Micro-oxygenation is a process used in winemaking to introduce

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

into

wine Wine is an alcoholic drink made from Fermentation in winemaking, fermented fruit. Yeast in winemaking, Yeast consumes the sugar in the fruit and converts it to ethanol and carbon dioxide, releasing heat in the process. Wine is most often made f ...

in a controlled manner. Developed in 1991 by Patrick DuCournau, working with the exceptionally tannic grape Tannat in Madiran, the process gained usage in modern winemaking following the 1996 authorization by the

European Commission The European Commission (EC) is the primary Executive (government), executive arm of the European Union (EU). It operates as a cabinet government, with a number of European Commissioner, members of the Commission (directorial system, informall ...

. Today, the technique is widely employed in

Bordeaux Bordeaux ( ; ; Gascon language, Gascon ; ) is a city on the river Garonne in the Gironde Departments of France, department, southwestern France. A port city, it is the capital of the Nouvelle-Aquitaine region, as well as the Prefectures in F ...

, as well as at least 11 different countries, including the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

and

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

. J. Robinson (ed) ''"The Oxford Companion to Wine"'' Third Edition pg 442-443 Oxford University Press 2006

Process

The process of micro-oxygenation involves a large two-chamber device with valves interconnected to a tank of oxygen. In the first chamber, the oxygen is calibrated to match the

volume Volume is a measure of regions in three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch) ...

of the wine. In the second chamber, the oxygen is injected into the wine through a porous

ceramic A ceramic is any of the various hard, brittle, heat-resistant, and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcela ...

stone located at the bottom of the chamber. The dosage is controlled and can range anywhere from .75 to 3 cubic centimetres per liter of wine. The process normally occurs in multiple treatments that can last anywhere from one or two treatments during the early stages of

fermentation Fermentation is a type of anaerobic metabolism which harnesses the redox potential of the reactants to make adenosine triphosphate (ATP) and organic end products. Organic molecules, such as glucose or other sugars, are catabolized and reduce ...

(to help avoid stuck fermentation) to a more prolonged treatment during the maturation period that can last four to eight months. Micro-oxygenation affects

colour Color (or colour in Commonwealth English; see spelling differences) is the visual perception based on the electromagnetic spectrum. Though color is not an inherent property of matter, color perception is related to an object's light absorp ...

, aromatic bouquet, mouth-feelSensory characteristics changes of red Grenache wines submitted to different oxygen exposures pre and post bottling. Soline Caillé, Alain Samson, Jérémie Wirth, Jean-Baptiste Diéval, Stéphane Vidal and Véronique Cheynier, Analytica Chimica Acta, 15 February 2010, Volume 660, Issues 1–2, Pages 35–42, and phenolic content.The impact of oxygen exposure before and after bottling on the polyphenolic composition of red wines. J. Wirth, C. Morel-Salmi, J.M. Souquet, J.B. Dieval, O. Aagaard, S. Vidal, H. Fulcrand and V. Cheynier, Food Chemistry, 1 November 2010, Volume 123, Issue 1, pages 107–116, Carboxypyranoanthocyanidins can be considered markers of microoxygenation techniques.

Benefits

Exposure to oxygen during production may improve wine, but the exposure must be limited: too much oxygen can lead to

oxidation Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...

while too little can lead to reduction, either one leading to its associated wine faults. In barrel aging, the natural properties of the wood allow for gentle aeration of the wine to occur over a prolonged period. This aids in

polymerization In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many fo ...

tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and Precipitation (chemistry), precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' is widel ...

into larger molecules, which could fall out of solution, not promoting protein precipitation in the mouth and thus improving mouth astringency. The process of micro-oxygenation aims to mimic the effects of slow barrel maturation in a shorter period or for lower cost. It also enables more control over the process. During fermentation, the added oxygen can help maintain the viability of the

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom (biology), kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are est ...

to minimize the risk of stuck fermentation and the production of undesirable sulfides. After fermentation it can aid in the clarification and stabilization of the wine without resorting to the use of fining agents.

References

{{reflist Winemaking Wine terminology