Maceration is the

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 ...

process where the phenolic materials of the grape—

tannins 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'', f ...

, coloring agents (

anthocyanins Anthocyanins (), also called anthocyans, are water-soluble vacuolar pigments that, depending on their pH, may appear red, purple, blue, or black. In 1835, the German pharmacist Ludwig Clamor Marquart gave the name Anthokyan to a chemical com ...

) and flavor compounds—are leached from the grape skins, seeds and stems into the must. To macerate is to soften by soaking, and maceration is the process by which the red wine receives its red color, since raw grape juice (with the exceptions of

teinturier Teinturier grapes are grapes whose flesh and juice is red in colour due to anthocyanin pigments accumulating within the pulp of the grape berry itself. In most cases, anthocyanin pigments are confined to the outer skin tissue only, and the squee ...

s) is clear-grayish in color. In the production of white wines, maceration is either avoided or allowed only in very limited manner in the form of a short amount of skin contact with the juice prior to pressing. This is more common in the production of

varietal A varietal wine is a wine made primarily from a single named grape variety, and which typically displays the name of that variety on the wine label.The American Heritage Dictionary of the English Language, Fourth Edition, 2000.winepros.com.au. ...

s with less natural flavor and body structure like Sauvignon blanc and

Sémillon Sémillon is a golden-skinned grape used to make dry and sweet white wines, mostly in France and Australia. Its thin skin and susceptibility to botrytis make it dominate the sweet wine region Sauternes AOC and Barsac AOC. History The Sémil ...

. For Rosé, red wine grapes are allowed some maceration between the skins and must, but not to the extent of red wine production. While maceration is a technique usually associated with wine, it is used with other drinks, such as Lambic, piołunówka,

Campari Campari () is an Italian alcoholic liqueur, considered an apéritif (20.5%, 21%, 24%, 25%, or 28.5% ABV, depending on the country where it is sold), obtained from the infusion of herbs and fruit (including chinotto and cascarilla) in alcohol a ...

and

crème de cassis Crème de cassis () (also known as Cassis liqueur) is a sweet, dark red liqueur made from blackcurrants. Several cocktails are made with crème de cassis, including the popular wine cocktail, kir. It may also be served as an after-dinner liq ...

, and also used to steep unflavored spirit with herbs for making herb-based alcohol like absinthe.

Process

The process of maceration begins, to varying extent, as soon as the grapes' skins are broken and exposed to some degree of

heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is ...

Temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer. Thermometers are calibrated in various Conversion of units of temperature, temp ...

is the guiding force, with higher temperatures encouraging more breakdown and extraction of

phenols In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of one or more hydroxyl groups (— O H) bonded directly to an aromatic hydrocarbon group. The simplest is phenol, . Phenolic compounds are ...

from the skins and other grape materials. Maceration continues during the fermentation period, and can last well past the point when 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 ...

has converted all sugars into alcohol. The process itself is a slow one with compounds such as the anthocyanins needing to pass through the

cell membrane The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...

of the skins to come into contact with the wine. During fermentation, higher temperatures and higher alcohol levels can encourage this process with the alcohol acting as a

solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...

to assist in the breakdown of the

organic compounds In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The s ...

within the grape materials. This process seems to slow once the wine reaches an alcohol level of 10%. Throughout the fermentation process,

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...

is released as a byproduct of the conversion of sugar into alcohol. The carbon dioxide seeks to escape from the must by rising to the top of the mixture, pushing the grape skins and other materials to the top as well. This forms what is known as a ''cap'' that is visible on top of the fermentation vessel. At this point, a very limited amount of the must comes into contact with the skins, and winemakers seek to correct this by pushing down the cap (either with equipment or the traditional method of treading with their feet) or by pumping wine out from under and over onto the cap. This process of "pumping over" or "punching down" the cap is done often throughout the fermentation process, depending on the extent of maceration the winemaker desires. An efficient and modern method of maceration is the "pneumatage process" in which compressed air or gas is sequentially injected into the juice. The bubbles created during the pneumatage process uses gravity and the weight of the juice to circulate the wine juice with the cap of skins and grape solids allowing for greater extraction of aroma, coloring agents and tannins to diffuse into the wine juice ("must").

Benefits

Teinturier Agria and peeled Grenache grape

Depending on the varietal, the process of maceration can help bring out many flavors in the wine that would otherwise be lacking. It can enhance the body and

mouthfeel Mouthfeel refers to the physical sensations in the mouth caused by food or drink, making it distinct from taste. It is a fundamental sensory attribute which, along with taste and smell, determines the overall flavor of a food item. Mouthfeel ...

for many wines, as well as strengthen the color. Greater extraction can add to the complexity and life expectancy of the wine by developing more complex tannins that will soften over a longer period of time. With these benefits does come the risk of developing various

wine fault 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 ...

s, such as the development of acetic (or "volatile") acidity. Too much extraction can also increase the harshness of some tannins to where the wine is not very approachable to most wine drinkers.

Other processes

One classical method of maceration is grape treading or ''pigeage'', where grapes are crushed in vats by barefoot workers. The process of cold maceration or cold soak is where temperatures of the fermenting must are kept low to encourage extraction by water and added sulfur dioxide rather than relying principally on heat and alcohol to act as a solvent. This technique was popular in the production of

Burgundy wine Burgundy wine ( or ') is made in the Burgundy region of eastern France, in the valleys and slopes west of the Saône, a tributary of the Rhône. The most famous wines produced here, and those commonly referred to as "Burgundies," are dry red win ...

s in the 1970s and 1980s but there is still some debate among oenologists about the overall benefits to and resulting quality of the wine.

Carbonic maceration Carbonic maceration is a winemaking technique, often associated with the French wine region of Beaujolais, in which whole grapes are fermented in a carbon dioxide rich environment before crushing. Conventional alcoholic fermentation involves cru ...

is the fermentation of whole clusters of unbroken grapes in an atmosphere saturated with

, which prevents traditional yeast fermentation. It is a process different from what is commonly referred to in winemaking as "maceration".

References

{{Winemaking Winemaking Wine terminology de:Mazeration fr:Macération