Carbonic maceration is a
winemakingWinemaking, or vinification, is the production of wine, starting with selection of the grapes or other produce and ending with bottling the finished wine. Although most wine is made from grapes, it may also be made from other fruit or non-toxic plant material...
technique, often associated with the
French wineFrench wine is produced in several regions throughout France, in quantities between 50 and 60 million hectolitres per year . France has the world's largest wine production ahead of Italy and the second-largest total vineyard area behind Spain...
region of
BeaujolaisBeaujolais is a French Appellation d'Origine Contrôlée wine generally made of the Gamay grape which has a thin skin and few tannins. Like most AOC wines they are not labeled varietally. Whites from the region, which make up only 1% of its production, are made mostly with Chardonnay grapes though...
, in which whole grapes are
fermentedThe process of fermentation in wine is the catalyst function that turns grape juice into an alcoholic beverage. During fermentation yeast interact with sugars in the juice to create ethanol, commonly known as ethyl alcohol, and carbon dioxide...
in a
carbon dioxideCarbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state...
rich environment prior to crushing. Conventional
alcoholic fermentationEthanol fermentation is a biological process in which sugars such as glucose, fructose, and sucrose are converted into cellular energy and thereby produce ethanol and carbon dioxide as metabolic waste products....
involves crushing the grapes to free the juice and pulp from the skin with
yeastYeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with about 1,500 species currently described; they dominate fungal diversity in the oceans. Most reproduce asexually by budding, although a few do so by binary fission...
s serving as a the catalyst in converting
sugarSugar is a class of edible crystalline substances, mainly sucrose, lactose, and fructose. Human taste buds interpret its flavor as sweet. Sugar as a basic food carbohydrate primarily comes from sugar cane and from sugar beet, but also appears in fruit, honey, sorghum, sugar maple , and in many...
into
ethanolEthanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug, best known as the type of alcohol found in alcoholic beverages and in modern thermometers. Ethanol is one of the oldest recreational drugs...
. Carbonic maceration ferments most of the juice while it is still inside the grape, although grapes at the bottom of the vessel are crushed by gravity and undergo conventional fermentation.
Carbonic maceration is a
winemakingWinemaking, or vinification, is the production of wine, starting with selection of the grapes or other produce and ending with bottling the finished wine. Although most wine is made from grapes, it may also be made from other fruit or non-toxic plant material...
technique, often associated with the
French wineFrench wine is produced in several regions throughout France, in quantities between 50 and 60 million hectolitres per year . France has the world's largest wine production ahead of Italy and the second-largest total vineyard area behind Spain...
region of
BeaujolaisBeaujolais is a French Appellation d'Origine Contrôlée wine generally made of the Gamay grape which has a thin skin and few tannins. Like most AOC wines they are not labeled varietally. Whites from the region, which make up only 1% of its production, are made mostly with Chardonnay grapes though...
, in which whole grapes are
fermentedThe process of fermentation in wine is the catalyst function that turns grape juice into an alcoholic beverage. During fermentation yeast interact with sugars in the juice to create ethanol, commonly known as ethyl alcohol, and carbon dioxide...
in a
carbon dioxideCarbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state...
rich environment prior to crushing. Conventional
alcoholic fermentationEthanol fermentation is a biological process in which sugars such as glucose, fructose, and sucrose are converted into cellular energy and thereby produce ethanol and carbon dioxide as metabolic waste products....
involves crushing the grapes to free the juice and pulp from the skin with
yeastYeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with about 1,500 species currently described; they dominate fungal diversity in the oceans. Most reproduce asexually by budding, although a few do so by binary fission...
s serving as a the catalyst in converting
sugarSugar is a class of edible crystalline substances, mainly sucrose, lactose, and fructose. Human taste buds interpret its flavor as sweet. Sugar as a basic food carbohydrate primarily comes from sugar cane and from sugar beet, but also appears in fruit, honey, sorghum, sugar maple , and in many...
into
ethanolEthanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug, best known as the type of alcohol found in alcoholic beverages and in modern thermometers. Ethanol is one of the oldest recreational drugs...
. Carbonic maceration ferments most of the juice while it is still inside the grape, although grapes at the bottom of the vessel are crushed by gravity and undergo conventional fermentation. The resulting
wineWine is an alcoholic beverage typically made of fermented grape juice. The natural chemical balance of grapes is such that they can ferment without the addition of sugars, acids, enzymes or other nutrients. Wine is produced by fermenting crushed grapes using various types of yeast. Yeast consumes...
is fruity with very low
tanninTannins are astringent, bitter plant polyphenols that either bind and precipitate or shrink proteins. The astringency from the tannins is what causes the dry and puckery feeling in the mouth following the consumption of unripened fruit or red wine...
s. It is ready to drink quickly but lacks the structure for long-term aging. In the most extreme case, such as with
Beaujolais nouveauBeaujolais nouveau is a red wine made from Gamay grapes produced in the Beaujolais region of France. It is the most popular vin de primeur, fermented for just a few weeks then officially released for sale on the third Thursday of November...
, the period between picking and bottling can be less than six weeks.
Process
During carbonic maceration, an
anaerobicAnaerobic is a technical word which literally means without air , as opposed to aerobic.In wastewater treatment the absence of oxygen is indicated as anoxic; and anaerobic is used to indicate the absence of a common electron acceptor such as nitrate, sulphate or oxygen...
environment is created by pumping carbon dioxide into a sealed container filled with whole grape clusters. The carbon dioxide gas permeates through the grape skins and begins to stimulate fermentation at an
intracellularNot to be confused with intercellular, meaning "between cells".In cell biology, molecular biology and related fields, the word intracellular means "inside the cell".It is used in contrast to extracellular...
level. The entire process takes place inside each single, intact berry. Ethanol is produced as a by-product of this process but studies have shown that other unique chemical reactions take place that have a distinctive effect on the wine. Flavor compounds derived from volatile
phenolPhenol, also known as carbolic acid, is a toxic, white crystalline solid. Its chemical formula is C6H5OH and its structure is that of a hydroxyl group bonded to a phenyl ring, making it an aromatic compound.-Phenols:...
s like
benzaldehydeBenzaldehyde is an organic compound consisting of a benzene ring with a formyl substituent. It is the simplest aromatic aldehyde and one of the most industrially useful. This colorless liquid has a characteristic pleasant almond-like odor...
,
ethyl cinnamateEthyl cinnamate is the ester of cinnamic acid and ethanol. It is present in the essential oil of cinnamon ; pure ethyl cinnamate has a "fruity and balsamic odor, reminiscent of cinnamon with an amber note" ....
, ethyl vanillate, methyl vanillate and vinylbenzene emerge and are emphasized in the fruity flavors commonly associated with wines produced from carbonic maceration-like
bananaBanana is the common name for a herbaceous plants of the genus Musa, and the commonly eaten fruit it produces. They are native to the tropical region of Southeast Asia, and are likely to have been first domesticated in Papua New Guinea. Today, they are cultivated throughout the tropics.Banana...
and kirsch notes. While the levels of harsh
malic acidMalic acid is an organic compound with the formula HO
2CCH
2CHOHCO
2H. This dicarboxylic acid is the active ingredient in many sour or tart foods. Malic acid is found mostly in unripe fruits....
in the grape is decreased by 50%, the overall pH level increases by about 0.25
unitsA pH meter is an electronic instrument used to measure the pH of a liquid...
. The
glycerolGlycerol is an organic compound, also commonly called glycerin or glycerine. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydrophilic hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. ...
levels are increased ten folds and the grapes juices gain about 2% in potential alcoholic strength. The resulting wine is generally fruitier, with brighter coloring and less tannins than conventionally produced wines.
History
The process of carbonic maceration occurs naturally in a partial state without deliberate intervention and has occurred in some form throughout history. If grapes are stored in a close container, such as an oak barrel, the force of gravity will crush the grapes on the bottom, releasing grape juice. Ambient yeasts present on the grape skins will interact with the sugars in the grape juice to start conventional ethanol fermentation. Carbon dioxide is released as a by product and, being heavier than
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
, will push out the oxygen through any permeable surface (such as slight gaps between wood planks) creating a mostly anaerobic environment for the uncrushed grape clusters to go through carbonic maceration. Some of the earliest documented studies on the process was conducted by the French scientist
Louis PasteurLouis Pasteur was a French chemist and microbiologist born in Dole. He is best known for his remarkable breakthroughs in the causes and preventions of disease. His discoveries reduced mortality from puerperal fever, and he created the first vaccine for rabies. His experiments supported the germ...
who noted in 1872 that grapes contained in an oxygen rich environment prior to crushing and fermentation produced wines of different flavors than grapes produced in a carbon dioxide rich environment. This was because the fermentation process had already started within the individual grape clusters prior to the introduction of yeasts during conventional fermentation.
Wine production
The use of carbonic maceration is closely associated with the production of
Beaujolais nouveauBeaujolais nouveau is a red wine made from Gamay grapes produced in the Beaujolais region of France. It is the most popular vin de primeur, fermented for just a few weeks then officially released for sale on the third Thursday of November...
,
GamayGamay is a purple-colored grape variety used to make red wines, most notably grown in Beaujolais and in the Loire Valley around Tours. Its full name is Gamay Noir à Jus Blanc. It is a very old cultivar, mentioned as long ago as the 1400s...
wine in the Beaujolais region. The Gamay grape lends itself well to the production of simple, fruity wines and Beaujolais winemakers have been able to create a unique identity based on this distinctive style of wine.
Producers in other parts of
FranceFrance , officially the French Republic , is a country located in Western Europe, with several overseas islands and territories located on other continents. Metropolitan France extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean...
and in the
New WorldNew World wines are those wines produced outside the traditional wine-growing areas of Europe, in particular from Argentina, Australia, Canada, Chile, Mexico, New Zealand, South Africa and the United States.-History:...
have frequently utilized carbonic maceration for their own Gamay production, or with other
grape varieties. Winemakers in the
LanguedocLanguedoc - Roussillon wine, including the vin de pays labeled Vin de Pays d'Oc, is produced in southern France. While "Languedoc" can refer to a specific historic region of France and Northern Catalonia, usage since the 20th century has primarily referred to the northern part of the...
and Rhône wine regions will sometimes employ the technique on coarse and tannic grapes like Carignan, especially if they are to be blended with other varieties. In
AustraliaThe Australian wine industry is the fourth-largest exporter in the world, exporting over 400 million litres a year to a large international export market that includes "old world" wine-producing countries such as France, Italy and Spain. There is also a significant domestic market for Australian...
, a
proprietaryThe word proprietary indicates that a party, or proprietor, exercises private ownership, control or use over an item of property.Terms relating to Proprietary include:*Proprietary chapel*Proprietary church*Proprietary colleges*Proprietary colony...
line of "CabMac" wines was developed in the 1980s using carbonic maceration techniques on differing grape
varietal"Varietal" describes wines made primarily from a single named grape variety, and which typically displays the name of that variety on the wine label. Examples of grape varieties commonly used in varietal wines are Cabernet Sauvignon, Chardonnay and Merlot...
s. In California, the process is sometimes used with Valdiguié grapes, producing what is labeled a "
NouveauA nouveau, or vin primeur, is a French wine permitted by Appellation d'origine contrôlée regulations to be sold in the same year it was harvested. The most widely exported nouveau wine is Beaujolais nouveau which is released on the third Thursday of November, often only a few weeks after the...
" wine.
The process is almost always used in conjunction with red wine production since some of the flavors compounds produced by volatile
phenolsIn organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of a hydroxyl group bonded directly to an aromatic hydrocarbon group...
tend to form undesirable flavors with white wine
grape varieties.
Other techniques
Semi-carbonic maceration is the winemaking technique where grapes are put through a short period carbonic maceration, followed by conventional yeast fermentations. This is the process used in the production of Beaujolais nouveau wines. To an extent, most wines were historically treated to some form of semi or partial carbonic fermentation (as noted in history section above) with the amount dependent on the shape and size of the vessel that the grapes were stored in prior to crushing. The deeper the vessel, the greater the proportion of grapes that could be exposed to an anaerobic environment caused by the release of carbon dioxide from the crushed grapes on the bottom.
An alternative name for carbonic maceration is "whole grape fermentation" which is distinct from the process known as "whole bunch fermentation" which is common in the
Burgundy wineBurgundy wine is wine made in the Burgundy region in eastern France. The most famous wines produced here - those commonly referred to as Burgundies - are red wines made from Pinot Noir grapes or white wines made from Chardonnay grapes. Red and white wines are also made from other grape varieties,...
production of
Pinot noirPinot noir is a red wine grape variety of the species Vitis vinifera. The name may also refer to wines produced predominantly from Pinot noir grapes...
. With "whole bunch fermentation", entire clusters of grapes (including stems) are fermented before being crushed. This creates a large "cap" of grape skins with pathways created by the stems that allows juice to flow more evenly through caps, increasing the levels of skin contact or
macerationMaceration is the winemaking process where the phenolic materials of the grape— tannins, coloring agents and flavor compounds— are leached from the grape skins, seeds and stems into the must. The term is usually used in reference to wine, but is sometimes used with other drinks, such as...
.