Maceration is the winemaking process where the phenolic materials of the grape— tannins, coloring agents ( anthocyanins) and flavor compounds—are leached from the grape skins, seeds and stems into the

must Must is freshly crushed Juice, fruit juice (usually grape juice) that contains the skins, seeds, and stems of the fruit. The solid portion of the must is called pomace and typically makes up 7–23% of the total weight of the must. Making 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 teinturiers) 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 varietals with less natural flavor and body structure like Sauvignon blanc and Sémillon. For

Rosé A rosé () is a type of wine that incorporates some of the wine color, color from the grape skins, but not enough to qualify it as a red wine. It may be the oldest known type of wine, as it is the most straightforward to make with the Macerati ...

, 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 Lambic ( , ; ) is a type of beer brewed in the Pajottenland region of Belgium southwest of Brussels since the 13th century. Types of lambic beer include gueuze, kriek lambic, and framboise. Lambic differs from most other beers in that it is Bre ...

, piołunówka, Campari and crème de cassis, 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 energy in transfer between a thermodynamic system and its surroundings by such mechanisms as thermal conduction, electromagnetic radiation, and friction, which are microscopic in nature, involving sub-atomic, ato ...

Temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...

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 ar ...

from the skins and other grape materials. Maceration continues during the

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 ...

period, and can last well past the point when 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 ...

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 or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extr ...

of the skins to come into contact with the wine. During fermentation, higher temperatures and higher

alcohol Alcohol may refer to: Common uses * Alcohol (chemistry), a class of compounds * Ethanol, one of several alcohols, commonly known as alcohol in everyday life ** Alcohol (drug), intoxicant found in alcoholic beverages ** Alcoholic beverage, an alco ...

levels can encourage this process with the alcohol acting as a

solvent A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...

to assist in the breakdown of the

organic compounds Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

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 is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

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 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 faults, 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 Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...

rather than relying principally on heat and alcohol to act as a solvent. This technique was popular in the production of Burgundy wines 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 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