry, using C-13(6)-labelled ortho-quinone. This allows for the specific detection of quinone reaction products with M and M + 6x peak feature-pairs in real wines. Analysis using MetExtract II successfully identified 225 quinone reaction suspects in negative mode in Sauvignon blanc wine, and 120 in Cabernet Sauvignon. Ten quinone reaction products with the most abundant peak areas were tentatively identified using a mass/structure workflow. It appears that sulfides largely quench quinones in white wines, whereas flavonoids are the dominant reactants in red wines. The latter result demonstrates how skin/seed extraction preserves red wine.

At a key branchpoint in wine oxidation, hydrogen peroxide reacts either with iron(II), leading to the Fenton oxidation of ethanol, or with sulfur dioxide, precluding oxidation. The fate of H2O2 was investigated in anoxic model wines with different pH and acid buffers. In the absence of SO2, anoxic conditions allowed the stoichiometric production of acetaldehyde from H2O2 despite iron(II) being limiting, indicating efficient iron redox cycling. Acetaldehyde production was faster at pH 4.0 than at pH 3.0, attributable largely to increased iron complexation. Citrate allowed the most rapid acetaldehyde formation, while the comparative effects of tartrate and malate were pH-dependent, likely due to differences in their iron-chelating abilities. The inclusion of SO2 greatly diminished acetaldehyde formation, but did not prevent it, and reduced the differential effects of pH and acid composition. Findings overall suggest management of wine acidity can significantly affect the rate and outcome of oxidation.

Background and Aims This study examines the effect of microoxygenation (MOX) applied before and after malolactic fermentation (MLF) on monomeric phenolic compounds and the tannin composition of a young Pinot Noir wine. It provides a complementary study to an earlier report on the effect of MOX on Pinot Noir colour and pigment development. Methods and Results Two oxygen doses [10.8 and 52.4 mg O-2/(L center dot month)] were applied either before or after MLF for 30 days. The wines were analysed by a series of HPLC-based methods for phenolic compounds, with sources including both the Pinot Noir grape and a minor contribution from commercial tannin and oak additives. Post-MLF MOX led to the near complete hydrolysis of cis- and trans-coutaric acids and to the conversion of trans-caftaric acid to caffeic acid, which has been associated with MLF. An increase of syringic acid was also found with post-MLF MOX. For tannin composition, MOX decreased the proportion of trihydroxylation (%Tri-OH) but increased galloylation (%Galloyl). Between MOX treatments, the effect of MOX dosage was much stronger than MOX timing on phenolic measures. Conclusions Post-MLF MOX greatly affected the enzymatic hydrolysis of hydroxycinnamic acids. With MOX, the decrease in %Tri-OH and the increase in %Galloyl could increase astringency perception. The higher oxygen dosage had a greater impact on tannin composition than shown previously with colour-related parameters. Significance of the Study The influence of MOX on Pinot Noir phenolic composition has not been reported previously in such detail. Applying MOX to a young Pinot Noir wine altered the phenolic units responsible for astringency.

Background and Aims Microoxygenation (MOX) is widely used in winemaking. Its impact, however, on Pinot Noir wines has not been well documented. We investigated the influence of MOX on colour parameters and on the anthocyanin and polymeric pigment concentration of a young Pinot Noir wine. The relationship between MOX, yeast growth and acetaldehyde production was also explored. Methods and Results Microoxygenation was applied before or after malolactic fermentation (MLF), and at two oxygen doses [10.8 and 52.4 mg/(L center dot month)], for 30 days. The end result was reported after dissolved oxygen was depleted and 90 mg/L SO2 was added. Microoxygenation induced a higher yeast growth and acetaldehyde production, where the latter was associated with both yeast metabolism and chemical oxidation. A larger loss in total anthocyanins and malvidin-3-glucoside occurred under MOX but absorbance at 520 nm and colour intensity were higher. With the higher oxygen dose, MOX promoted the formation of large polymeric pigments. Conclusions Acetaldehyde formation was strongly induced by MOX, contributing to reactions between anthocyanins and acetaldehyde forming pigments in the red spectrum. Between MOX treatments, only slight variation was found for each parameter, indicating a less important effect of the timing and dosage of MOX on the young Pinot Noir wine than anticipated from prior work. Significance of the Study Microoxygenation caused a significant impact on the colour development of light-coloured Pinot Noir wine, increasing the colour intensity.

Andrew Waterhouse: Both JSFA as well as JSFA Reports cover a wide range of topics in food, agriculture and related interdisciplinary fields. While JSFA has a strict aims and scope with novelty being a very important aspect, JSFA Reports will encourage publication of manuscripts that do not meet the criteria when it comes to cutting edge novelty. This will include regional studies, process optimisations, replication studies and survey studies with a limited hypothesis. We are also including some topics that are currently outside the scope of JSFA, but closely related and of interest to the readers of JSFA. MS: When an author submits a paper to JSFA, the manuscript is considered for publication in JSFA Reports too. Papers that fall outside the aims and scope of JSFA will be transferred to JSFA Reports whenever appropriate. Authors also have the option to opt out of this transfer service. JSFA Reports is here to save authors and reviewers time and effort by building in a seamless second option. AW: Cascade journals as we call them are not a new concept. Several prominent journals like Nature Journals, BMJ, Lancet, JAMA and Cell have such transfer facilities. Wiley has its own referral service called Manuscript Transfer to provide authors options amongst the Wiley journals. Now that JSFA's cascade journal, JSFA Reports is being launched, we look forward to helping many more authors find a good home for their papers.

As Editors of JSFA, we are pleased to announce a new initiative on behalf of The Society of Chemical Industry (SCI: JSFAʼs owning society) and our publishers Wiley. JSFAʼs popularity means that we receive many more submissions than we can publish. As a result, our rejection rate is high, and this means that many of the manuscripts that we turn away contain sound science and deserve to be published - and are indeed eventually published in other journals. We are therefore launching JSFA Reports, to provide a good home for these papers. We want to improve the journalʼs service to authors, by offering an option that will be a significant time (and effort) saver for researchers and editors, allowing the authors to avoid the work of starting afresh with a new journal. We will be leading both journals as Editors-in-Chief. JSFA Reports will be managed by Dr. Anna Kynadi as the Deputy Editor-in-Chief. We see JSFA Reports as providing a home for those papers that are solid research but fall just slightly outside the aims and scope of JSFA, for instance regional studies, process optimisations, replication studies and survey studies with a limited hypothesis. There also likely to be topics currently outside of our scope that could be encompassed. However, we stress these studies would still need to be to an excellent standard, possessing solid data and good analysis of that data, but might not have the broad application or international readership that we seek for JSFA papers. Such publications might be of great value to researchers or industrialists who are trying to apply the research data as a base for further research or for commercial benefits. While replication studies provide validation and generalizability for protocols/experimental set ups etc., regional studies and process optimisations might help reduce the R&D expenses when moving from laboratory scale to industry. The concept of such a journal, sometimes called a cascade journal, is not new. It is employed in a number of places, perhaps best known is among the Nature journals, but BMJ, Lancet, JAMA, and Cell and many others employ the same approach. In a similar effort, you might have seen that Wiley has just initiated a referral service amongst some of its journals called Manuscript Transfer (wiley.com), that provides authors with a similar option between any of the participating Wiley journals. We are not under any illusion that JSFA is rejecting papers of the same caliber as Nature, but the high rejection rate means that we do turn down much publishable material. The idea of JSFA Reports is to save authors and reviewers time and effort by building in a seamless second option. JSFA Reports is set to launch in this summer, and once operational, authors submitting to JSFA would have their submissions considered for both journals. Papers that are scientifically sound but not suitable for JSFA would be transferred to JSFA Reports and be considered there with the authorʼs permission. We look forward to helping many more authors find a good home for their papers in short order.

Condensed tannin extraction and stable color formation are two of the cornerstones of red wine production. Without condensed tannin, red wine would lack the tactile feeling of astringency, and without the formation of modified pigments, it would lack color stability for long-term aging. To understand how malvidin-3,5-diglucoside interacts with condensed tannin under nonoxidative conditions, an experiment was designed conducting model-wine skin extractions of Sauvignon blanc grapes harvested at various dates of maturity. Monomeric malvidin-3,5-diglucoside was isolated from color concentrate and added during these extractions. Following a 72 h extraction, solutions were evaluated for recovery of monomeric anthocyanins, skin tannin concentration, skin tannin extractability, and impact of anthocyanins on condensed tannin size. Anthocyanins showed a significant impact on the extraction of flavan-3-ol material in the early stages of ripening that declined in the latter stages of ripening. Furthermore, anthocyanins significantly decreased the size of the condensed tannin extracted. These results suggest that anthocyanins are not only enhancing the extractability of condensed tannin but also readily incorporating into the polymeric material, leading to a decrease in the average molecular mass of the condensed tannin polymer. The extent of reaction in 72 h suggests that the rate of interflavan bond cleavage may be higher than previously reported and merits closer scrutiny.