IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 Controlling Wine Oxidation: Effects of pH on Key Reaction Rates

Controlling Wine Oxidation: Effects of pH on Key Reaction Rates

Abstract

Acidity is often touted as a predictor of wine ageability, though surprisingly few studies have systematically investigated the chemical basis for this claim. The effects of pH on the rates of several key reactions in the wine oxidation pathway were evaluated in model wine. Wine oxidation starts with the redox cycling of iron between two oxidation states: iron(II) is oxidized by oxygen while iron(III) is reduced by phenols. While iron(III) reduction slowed as pH was increased from 3 to 4, oxygen consumption by iron(II) accelerated. However, pseudo-first order rate constants for oxygen consumption remained at least ten times lower than those of iron(III) reduction, suggesting that iron(II) oxidation is the rate-determining reaction for wine oxidation, and wine aging is thus limited by oxygen ingress. Despite this, different wines subject to the same oxidative conditions will often vary in their rate of maturation, indicating another control point “downstream” in the oxidation pathway. Hydrogen peroxide formed upon the reduction of oxygen can react in one of two ways: the iron-catalyzed Fenton oxidation of ethanol into acetaldehyde, or quenching by sulfur dioxide. Acetaldehyde production from added H2O2 was faster at pH 4 than at pH 3, while the efficacy of SO2 as an antioxidant was diminished, lending credence to the notion that high-pH wines deteriorate more quickly than more acidic wines. These observations may be explained by the pH-dependent complexation of iron by tartrate and other carboxylic acids in wine, which determines the reduction potential of iron and controls its reactivity. Findings overall suggest viticultural and winemaking practices, as they pertain to the management of wine acidity, may have significant long-term repercussions on aging.

DOI:

Publication date: June 23, 2022

Issue: IVAS 2022

Type: Article

Authors

Nguyen Thi1

1Weincampus Neustadt, Institute for Viticulture and Oenology, Dienstleistungszentrum Ländlicher Raum (DLR), Breitenweg 71, 67435 Neustadt an der Weinstraße, Germany

Contact the author

Keywords

wine ageing, oxidation, iron, acidity, Fenton

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

Influence of climate change conditions (elevated CO2 and temperature) on the grape composition of five tempranillo (Vitis vinifera L.) Somatic variants

The current levels of greenhouse gas emissions are expecting to provoke a change on the environmental conditions which, among others, will include a rise of global mean surface temperature and an increment of atmospheric CO2 levels (IPCC, 2014), known as climate change. The response of grapevine (Vitis vinifera L.), one of the most important crops in Europe, from both a cultural and economic point of view, is not completely understood yet and the studies considering the interaction between factors are scarce. Besides, the potential variety of responses among somatic variants needs to be studied in order to be exploited in the avoidance of undesired traits linked to climate change (Carbonell‐Bejerano et al., 2015).

Read More

Winemaking techniques and wine tasting methods at the end of the Middle Ages

Les pratiques de vinification et de dégustation du vin sont souvent perçues, à travers un discours marketing très puissant, sous l’angle d’une tradition millénaire qui perdure depuis le Moyen Âge. En Bourgogne, il est courant de rattacher les racines de ces pratiques à l’activité des institutions ecclésiastiques qui possédaient d

Read More

Isolation of indigenous yeast strains from the Purcari and Trifești wine centers in the Republic of Moldova and evaluation of their impact on the quality of dry red wines

In the conducted research, 30 yeast strains from red grape varieties were isolated from the Purcari wine center, and 28 yeast strains from red grape varieties were isolated from the Trifești wine center in the Republic of Moldova.

Read More

Aroma compounds involved in the fruity notes of red wines potentially adapted to climate change.

Currently, climate change represents one of the major issues for the wine sector. The increasing temperature already recorded and expected in the upcoming years reduce the vegetative cycle of the grape varieties planted in Bordeaux area, affecting the physicochemical parameters of grapes and consequently, the quality of wine. From a sensory point of view, the attenuation of the fresh fruity character in some varietals is accompanied by the accentuation of dried-fruit notes [1]. As a new adaptive and ecological strategy on global warming, some winegrowers have initiated changes in the Bordeaux blend of vine varieties using late-ripening grape varieties [2]. 

Read More

The future of wine grape growing regions in europe

Recent warming trends in climatic patterns are now evident from observational studies. Nowadays, investigating the possible impacts of climate change on biological systems has a great importance in several fields of science.

Read More