Oak is 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 vary the color, flavor,
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'', ...
profile and texture of wine. It can be introduced in the form of a
barrel
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, ...
during the
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 ...
or
aging
Ageing ( BE) or aging ( AE) is the process of becoming older. The term refers mainly to humans, many other animals, and fungi, whereas for example, bacteria, perennial plants and some simple animals are potentially biologically immortal. In ...
periods, or as free-floating chips or
staves added to wine fermented in a vessel like stainless steel. Oak barrels can impart other qualities to wine through
evaporation
Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...
and low level exposure to
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 as wel ...
.
[J. Robinson ''Jancis Robinson's Wine Course'' Third Edition pg 91-93 Abbeville Press 2003 ]
History
![Barrel fermented California Chard](https://upload.wikimedia.org/wikipedia/commons/e/ee/Barrel_fermented_California_Chard.jpg)
In early
wine history, the
amphora
An amphora (; grc, ἀμφορεύς, ''amphoreús''; English plural: amphorae or amphoras) is a type of container with a pointed bottom and characteristic shape and size which fit tightly (and therefore safely) against each other in storag ...
was the vessel of choice for the
storage
Storage may refer to:
Goods Containers
* Dry cask storage, for storing high-level radioactive waste
* Food storage
* Intermodal container, cargo shipping
* Storage tank
Facilities
* Garage (residential), a storage space normally used to store car ...
and transportation of wine. Due to the perishable nature of wood material it is difficult to trace the usage of
barrel
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, ...
s in history. The Greek historian
Herodotus
Herodotus ( ; grc, , }; BC) was an ancient Greek historian and geographer from the Greek city of Halicarnassus, part of the Persian Empire (now Bodrum, Turkey) and a later citizen of Thurii in modern Calabria ( Italy). He is known f ...
noted that ancient
Mesopotamians
Mesopotamia ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن or ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in the northern part of the F ...
used barrels made of
palm wood
The Arecaceae is a family of perennial flowering plants in the monocot order Arecales. Their growth form can be climbers, shrubs, tree-like and stemless plants, all commonly known as palms. Those having a tree-like form are called palm trees. ...
to transport wine along the
Euphrates
The Euphrates () is the longest and one of the most historically important rivers of Western Asia. Tigris–Euphrates river system, Together with the Tigris, it is one of the two defining rivers of Mesopotamia ( ''the land between the rivers'') ...
. Palm is a difficult material to bend and fashion into barrels, however, and wine merchants in different regions experimented with different wood styles to find a better wood source.
[H. Johnson ''Vintage: The Story of Wine'' pg 25-26 Simon and Schuster 1989 ] The use of oak has been prevalent in winemaking for at least two
millennia
A millennium (plural millennia or millenniums) is a period of one thousand years, sometimes called a kiloannum (ka), or kiloyear (ky). Normally, the word is used specifically for periods of a thousand years that begin at the starting point (ini ...
, first coming into widespread use during the time of the
Roman Empire
The Roman Empire ( la, Imperium Romanum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post-Republican period of ancient Rome. As a polity, it included large territorial holdings around the Mediterr ...
. In time, winemakers discovered that beyond just storage convenience, wine kept in oak barrels took on properties that improved it by making it softer and, in some cases, better-tasting.
[K. MacNeil ''The Wine Bible'' pg 40 Workman Publishing 2001 ]
Effects on wine
The porous nature of an oak barrel allows evaporation and
oxygenation
Oxygenation may refer to:
* Oxygenation (environmental), a measurement of dissolved oxygen concentration in soil or water
* Oxygen saturation (medicine), the process by which concentrations of oxygen increase within a tissue
* Water oxygenation, t ...
to occur in wine but typically not at levels that would cause
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 a d ...
or
spoilage. The typical 59-
gallon
The gallon is a unit of volume in imperial units and United States customary units. Three different versions are in current use:
*the imperial gallon (imp gal), defined as , which is or was used in the United Kingdom, Ireland, Canada, Austral ...
(225-liter) barrel can lose anywhere from 5 to 6 gallons (21 to 25 liters) (of mostly
alcohol
Alcohol most commonly refers to:
* Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom
* Alcohol (drug), an intoxicant found in alcoholic drinks
Alcohol may also refer to:
Chemicals
* Ethanol, one of sev ...
and
water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
) in a year through evaporation. This allows the wine to concentrate its
flavor
Flavor or flavour is either the sensory perception of taste or smell, or a flavoring in food that produces such perception.
Flavor or flavour may also refer to:
Science
*Flavors (programming language), an early object-oriented extension to Lis ...
and
aroma compounds
An aroma compound, also known as an odorant, aroma, fragrance or flavoring, is a chemical compound that has a smell or odor. For an individual chemical or class of chemical compounds to impart a smell or fragrance, it must be sufficiently vo ...
. Small amounts of
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 as wel ...
are allowed to pass through the barrel and act as a softening agent upon the wine's
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'', ...
s.
The chemical properties of oak can have a profound effect on wine.
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 c ...
within the wood interact to produce
vanilla
Vanilla is a spice derived from orchids of the genus ''Vanilla (genus), Vanilla'', primarily obtained from pods of the Mexican species, flat-leaved vanilla (''Vanilla planifolia, V. planifolia'').
Pollination is required to make the p ...
type flavors and can give the impression of tea notes or sweetness. The degree of "toast" on the barrel can also impart different properties affecting the tannin levels as well as the aggressive wood flavors.
[K. MacNeil ''The Wine Bible'' pg 41 Workman Publishing 2001 ] The
hydrolyzable tannin
A hydrolyzable tannin or pyrogallol-type tannin is a type of tannin that, on heating with hydrochloric or sulfuric acids, yields gallic or ellagic acids.
At the center of a hydrolyzable tannin molecule, there is a carbohydrate (usually D-glucose ...
s present in wood, known as
ellagitannins
The ellagitannins are a diverse class of hydrolyzable tannins, a type of polyphenol formed primarily from the oxidative linkage of galloyl groups in 1,2,3,4,6-pentagalloyl glucose. Ellagitannins differ from gallotannins, in that their galloyl group ...
, are derived from
lignin
Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...
structures in the wood. They help protect the wine from oxidation and
reduction.
[J. Robinson (ed) ''"The Oxford Companion to Wine"'' Third Edition pg 492 Oxford University Press 2006 ]
![FLOR-ValdiviaJerez59](https://upload.wikimedia.org/wikipedia/commons/0/0a/FLOR-ValdiviaJerez59.jpg)
Characteristics of white wines fermented in oak include a pale color and extra silky texture. White wines fermented in steel and matured in oak will have a darker coloring due to heavy
phenolic
Phenolic is an adjective and a substantive (noun) that may apply to :
* Phenol (or carbolic acid), a colorless crystalline solid and aromatic compound
* Phenols, a class of chemical compounds that include phenol
* Phenolic content in wine
* Phenol ...
compounds still present.
[J. Robinson ''Jancis Robinson's Wine Course'' Third Edition pg 93 Abbeville Press 2003 ] Flavor notes commonly used to describe wines exposed to oak include
caramel
Caramel ( or ) is an orange-brown confectionery product made by heating a range of sugars. It can be used as a flavoring in puddings and desserts, as a filling in bonbons, or as a topping for ice cream and custard.
The process of caramelizatio ...
,
cream
Cream is a dairy product composed of the higher-fat layer skimmed from the top of milk before homogenization. In un-homogenized milk, the fat, which is less dense, eventually rises to the top. In the industrial production of cream, this process ...
,
smoke
Smoke is a suspension of airborne particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-product ...
,
spice
A spice is a seed, fruit, root, bark, or other plant substance primarily used for flavoring or coloring food. Spices are distinguished from herbs, which are the leaves, flowers, or stems of plants used for flavoring or as a garnish. Spices a ...
and vanilla.
Chardonnay
Chardonnay (, , ) is a green-skinned grape variety used in the production of white wine. The variety originated in the Burgundy wine region of eastern French wine, France, but is now grown wherever wine is produced, from English wine, Englan ...
is a varietal with very distinct flavor profiles when fermented in oak, which include
coconut
The coconut tree (''Cocos nucifera'') is a member of the palm tree family ( Arecaceae) and the only living species of the genus ''Cocos''. The term "coconut" (or the archaic "cocoanut") can refer to the whole coconut palm, the seed, or the ...
,
cinnamon
Cinnamon is a spice obtained from the inner bark of several tree species from the genus ''Cinnamomum''. Cinnamon is used mainly as an aromatic condiment and flavouring additive in a wide variety of cuisines, sweet and savoury dishes, breakfa ...
and
cloves
Cloves are the aromatic flower buds of a tree in the family Myrtaceae, ''Syzygium aromaticum'' (). They are native to the Maluku Islands (or Moluccas) in Indonesia, and are commonly used as a spice, flavoring or fragrance in consumer products, s ...
notes. The "toastiness" of the barrel can bring out varying degrees of
mocha and
toffee
Toffee is a confection made by caramelizing sugar or molasses (creating inverted sugar) along with butter, and occasionally flour. The mixture is heated until its temperature reaches the hard crack stage of . While being prepared, toffee is ...
notes in red wine.
[D. Sogg]
White Wines, New Barrels: The taste of new oak gains favor worldwide
" Wine Spectator July 31, 2001 It is a common misconception that oak imparts butter flavors to wine. The butter flavors come from
lactic acid
Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as natu ...
, naturally present in the wine, converted during malolactic fermentation to
diacetyl
Diacetyl (IUPAC systematic name: butanedione or butane-2,3-dione) is an organic compound with the chemical formula (CH3CO)2. It is a yellow liquid with an intensely buttery flavor. It is a vicinal diketone (two C=O groups, side-by-side). Diacet ...
. This process reverses itself, although the addition of sulfur dioxide prevents this, and the diacetyl remains.
Wines can be
barrel fermented in oak or placed in oak after fermentation for a period of aging or maturation. Wine matured in oak receives more oak flavors and properties than wine fermented in oak because
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 constitut ...
cells present in fermentation interact with and "latch on" to oak components. When dead yeast cells are removed as
lees some oak properties go with them.
[K. MacNeil ''The Wine Bible'' pg 45 Workman Publishing 2001 ]
The length of time a wine spends in the barrel is dependent on the
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. ...
and finished style the winemaker desires. The majority of oak flavoring is imparted in the first few months the wine is in contact with oak, while longer term exposure adds light barrel
aeration
Aeration (also called aerification or aeriation) is the Systems engineering process, process by which air is circulated through, mixed with or solvation, dissolved in a liquid or other substances that act as a fluid (such as soil). Aeration proces ...
, which helps precipitate phenolic compounds and quickens the aging process.
New World
The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. 3 ...
Pinot noir
Pinot Noir () is a red-wine grape variety of the species ''Vitis vinifera''. The name may also refer to wines created predominantly from pinot noir grapes. The name is derived from the French language, French words for ''pine'' and ''black.' ...
may spend less than a year in oak. Premium
Cabernet Sauvignon
Cabernet Sauvignon () is one of the world's most widely recognized red wine grape varieties. It is grown in nearly every major wine producing country among a diverse spectrum of climates from Australia and British Columbia, Canada to Lebanon' ...
may spend two years. The very tannic
Nebbiolo
Nebbiolo (, ; pms, nebieul ) is an Italian red wine grape variety predominantly associated with its native Piedmont region, where it makes the ''Denominazione di Origine Controllata e Garantita'' (DOCG) wines of Barolo, Barbaresco, Roero, G ...
grape may spend four or more years in oak. High end
Rioja producers will sometimes
age
Age or AGE may refer to:
Time and its effects
* Age, the amount of time someone or something has been alive or has existed
** East Asian age reckoning, an Asian system of marking age starting at 1
* Ageing or aging, the process of becoming older ...
their wines up to ten years in American oak to get a desired earthy cedar and herbal character.
Oak types and sources
The species of oak typically used for American oak production is the ''
Quercus alba
An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably '' ...
'' which is a white oak species that is characterized by its relatively fast growth, wider grains and lower wood tannins. It is found in most of the
Eastern United States
The Eastern United States, commonly referred to as the American East, Eastern America, or simply the East, is the region of the United States to the east of the Mississippi River. In some cases the term may refer to a smaller area or the East C ...
as well as
Missouri
Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...
,
Minnesota
Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...
and
Wisconsin
Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...
where many wine barrels are from. In
Oregon
Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
the ''
Quercus garryana
''Quercus garryana'' is an oak tree species of the Pacific Northwest, with a range stretching from southern California to southwestern British Columbia. It is commonly known as the Oregon white oak or Oregon oak or, in Canada, the Garry oak. It ...
'' white oak has started to gain usage due to its closer similarities to European oak.
In France, both the ''
Quercus robur
''Quercus robur'', commonly known as common oak, pedunculate oak, European oak or English oak, is a species of flowering plant in the beech and oak family, Fagaceae. It is a large tree, native plant, native to most of Europe west of the Caucasus ...
'' (common oak) and ''
Quercus petraea
''Quercus petraea'', commonly known as the sessile oak, Cornish oak, Irish Oak or durmast oak, is a species of oak tree native to most of Europe and into Anatolia and Iran. The sessile oak is the national tree of Ireland, and an unofficial emble ...
'' (white oak) are considered apt for wine making; however, the latter is considered far superior for its finer grain and richer contribution of aromatic components like
vanillin
Vanillin is an organic compound with the molecular formula . It is a phenolic aldehyde. Its functional groups include aldehyde, hydroxyl, and ether. It is the primary component of the extract of the vanilla bean. Synthetic vanillin is now used ...
and its derivates, methyl-octalactone and tannins, as well as phenols and volatile aldehydes.
French oak typically comes from one or more primary forests:
Allier
Allier ( , , ; oc, Alèir) is a department in the Auvergne-Rhône-Alpes region that borders Cher to the west, Nièvre to the north, Saône-et-Loire and Loire to the east, Puy-de-Dôme to the south, and Creuse to the south-west. Named afte ...
,
Limousin
Limousin (; oc, Lemosin ) is a former administrative region of southwest-central France. On 1 January 2016, it became part of the new administrative region of Nouvelle-Aquitaine. It comprised three departments: Corrèze, Creuse, and Haute-Vienn ...
,
Nevers
Nevers ( , ; la, Noviodunum, later ''Nevirnum'' and ''Nebirnum'') is the prefecture of the Nièvre Departments of France, department in the Bourgogne-Franche-Comté Regions of France, region in central France. It was the principal city of the ...
,
Tronçais and
Vosges
The Vosges ( , ; german: Vogesen ; Franconian and gsw, Vogese) are a range of low mountains in Eastern France, near its border with Germany. Together with the Palatine Forest to the north on the German side of the border, they form a single ...
. The wood from each of these forests has slightly different characteristics. Many winemakers utilize barrels made from different cooperages, regions and degrees of toasting in blending their wines to enhance the complexity of the resulting wine.
[T. Stevenson ''"The Sotheby's Wine Encyclopedia"'' pg 33-34 Dorling Kindersley 2005 ]
Italian wine
Italian wine is produced in every region of Italy. Italy is the world's largest producer of wine, with an area of under vineyard cultivation, and contributing a 2013–2017 annual average of 48.3 million hl of wine. In 2018 Italy accounted for ...
makers have had a long history of using
Slavonia
Slavonia (; hr, Slavonija) is, with Dalmatia, Croatia proper, and Istria, one of the four historical regions of Croatia. Taking up the east of the country, it roughly corresponds with five Croatian counties: Brod-Posavina, Osijek-Baranja ...
n oak from the ''
Quercus robur
''Quercus robur'', commonly known as common oak, pedunculate oak, European oak or English oak, is a species of flowering plant in the beech and oak family, Fagaceae. It is a large tree, native plant, native to most of Europe west of the Caucasus ...
'' which is known for its tight grain, low aromatics and medium level tannins. Slavonian oak tends to be used in larger barrel sizes (with less surface area relative to volume) with the same barrels reused for many more years before replacement. Prior to the
Russian Revolution
The Russian Revolution was a period of Political revolution (Trotskyism), political and social revolution that took place in the former Russian Empire which began during the First World War. This period saw Russia abolish its monarchy and ad ...
, ''Quercus petraea'' oak from Hungary was the most highly sought after wood for
French wine
French wine is produced all throughout France, in quantities between 50 and 60 million hectolitres per year, or 7–8 billion bottles. France is one of the largest wine producers in the world, along with Italian, Spanish, and America ...
making. The trees in the Hungarian Zemplén Mountains grow more slowly and smaller in the volcanic soil, creating fine tight grain which sequentially lends itself to a very delicate extraction.
The hemicellulose in the Hungarian oak breaks down more easily, and conveys an exceptional selection of toasted, vanilla, sugary, woody, spicy and caramel-like flavors – imparting these aromas with less intensity, and more slowly than American or French oak.
Many winemakers favor the softer, smoother, creamier texture that Hungarian oak offers their wines. French winemakers preferred to use Hungarian barrels until the early 20th century, then – because of world wars, supply cut – the French wine industry was forced to find its own source in France, similar to the unique quality, legendary Hungarian Zemplén oak.
However, after the fall of the Iron Curtain, the cooperages from France again became major consumers of the exclusive ''Quercus petraea''/Sessile Hungarian Oak trees originating in the Zemplén Mountain Forest.
The Russian oak from the
Adygey region along the
Black Sea
The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Roma ...
is being explored by French winemakers as a cheaper alternative to French and Hungarian oak.
Canadian wine
Canadian wine is wine produced in Canada. Ontario and British Columbia are the two largest wine-producing provinces in Canada, with two-thirds of the Canada's vineyard acreage situated in Ontario. However, wine producing regions are also present i ...
ries have been experimenting with the use of Canadian oak, which proponents describe as a middle ground between American and French oak even though it is the same species as American oak.
Oak trees are typically between 80–120 years old prior to harvesting with the ideal conditions being a cool climate in a dense forest region that gives the trees opportunity to mature slowly and develop a tighter grain. Typically one tree can provide enough wood for two barrels. The trees are typically
harvest
Harvesting is the process of gathering a ripe crop from the fields. Reaping is the cutting of grain or pulse for harvest, typically using a scythe, sickle, or reaper. On smaller farms with minimal mechanization, harvesting is the most labor-i ...
ed in the winter months when there is less
sap
Sap is a fluid transported in xylem cells (vessel elements or tracheids) or phloem sieve tube elements of a plant. These cells transport water and nutrients throughout the plant.
Sap is distinct from latex, resin, or cell sap; it is a separa ...
in the trunk.
[J. Robinson ''Jancis Robinson's Wine Course'' Third Edition pg 92 Abbeville Press 2003 ]
Differences between French and American oak
![500 litres oak barrels Bodegas Casajus Ribera del Duero](https://upload.wikimedia.org/wikipedia/commons/4/42/500_litres_oak_barrels_Bodegas_Casajus_Ribera_del_Duero.jpg)
American oak tends to be more intensely flavored than French oak with more sweet and
vanilla
Vanilla is a spice derived from orchids of the genus ''Vanilla (genus), Vanilla'', primarily obtained from pods of the Mexican species, flat-leaved vanilla (''Vanilla planifolia, V. planifolia'').
Pollination is required to make the p ...
overtones due to the American oak having two to four times as many
lactones
Lactones are cyclic carboxylic esters, containing a 1-oxacycloalkan-2-one structure (), or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring.
Lactones are formed by intramolecular esterification of the co ...
.
Winemakers choose American oak typically for bold, powerful reds, base wines for "assemblage", or for warm climate
Chardonnay
Chardonnay (, , ) is a green-skinned grape variety used in the production of white wine. The variety originated in the Burgundy wine region of eastern French wine, France, but is now grown wherever wine is produced, from English wine, Englan ...
s. Besides being derived from different species, a major difference between American and French oak comes from the preparation of the wood. The tighter
grain
A grain is a small, hard, dry fruit (caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legum ...
and less watertight nature of French oak obliges
coopers to split the wood along the grain. The wood is then aged or "seasoned" for 24 to 36 months in the open air, in a so-called wood-yard.
![Toneleria-nacional-wood-yard](https://upload.wikimedia.org/wikipedia/commons/9/97/Toneleria-nacional-wood-yard.png)
Even though American coopers may use a
kiln
A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for millennia to turn objects made from clay int ...
-dry method to season the wood, almost all others will season American oak in exactly the same way as French.
Open air seasoning has the advantage of leaching undesirable chemical components and bitter tannins, mellowing the oak in a manner that kiln-dry methods are incapable of replicating.
Even though sun, rain, and wind may suffice in most cases to season oak, in drier climates coopers - such as
Tonelería Nacional - apply up to 2000 mm (80 in) of water a year to their wood stacks in order to facilitate the seasoning process.
Since French oak must be split, only 20 to 25% of the tree can be utilized; American oak may be sawn, which makes it at least twice as economical. Its more pronounced oxidation and a quicker release of aromas help wines to lose their astringency and harshness more quickly, which makes this the wood of choice for shorter maturations - six to ten months. Because of American oak’s modest tannin contribution, the perfect first fill is a wine with abundant tannins and good texture; it allows the fruit to interact harmoniously with the wood, which contributes a wide array of complex aromas and soft, yet very palatable tannins.
French oak, on the other hand, generates silky and transparent tannins, which transmit a sensation of light sweetness combined with fruity flavors that persist in the mouth. Spices and toasted almond are noteworthy, combined with flavors of ripe red fruit in red wines, and notes of peach, exotic fruits and floral aromas like jasmine and rose in whites, depending on the grape variety employed.
Wine barrel
![Rutherford Hill Wine Cave-1369](https://upload.wikimedia.org/wikipedia/commons/b/b3/Rutherford_Hill_Wine_Cave-1369.jpg)
Wine barrels, especially those made of oak, have long been used as containers in which wine is aged. Aging in oak typically imparts desirable vanilla and spice flavors to wine. The size of the barrel plays a large role in determining the effects of oak on the wine by dictating the ratio of surface area to volume of wine with smaller containers having a larger impact. The most common barrels are the Bordeaux style barrel, which holds , followed by the Burgundy style barrel, which holds . Some New World winemakers are now also using the larger
hogshead
A hogshead (abbreviated "hhd", plural "hhds") is a large cask of liquid (or, less often, of a food commodity). More specifically, it refers to a specified volume, measured in either imperial or US customary measures, primarily applied to alcoho ...
barrel.
Larger barrels are also traditionally used in parts of Italy such as Barolo,
[J Wheaver]
2006 as well as the south of France.
New barrels impart more flavors than do previously used barrels. Over time many of the oak properties get "leached" out of the barrel with layers of natural deposits left from the wine building up on the wood to where after 3 to 5
vintages
Vintage, in winemaking, is the process of picking grapes and creating the finished product—wine (see Harvest (wine)). A vintage wine is one made from grapes that were all, or primarily, grown and harvested in a single specified year. In certa ...
there may be little or no oak flavors imparted on the wine.
In addition, oxygen transport through the oak and into the wine, which is required for maturation, becomes severely limited after 3–5 years. The cost of barrels varies due to the
supply and demand
In microeconomics, supply and demand is an economic model of price determination in a Market (economics), market. It postulates that, Ceteris paribus, holding all else equal, in a perfect competition, competitive market, the unit price for a ...
market economy and can change with different features that a cooperage may offer. As of late 2007 the price for a standard American oak barrel was US$600 to 800, French oak US$1200 and up, and Eastern European US$600. Due to the expense of barrels, several techniques have been devised in an attempt to save money. One is to shave the inside of used barrels and insert new thin inner staves that have been toasted.
[D. Sogg]
Oak Flavorings
" Wine Spectator Sept.20th, 2002
Barrel construction
Barrels are constructed in
cooperages
A cooper is a person trained to make wooden casks, barrels, vats, buckets, tubs, troughs and other similar containers from timber staves that were usually heated or steamed to make them pliable.
Journeymen coopers also traditionally made ...
. The traditional method of European coopers has been to hand-split the oak into staves (or strips) along the grain. After the oak is split, it is allowed to "season" or dry outdoors while exposed to the elements. This process can take anywhere from 10 to 36 months during which time the harshest tannins from the wood are leached out. These tannins are visible as dark gray and black residue left on the ground once the staves are removed. The longer the wood is allowed to season the softer the potential wine stored in the barrels may be but this can add substantially to the cost of the barrel. In some American cooperage the wood is dried in a
kiln
A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for millennia to turn objects made from clay int ...
instead of outdoor seasoning. While this method is much faster, it does not soften the tannins quite as much as outdoor seasoning.
[K. MacNeil ''The Wine Bible'' pg 42-43 Workman Publishing 2001 ]
The staves are then heated, traditionally over an open fire, and, when