Oak is used in winemaking to vary the color, flavor, tannin profile and texture of wine. It can be introduced in the form of a barrel during the fermentation or aging 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 and low level exposure to oxygen. [1]
In early wine history, the amphora was the vessel of choice for the storage and transportation of wine. Due to the perishable nature of wood material it is difficult to trace the usage of barrels in history. The Greek historian Herodotus noted that ancient Mesopotamians used barrels made of palm wood to transport wine along the Euphrates. 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. [2] The use of oak has been prevalent in winemaking for at least two millennia, first coming into widespread use during the time of the Roman Empire. 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. [3]
The porous nature of an oak barrel allows evaporation and oxygenation to occur in wine but typically not at levels that would cause oxidation or spoilage. The typical 59-gallon (225-liter) barrel can lose anywhere from 51⁄2 to 61⁄2 gallons (21 to 25 liters) (of mostly alcohol and water) in a year through evaporation. This allows the wine to concentrate its flavor and aroma compounds. Small amounts of oxygen are allowed to pass through the barrel and act as a softening agent upon the wine's tannins. [3]
The chemical properties of oak can have a profound effect on wine. Phenols within the wood interact to produce vanilla 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. [4] The hydrolyzable tannins present in wood, known as ellagitannins, are derived from lignin structures in the wood. They help protect the wine from oxidation and reduction. [5]
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 compounds still present. [6] Flavor notes commonly used to describe wines exposed to oak include caramel, cream, smoke, spice and vanilla. Chardonnay is a varietal with very distinct flavor profiles when fermented in oak, which include coconut, cinnamon and cloves notes. The "toastiness" of the barrel can bring out varying degrees of mocha and toffee notes in red wine. [7] It is a common misconception that oak imparts butter flavors to wine. The butter flavors come from lactic acid, naturally present in the wine, converted during malolactic fermentation to diacetyl. 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 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. [8]
The length of time a wine spends in the barrel is dependent on the varietal 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, which helps precipitate phenolic compounds and quickens the aging process. [6] New World Pinot noir may spend less than a year in oak. Premium Cabernet Sauvignon may spend two years. The very tannic Nebbiolo grape may spend four or more years in oak. High end Rioja producers will sometimes age their wines up to ten years in American oak to get a desired earthy cedar and herbal character. [8]
The species of oak typically used for American oak production is the Quercus alba 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 as well as Missouri, Minnesota and Wisconsin where many wine barrels are from. In Oregon the Quercus garryana white oak has started to gain usage due to its closer similarities to European oak.
In France, both the Quercus robur (English oak) and Quercus petraea (sessile 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 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, Limousin, Nevers, Tronçais and Vosges. 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. [9]
Italian winemakers have had a long history of using Slavonian oak from the Quercus robur 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. [10] Prior to the Russian Revolution, Quercus petraea oak from Hungary was the most highly sought after wood for French winemaking. 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. [11]
The Russian oak from the Adygey region along the Black Sea is being explored by French winemakers as a cheaper alternative to French and Hungarian oak. [12] Canadian wineries 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. [13]
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 225-litre (59 US gal) barrels. The trees are typically harvested in the winter months when there is less sap in the trunk. [11]
American oak tends to be more intensely flavored than French oak with more sweet and vanilla overtones due to the American oak having two to four times as many lactones. [7] Winemakers choose American oak typically for bold, powerful reds, base wines for "assemblage", or for warm climate Chardonnays. Besides being derived from different species, a major difference between American and French oak comes from the preparation of the wood. The tighter grain 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.
Even though American coopers may use a kiln-dry method to season the wood, almost all others will season American oak in exactly the same way as French. [11] 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. [7] 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 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 225 litres (59 US gal), followed by the Burgundy style barrel, which holds 228 litres (60 US gal). Some New World winemakers are now also using the larger hogshead 300-litre (79 US gal) barrel. [6] Larger barrels are also traditionally used in parts of Italy such as Barolo, [14] 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 there may be little or no oak flavors imparted on the wine. [4] 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 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. [15] 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. [16]
Barrels are constructed in cooperages. 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 instead of outdoor seasoning. While this method is much faster, it does not soften the tannins quite as much as outdoor seasoning. [17]
The staves are then heated, traditionally over an open fire, and, when pliable, are bent into the desired shape of the barrel and held together with iron rings. Instead of fire, a cooper may use steam to heat up the staves but this tends to impart less "toastiness" and complexity to the resulting wine. Following the traditional, hand worked style, a cooper is typically able to construct one barrel in a day's time. Winemakers can order barrels with the wood on the inside of the barrel having been lightly charred or toasted with fire, medium toasted, or heavily toasted. [17] Typically the "lighter" the toasting the more oak flavor and tannins that are imparted. Heavy toast or "charred" which is typical treatment of barrels in Burgundy wine have an added dimension from the char that medium or light toasted barrels do not impart. [6] Heavy toasting dramatically reduces the coconut note lactones, even in American oak, but create a high carbon content that may reduce the coloring of some wines. During the process of toasting, the furanic aldehydes in the wood reach a higher level of concentration. This produces the "roasted" aroma in the wine. The toasting also enhances the presences of vanillin and the phenol eugenol which creates smokey and spicy notes that in some wines are similar to the aromatics of oil of cloves. [18]
Although oak barrels have long been used by winemakers, many wineries now use oak wood chips for aging wine more quickly and also adding desired woody aromas along with vanilla flavors. Oak chips can be added during fermentation or during aging. In the latter case, they are generally placed into fabric sacks and placed into the aging wine. The diversity of chips available gives winemakers numerous options. Oak chips have the benefit of imparting intense oak flavoring in a matter of weeks while traditional oak barrels would need a year or more to convey similar intensity. Critics claim that the oak flavoring from chips tend to be one-dimensional and skewed towards the vanilla extract with the wines still lacking some of the physical benefits that barrel oak imparts. [16] The use of oak powder is also less common than chips, although they are a very practical alternative if oak character is to be introduced during fermentation. Oak planks or staves are sometimes used, either during fermentation or aging. Wines made from these barrel alternatives typically do not age as well as wines that are matured in barrels. [6] Improvements in micro-oxygenation have allowed winemakers to better mimic the gentle aeration of oak barrels in stainless steel tanks with oak chips. [19]
Prior to 2006, the practice of using oak chips was outlawed in the European Union. [20] In 1999, the Bordeaux court of appeals fined four wineries, including third growth Chateau Giscours, over $13,000 USD for the use of oak chips in their wine. [21]
Throughout history other wood types, including chestnut, pine, redwood, and black locust, have been used in crafting winemaking vessels, particularly large fermentation vats. However, none of these wood types possess the compatibility with wine that oak has demonstrated in combining its water tight, yet slightly porous, storage capabilities with the unique flavor and texture characteristic that it can impart to the wine that it is in contact with. [22] Chestnut is very high in tannins and is too porous as a storage barrel and must be coated with paraffin to prevent excessive wine loss through evaporation. Redwood is too rigid to bend into the smaller barrel shapes and imparts an unpleasant flavor. Black Locust imparts a yellow tint to the wine. Other hardwoods like apple and cherry wood have an off putting smell. [23] Austrian winemakers have a history of using black locust barrels. Historically, chestnut was used by Beaujolais, Italian and Portuguese wine makers. [24] Some Rhône winemakers still use paraffin coated chestnut barrels but the coating minimizes any effect from the wood making its function similar to a neutral concrete vessel. In Chile there are traditions for using barrels made of rauli wood but it is beginning to fall out of favor due to the musky scent it imparts on wine. [25]
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's Beqaa Valley. Cabernet Sauvignon became internationally recognized through its prominence in Bordeaux wines, where it is often blended with Merlot and Cabernet Franc. From France and Spain, the grape spread across Europe and to the New World where it found new homes in places like California's Napa Valley, New Zealand's Hawke's Bay, South Africa's Stellenbosch region, Australia's Margaret River, McLaren Vale and Coonawarra regions, and Chile's Maipo Valley and Colchagua. For most of the 20th century, it was the world's most widely planted premium red wine grape until it was surpassed by Merlot in the 1990s. However, by 2015, Cabernet Sauvignon had once again become the most widely planted wine grape, with a total of 341,000 hectares (3,410 km2) under vine worldwide.
Rioja is a wine region in Spain, with denominación de origen calificada. Rioja wine is made from grapes grown in the autonomous communities of La Rioja and Navarre, and the Basque province of Álava. Rioja is further subdivided into three zones: Rioja Alta, Rioja Oriental and Rioja Alavesa. Many wines have traditionally blended fruit from all three regions, though there is a slow growth in single-zone wines.
Barolo is a red denominazione di origine controllata e garantita (DOCG) wine produced in the northern Italian region of Piedmont. It is made from the nebbiolo grape and is often described as one of Italy's greatest wines.
Winemaking, wine-making, 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. There is evidence that suggests that the earliest wine production took place in Georgia and Iran around 6000 to 5000 B.C. The science of wine and winemaking is known as oenology. A winemaker may also be called a vintner. The growing of grapes is viticulture and there are many varieties of grapes.
Barbera is a red Italian wine grape variety that, as of 2000, was the third most-planted red grape variety in Italy. It produces good yields and is known for deep color, full body, low tannins and high levels of acidity.
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, usually alcoholic beverages; a small barrel or cask is known as a keg.
Chablis is the northernmost Appellation d'origine contrôlée of the Burgundy region in France. Its cool climate produces wines with more acidity and less fruitiness than Chardonnay vines grown in warmer ones. These often have a "flinty" note, sometimes described as "goût de pierre à fusil", and sometimes as "steely". The Chablis AOC is required to use Chardonnay grapes solely.
A cooper is a craftsman who produces wooden casks, barrels, vats, buckets, tubs, troughs, and other similar containers from timber staves that were usually heated or steamed to make them pliable.
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 crushing the grapes to free the juice and pulp from the skin with yeast serving to convert sugar into ethanol. 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 wine is fruity with very low tannins. It is ready to drink quickly but lacks the structure for long-term aging. In extreme cases such as Beaujolais nouveau, the period between picking and bottling can be less than six weeks.
A rosé is a type of wine that incorporates some of the 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 skin contact method. The pink color can range from a pale "onionskin" orange to a vivid near-purple, depending on the grape varieties used and winemaking techniques. Usually, the wine is labelled rosé in French, Portuguese, and English-speaking countries, rosado in Spanish, or rosato in Italian.
Maury is an Appellation d'Origine Contrôlée (AOC) for fortified vin doux naturel wines made in the Roussillon wine region of France. Almost all wines are red, made from at least 75% Grenache noir (Garnacha). Other permitted grapes are Grenache blanc, Grenache gris, Macabeu (Macabeo), Malvoisie du Roussillon (Tourbat), Syrah, Muscat and other local varieties. Although the grapes are different, they are used and marketed very much like port. It is made in the communes of Maury, Saint-Paul-de-Fenouillet, Lesquerde, Tautavel and Rasiguères. The AOC was granted in 1936.
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. 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 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, red wine grapes are allowed some maceration between the skins and must, but not to the extent of red wine production.
Lees are deposits of dead yeast or residual yeast and other particles that precipitate, or are carried by the action of "fining", to the bottom of a vat of wine after fermentation and aging. The same while brewing beer at a brewery is known as trub – the same from secondary fermentation of wine and beer are the lees or equally, as to beer only, dregs. This material is the source for most commercial tartaric acid, which is used in cooking and in organic chemistry.
The process of fermentation in winemaking turns grape juice into an alcoholic beverage. During fermentation, yeasts transform sugars present in the juice into ethanol and carbon dioxide. In winemaking, the temperature and speed of fermentation are important considerations as well as the levels of oxygen present in the must at the start of the fermentation. The risk of stuck fermentation and the development of several wine faults can also occur during this stage, which can last anywhere from 5 to 14 days for primary fermentation and potentially another 5 to 10 days for a secondary fermentation. Fermentation may be done in stainless steel tanks, which is common with many white wines like Riesling, in an open wooden vat, inside a wine barrel and inside the wine bottle itself as in the production of many sparkling wines.
The use of wine tasting descriptors allows the taster to qualitatively relate the aromas and flavors that the taster experiences and can be used in assessing the overall quality of wine. Wine writers differentiate wine tasters from casual enthusiasts; tasters attempt to give an objective description of the wine's taste, casual enthusiasts appreciate wine but pause their examination sooner than tasters. The primary source of a person's ability to taste wine is derived from their olfactory senses. A taster's own personal experiences play a significant role in conceptualizing what they are tasting and attaching a description to that perception. The individual nature of tasting means that descriptors may be perceived differently among various tasters.
The acids in wine are an important component in both winemaking and the finished product of wine. They are present in both grapes and wine, having direct influences on the color, balance and taste of the wine as well as the growth and vitality of yeast during fermentation and protecting the wine from bacteria. The measure of the amount of acidity in wine is known as the “titratable acidity” or “total acidity”, which refers to the test that yields the total of all acids present, while strength of acidity is measured according to pH, with most wines having a pH between 2.9 and 3.9. Generally, the lower the pH, the higher the acidity in the wine. There is no direct connection between total acidity and pH. In wine tasting, the term “acidity” refers to the fresh, tart and sour attributes of the wine which are evaluated in relation to how well the acidity balances out the sweetness and bitter components of the wine such as tannins. Three primary acids are found in wine grapes: tartaric, malic, and citric acids. During the course of winemaking and in the finished wines, acetic, butyric, lactic, and succinic acids can play significant roles. Most of the acids involved with wine are fixed acids with the notable exception of acetic acid, mostly found in vinegar, which is volatile and can contribute to the wine fault known as volatile acidity. Sometimes, additional acids, such as ascorbic, sorbic and sulfurous acids, are used in winemaking.
The aging of wine is potentially able to improve the quality of wine. This distinguishes wine from most other consumable goods. While wine is perishable and capable of deteriorating, complex chemical reactions involving a wine's sugars, acids and phenolic compounds can alter the aroma, color, mouthfeel and taste of the wine in a way that may be more pleasing to the taster. The ability of a wine to age is influenced by many factors including grape variety, vintage, viticultural practices, wine region and winemaking style. The condition that the wine is kept in after bottling can also influence how well a wine ages and may require significant time and financial investment. The quality of an aged wine varies significantly bottle-by-bottle, depending on the conditions under which it was stored, and the condition of the bottle and cork, and thus it is said that rather than good old vintages, there are good old bottles. There is a significant mystique around the aging of wine, as its chemistry was not understood for a long time, and old wines are often sold for extraordinary prices. However, the vast majority of wine is not aged, and even wine that is aged is rarely aged for long; it is estimated that 90% of wine is meant to be consumed within a year of production, and 99% of wine within 5 years.
This glossary of winemaking terms lists some of terms and definitions involved in making wine, fruit wine, and mead.
The role of yeast in winemaking is the most important element that distinguishes wine from fruit juice. In the absence of oxygen, yeast converts the sugars of the fruit into alcohol and carbon dioxide through the process of fermentation. The more sugars in the grapes, the higher the potential alcohol level of the wine if the yeast are allowed to carry out fermentation to dryness. Sometimes winemakers will stop fermentation early in order to leave some residual sugars and sweetness in the wine such as with dessert wines. This can be achieved by dropping fermentation temperatures to the point where the yeast are inactive, sterile filtering the wine to remove the yeast or fortification with brandy or neutral spirits to kill off the yeast cells. If fermentation is unintentionally stopped, such as when the yeasts become exhausted of available nutrients and the wine has not yet reached dryness, this is considered a stuck fermentation.
A barrel-aged beer is a beer that has been aged for a period of time in a wooden barrel. Typically, these barrels once housed bourbon, whisky, wine, or, to a lesser extent, brandy, sherry, or port. There is a particular tradition of barrel ageing beer in Belgium, notably of lambic beers. The first bourbon barrel-aged beers were produced in the United States in the early 1990s.
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