Macrowine 2021
IVES 9 IVES Conference Series 9 Quantification of the production of hydrogen peroxide H2O2 during wine oxidation

Quantification of the production of hydrogen peroxide H2O2 during wine oxidation

Abstract

Chemical studies aiming at assessing how a wine reacts towards oxidation usually focus on the characterization of wine constituents, such as polyphenols, or oxidation products. As an alternative, the key oxidation intermediate hydrogen peroxide H2O2 has never been quantified, although it plays a pivotal role in wine oxidation. H2O2 is obtained from molecular oxygen as the result of a first cascade of oxidation reactions involving metal ions and polyphenols. The produced H2O2 then reacts in a second cascade of oxidation to produce reactive hydroxyl radicals that can attack almost any chemical substrate in wine. Here, we show that based on an assay used in biotechnological analytics, the Amplex Red Assay, a fluorescence method can be developed to quantify H2O2 in wine. The non-fluorescent Amplex Red reagent was catalytically converted into a fluorescent product in presence of H2O2. Wine samples were left to react with oxygen during 30 min before read out. The fluorescence intensity provided quantification of the total integrated production of H2O2 during the measurement period. Within-day as well as between-day variabilities were small (CV < 1%, respectively 1.5%). H2O2 levels were very low in white wines compared to red wines demonstrating the importance of polyphenols. Moreover, H2O2 increased with temperature and the addition of metal ions. By contrast, H2O2 levels did not correlate with the concentration of many common wine constituents such as polyphenols or sulphur dioxide except for polymerized pigments, which played a major role. Furthermore, H2O2 levels were independent of the anti-oxidant properties of the wines. In general, this study demonstrates that the oxidation reactions in wines involve a complex interplay of chemical species that can only be grasped using a holistic approach. We speculate that this novel concept of quantifying the production of intermediates by trapping, using a fluorescent reporter, will open the path to detailed studies aiming at deciphering oxidation mechanisms in wines.

Publication date: May 17, 2024

Issue: Macrowine 2016

Type: Poster

Authors

Jean-Manuel Segura*, Benoit Bach, Julien Ducruet, Julien Héritier, Patrik Schönenberger, Vanessa Gaillard

*HES-SO

Contact the author

Tags

IVES Conference Series | Macrowine | Macrowine 2016

Citation

Related articles…

Impact of smoke exposure on the chemical composition of grapes

Vineyard exposure to smoke can lead to grapes and wine which exhibit objectionable smoky and ashy aromas and flavours, more commonly known as ‘smoke taint’ [1, 2]. In the last decade, significant bushfires have occurred around the world, including near wine regions in Australia, Canada, South Africa and the USA, as a consequence of the warmer, drier conditions associated with climate change. Considerable research has subsequently been undertaken to determine the chemical, sensory and physiological consequences of grapevine exposure to smoke. The sensory attributes associated with smoke-tainted wine have been linked to the presence of several smoke-derived volatile phenols, such as guaiacols, syringols and cresols [2].

Analysis of voltammetric fingerprints of different white grape musts reveals genotype-related oxidation patterns

Must oxidation is a complex process involving multiple enzymatic transformations, including the oxidation of phenolics containing an ortho-diphenol function. The latter process has a primary influence on wine aroma characteristics and stability, due to the central role of ortho-diphenols in the non-enzymatic oxidative reactions taking place during winemaking and in finished wine. Although oxidation of must is traditionally avoided, in recent years its contribution to wine quality has been revisited, and in some cases improvements to wine aroma have been observed with the application of controlled must oxidation. Nowadays there is a great interest in the wine industry towards the identification of specific markers or patterns to characterize and classify the response of grape must to oxidation.

Using combinations of recombinant pectinases to elucidate the deconstruction of the polysaccharide‐rich grape cell wall during winemaking

The effectiveness of enzyme-mediated maceration processes in red winemaking relies on a clear picture of the target (berry cell wall structure) to achieve the optimum combination of specific enzymes to be used. However, we lack the information on both essential factors of the reaction (i.e. specific activities in commercial enzyme preparation and the cell wall structure of berry tissue). In this study, the different combinations of pure recombinant enzymes and the recently validated high throughput cell wall profiling tools were applied to extend our knowledge on the grape berry cell wall polymeric deconstruction during the winemaking following a combinatorial enzyme treatment design.

Influence of wood chips addition during alcoholic fermentation on wine phenolic composition

This study investigates the effect of wood chips addition during the alcoholic fermentation on the phenolic
composition of the produced wines. A series of wood chips, originating from American, French, Slavonia
oak and Acacia were added at the beginning of wine alcoholic fermentation. Besides, a mixture consisting
of 50% French and 50% Americal oak chips were added during the experimentation. The wine samples
were analyzed one month after the end of malolactic fermentation, examining various chemical
parameters such as total anthocyanins, total phenolic content, tannins combined with protein (BSA) and
ellagitannin content.

How pressing techniques affect must composition and wine quality of Pinot blanc

This study investigates how the sensory profile of Pinot Blanc is affected from different maceration and pressing techniques. Grapes were sourced from four vineyards in the village Tramin in South Tyrol. For the experiment 200 kg of grapes from each vineyard site were hand picked the day before harvest for the commercial winery took place. Grapes were stored over night at 4°C, homogenized and processed in the experimental winery at Laimburg research centre the day after harvest. Four different pressing techniques were applied in duplicates of 100kg each.