Micro-oxygenation is a process used in

winemaking Winemaking or vinification is the production of wine, starting with the selection of the fruit, its fermentation into alcohol, and the bottling of the finished liquid. The history of wine-making stretches over millennia. The science of wine and ...

to introduce

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...

into

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

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 executive of the European Union (EU). It operates as a cabinet government, with 27 members of the Commission (informally known as "Commissioners") headed by a President. It includes an administrative body ...

. Today, the technique is widely employed in

Bordeaux Bordeaux ( , ; Gascon oc, Bordèu ; eu, Bordele; it, Bordò; es, Burdeos) is a port city on the river Garonne in the Gironde department, Southwestern France. It is the capital of the Nouvelle-Aquitaine region, as well as the prefectu ...

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

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

and

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...

. 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 occupied 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 Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...

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, porcelain, ...

stone located at the bottom of the chamber. The dosage is controlled and can range anywhere from .75 to 3 cubic centimetres per

liter The litre (international spelling) or liter (American English spelling) (SI symbols L and l, other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metre (m3) ...

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 metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food p ...

(to help avoid

stuck fermentation A stuck fermentation occurs in brewing beer or winemaking when the yeast become dormant before the fermentation has completed. Unlike an "arrested fermentation" where the winemaker intentionally stops fermentation (such as in the production of ...

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

colour Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are associ ...

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

while too little can lead to reduction, either one leading to its associated

wine faults A wine fault or defect is an unpleasant characteristic of a wine often resulting from poor winemaking practices or storage conditions, and leading to wine spoilage. Many of the compounds that cause wine faults are already naturally present in wine ...

. In

barrel aging A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, u ...

, the natural properties of the wood allow for gentle

aeration Aeration (also called aerification or aeriation) is the process by which air is circulated through, mixed with or dissolved in a liquid or other substances that act as a fluid (such as soil). Aeration processes create additional surface area in ...

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 f ...

tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner'' ...

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. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constit ...

to minimize the risk of

and the production of undesirable

sulfides Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds la ...

. 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