The use of oak in wine plays a significant role in winemaking and can have a profound effect on the resulting wine, impacting the color, flavor, tannin profile and texture of the wine. The term oak can be used as part of the common name of any of about 400 species of Trees and Shrubs in the Genus Quercus (from Latin Wine is an Alcoholic beverage made from the fermentation of Grape juice Winemaking, or vinification, is the production of Wine, starting with selection of the Grapes and ending with bottling the finished wine Tannins are Astringent, bitter plant Polyphenols that either bind and Precipitate or shrink Proteins The astringency from the tannins is what Oak can come into contact with wine in the form of a barrel during the fermentation or aging periods. The process of fermentation in Wine is the Catalyst function that turns Grape juice into an Alcoholic beverage. An aging barrel is a barrel used to age Wine or distilled spirits such as Whiskey, Brandy, or Rum. It can be introduced to the wine in the form of free floating oak chips or as wood staves (or sticks) added to wine in a fermentation vessel like stainless steel. Oak introduced in the form of a wine barrel can impart other qualities to the wine through the process of evaporation and low level exposure to oxygen. Evaporation is the process by which Molecules in a Liquid state (e Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the [1]
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History
In early wine history the amphora was the vessel of choice for the storage and transportation of wine. The history of Wine spans thousands of years and is closely intertwined with the history of Agriculture, Cuisine, Civilization and An amphora (plural amphorae or amphoras) is a type of Ceramic Vase with two handles and a long neck narrower than the body 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. Herodotus of Halicarnassus ( Greek: Hēródotos Halikarnāsseús) was a Greek Historian who lived in the 5th century BC ( 484 BC&ndash Mesopotamia (from the Greek meaning "land between the rivers" is an area geographically located between the Tigris and Euphrates rivers largely corresponding Arecaceae or Palmae (also known by the name Palmaceae, which is taxonomically invalid or commonly palm tree) the palm family is a family of Flowering The Euphrates ( ( Arabic: ar نهر الفرات; Turkish: tr Fırat Syriac: syr ܦܪܬ; Hebrew: he פרת 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 Roman empire. A millennium (pl millennia) is a period of Time equal to one thousand Years (from Latin la mille, thousand and la annum The Roman Empire was the post-Republican phase of the ancient Roman civilization, characterised by an autocratic form of government and large territorial In time, winemakers discovered that beyond just storage convenience that wine kept in oak barrels took on properties that improved the wine by making it softer and in some cases better-tasting. [3] Robert Mondavi is credited with expanding the knowledge of winemakers in the United States about the different types of oak and barrel styles through his experimentation in the 1960s & 1970s. Robert Gerald Mondavi ( June 18, 1913 – May 16, 2008) was a leading American Vineyard operator whose technical improvements The United States of America —commonly referred to as the [4]
Effects on wine
The porous nature of an oak barrel allows some levels of evaporation and oxygenation to occur in wine but typically not at levels that would cause oxidation or spoilage of the wine. Oxygenation refers to the amount of Oxygen in a medium In Blood it may be taken to be synonymous with Saturation, which describes the degree to which Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state A wine fault or defect is an unpleasant characteristic of a Wine often resulting from poor Winemaking practices In a year, the typical 59 gallon barrel can lose anywhere from 5 1/2 to 6 1/2 gallons of wine through the course of evaporation. A gallon is a measure of Volume. It is in current use in the United States and still has limited use in many other English-speaking countries This evaporation (of mostly alcohol and water) allows the wine to concentrate its flavor and aroma compounds. Water is a common Chemical substance that is essential for the survival of all known forms of Life. Flavor or flavour is the sensory impression of a Food or other substance, and is determined Small amounts of oxygen are allowed to pass through the barrel and acts as a softening agent upon the tannins of the wine. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Tannins are Astringent, bitter plant Polyphenols that either bind and Precipitate or shrink Proteins The astringency from the tannins is what [3]
The chemical properties of oak itself can have a profound effect on the wine. Phenols within the wood interact with the wine to produce vanilla type flavors and can give the impression of tea notes or sweetness. In Organic chemistry, phenols, sometimes called phenolics, are a class of Chemical compounds consisting of a Hydroxyl group (- Vanilla is a Flavoring derived from Orchids of the genus Vanilla native to Mexico. The degree of "toast" on the barrel can also impart different properties affecting the tannin levels of the wine as well as the aggressive wood flavors. [5] The hydrolyzable tannins present in wood, known as ellagitannins, are derived from lignin structures in the wood. Hydrolysis is a Chemical reaction during which one or more water molecules are split into hydrogen and hydroxide ions which may go on to participate in further reactions Lignin or lignen is a complex Chemical compound most commonly derived from Wood and an integral part of the secondary Cell walls of Plants They help protect the wine from oxidation and reduction. [6]
Wines can be barrel fermented in oak or they can be placed in oak after fermentation for a period of aging or maturation. The process of fermentation in Wine is the Catalyst function that turns Grape juice into an Alcoholic beverage. Wine that is matured in oak receive more of the oak flavors and properties than wine that is fermented in oak. This is because yeast cells interact with and "latch on" to the oak components. Yeasts are a growth form of eukaryotic Microorganisms classified in the kingdom Fungi, with about 1500 Species currently described When the dead yeast cells are removed from the wine as lees some of these oak properties go with them. Lees refers to deposits of dead Yeast or residual yeast and other particles that precipitate or are carried by the action of " Fining " to the bottom of [7] A characteristic of white wines that are fermented in oak include a pale color with an extra silky texture. White wines that are fermented in steel and then matured in oak will have a darker coloring due to the heavy phenolic compounds that are still present. [8] Flavor notes that are common descriptions of wines exposed to oak include caramel, cream, smoke, spice and vanilla. Caramel (pronounced /ˈkærəmɛl/ or /ˈkɑrməl/ refers to a range of confections that are Beige to dark brown in Color, derived from the For the 1993 hip-hop single by the Wu-Tang Clan see CREAM CREAM is an acronym for Cognitive Reliability Error Analysis Method a Smoke is the collection of airborne solid and liquid Particulates and Gases ref> ''Smoke Production and Properties'' - SFPE Handbook of Fire Protection Engineering A spice is a dried Seed, Fruit, Root, Bark or vegetative substance used in Nutritionally insignificant quantities as a Food additive Chardonnay is a variety that has very distinct flavor profiles when fermented in oak that include coconut, cinnamon and cloves notes. Chardonnay is a green-skinned Grape variety used to make white Wine. The Coconut Palm ( Cocos nucifera) is a member of the Family Arecaceae (palm family Cinnamon ( Cinnamomum verum, synonym C zeylanicum) is a small Evergreen Tree 10–15 metres (32 This article is about the Spice; for other meanings see Clove (disambiguation. The "toastiness" of the barrel can bring out varying degrees of mocha and toffee notes in red wine. Toffee is a Confection made by boiling Molasses or Sugar (creating inverted sugar) along with Butter, and occasionally Flour [9]
The length of time that a wine spends in the barrel is dependent on the varietal and style of wine that the winemaker wishes to make. Varietal describes Wines made primarily from a single named Grape variety. The majority of oak flavoring is imparted in the first few months that the wine is in contact with oak but a longer term exposure can effect the wine through the light aeration that the barrel allows which helps to precipitate the phenolic compounds and quickens the aging process of the wine. Aeration is the Process by which Air is circulated through mixed with or dissolved in a Liquid or substance [8] New World Pinot noir may spend less then a year in oak. New World wines are those Wines produced outside the traditional wine-growing areas of Europe, in particular from Argentina, Australia, Canada Pinot noir ('pino nwar is a red Wine Grape variety of the species Vitis vinifera. Premium Cabernet Sauvignon maybe spend two years. Cabernet Sauvignon is one of the world's most widely recognized red Wine grape varieties. The very tannic Nebbiolo grape may spend four or more years in oak. The Nebbiolo ( Italian) or Nebieul ( Piedmontese) is one of the most important wine Grape varieties of Italy 's Piedmont High end Rioja producers will sometimes age their wines up to ten years in American oak to get a desired earthy, vanilla character. Rioja is a Wine, with Denominación de Origen Calificada (DOC [7]
Oak types and sources
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. The tree species Quercus alba, also called "white oak" is one of the pre-eminent hardwoods of eastern North America It is found in most of the Eastern United States as well as Missouri, Minnesota and Wisconsin where many wine barrels are from. The Eastern Half of The United States, the American East, or simply the East is traditionally defined as the states east of the Mississippi River. Missouri ( or) is a state in the Midwestern region of the United States bordered by Iowa, Illinois, Kentucky, Tennessee Minnesota ( Native Americans demonstrated the name to early settlers Wisconsin ( or wɪˈskɑnsɨn (French Ouisconsin) is one of the fifty United States of America, located in the north central part of the United States In Oregon the Quercus garryana white oak has started to gain usage due to its closer similarities to European oak. Oregon ( is a state in the Pacific Northwest region of the United States. The Garry Oak ( Quercus garryana) also known as Oregon White Oak or Oregon Oak, has a range from southern California to extreme southwestern In France, the main winemaking oak species is the Quercus petraea which is known for tighter grain, high tannins and lower aromatics then its American oak counterpart. The Sessile Oak ( Quercus petraea, or Quercus sessiliflora) also known as Durmast Oak, is a species of Oak native to most of Europe French oak typically comes from one or more primary forests: Allier, Limousin, Nevers, Troncais and Vosges. Allier ( Occitan: Alèir) is a department in south-central France named after the Allier River. Limousin ( Occitan: Lemosin) is one of the 26 regions of France. Nevers ( Latin: Noviodunum, later Nevirnum and Nebirnum) is a commune of central France, the Préfecture Vosges (voːʒ is a French department, named after the Vosges mountain range. The wood from each of these forests has slightly different characteristics. Many winemakers utilize barrels made from different cooperage, regions and degrees of toasting in blending their wines to enhance the complexity of the resulting wine. [10]
Italian winemakers have had a long history of using Slovenian oak from the Quercus robur which is known for its tight grain, low aromatics and medium level tannins. Italian wine is Wine produced in Italy, a Country which is home to some of the oldest wine-producing regions in the world Slovenia, officially the Republic of Slovenia (Republika Slovenija) is a Country in southern Central Europe bordering Italy to the west Quercus robur (sometimes considered Q pedunculata) is commonly known as the pedunculate oak or English oak. Prior to the Russian Revolution, Quercus petraea oak from the Baltic states was the most highly sought after wood for French winemaking. See also Russian Revolution (1905 The Russian Revolution of 1916 refers to a series of popular revolutions in Russia, and the events surrounding them The Baltic states (Balti riigid Baltijas valstis Baltijos valstybės or Baltic countries are three countries in Northern Europe, all members of the French wine is produced in several regions throughout France, on over 800000 Hectares (over 2 million Acres of Vineyards and in a typical [11] Today Russian oak from the Adygey region along the Black Sea is being explored by French winemakers as a cheaper alternative to French oak. The Black Sea is an inland Sea bounded by southeastern Europe, the Caucasus and the Anatolian peninsula ( Turkey [12] Canadian wineries have been experimenting with the use of Canadian oak, which proponent describe as a middle ground between American and French oak even though it is the same species as American oak. Canadian wine is produced in Southern Ontario and southern British Columbia, and Nova Scotia. [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 59 gallon barrels. The trees are typically harvested in the winter months when there is less sap in the trunk. In Agriculture, the harvest is the process of Gathering mature crops from the fields Reaping is the cutting of Grain [11]
Differences in French and American oak
American oak tends to be more intensely flavored then French oak with more sweet and vanilla overtones due to the American oak having two to four times as many lactones. lactone is a cyclic Ester in Organic chemistry. It is the condensation product of an Alcohol group and a Carboxylic acid [9] Winemakers that prefer American oak typically use them for bold, powerful reds or warm climate Chardonnays. Chardonnay is a green-skinned Grape variety used to make white Wine. Besides being derived from different species, a major difference between American and French comes from the preparation of the oak. The tighter grain and less watertight nature of French oak encourages coopers to split the wood along the grain rather than saw. Traditionally a cooper is someone who makes Wooden staved vessels of a conical form of greater length than breadth bound French oak is then traditionally aged or "seasoned" for at least two years whereas American coopers will often use a kiln-dry method to season the wood. Kilns are thermally insulated chambers or Ovens in which controlled temperature regimes are produced [11] Long periods of outdoor season has a mellowing effect on the oak that kiln-dry methods have difficulties replicating. [9] The sawing, rather than splitting, of American oak also enhances the differences between the two styles due to the rupture of the xylem cells in the wood which releases many of the vanillin aromatics and lactones responsible for characteristics like the coconut notes. In Vascular plants xylem is one of the two types of transport tissue Phloem being the other Vanillin, methyl vanillin, or 4-hydroxy-3-methoxybenzaldehyde, is an Organic compound with the molecular formula C8H8O3 [14]
Wine barrel
- See also: Aging barrel
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, butter and spice flavors to wine. The size of the barrel plays a large role in determining the effects use 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 barriques style which hold 59 gallons (225 liters) followed by the Burgundy style barrel which hold 60 gallons (228 liters). Some New World wine makers use the large hogshead 79 gallon (300 liter) size. A hogshead is a large cask of liquid (less often of a food commodity) [8]
New barrels impart more flavors than do previously used barrels. Over time many of the oak properties get "leeched" 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. Vintage, in Wine -making is the process of picking Grapes and creating the finished product [5] The cost of barrels varies due to the supply and demand market economy and can change with different features that a cooperage may offer. Supply and demand is an Economic model describing effects on price and quantity in a Market. As of late 2007 the price for a standard American oak barrel was $270 USD, French oak $600 USD, and Eastern European $480 USD. The United States dollar ( sign: $; code: USD) is the unit of Currency of the United States; it has also been [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]
Barrel construction
Barrels are constructed in cooperages with wood that is purchased at auction houses. Traditionally a cooper is someone who makes Wooden staved vessels of a conical form of greater length than breadth bound The traditional method of European coopers have 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 leeched 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. Kilns are thermally insulated chambers or Ovens in which controlled temperature regimes are produced While this method is much faster, it doesn't 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 shape of the desired barrel and held together with iron rings. SpecialShortpages.-- 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. Burgundy wine ( is wine made in the Burgundy region in eastern France. [8] 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. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 During the process of toasting, the furanic aldehydes in the wood reach a higher level of concentration. Furan, also known as furane and furfuran, is a heterocyclic Organic compound. An aldehyde is an organic compound containing a terminal Carbonyl group. 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. Eugenol (C10H12O2 is an allyl chain-substituted Guaiacol. Eugenol is a member of the Phenylpropanoids class of chemical compounds Oil of cloves, also known as Clove oil, is an Essential oil from the Clove plant Syzygium aromaticum. [14]
Barrel alternatives
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 butter and vanilla flavors. A barrel or cask is a hollow cylindrical container traditionally made of Wood Staves and bound with Iron Hoops The Winemaking, or vinification, is the production of Wine, starting with selection of the Grapes and ending with bottling the finished wine A winery is a building or property that produces Wine, or a business involved in the production of wine such as a wine company. 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. For other uses of the word staff see Staff. A staff is a large thick Stick or stick-shaped object used to help with Walking Wines made from these barrel alternatives typically do not age as well as wines that are matured in barrels. [8] Improvements in micro-oxygenation has allowed winemakers to better mimic the gentle aeration of oak barrels in stainless steel tanks with oak chips. Micro-oxygenation is a process used in Winemaking to introduce Oxygen into wine in a controlled manner [18]
Prior to 2006, the practice of using oak chips was outlawed in the European Union. The European Union ( EU) is a political and economic union of twenty-seven member states, located primarily in [19] In 1999, the Bordeaux court of appeals fined four chateaus, including third growth Chateau Giscours, more the $13,000 USD for the use of oak chips in their wine. Château Giscours is a Winery in the Margaux appellation of the Bordeaux region of France, in the commune of Labarde. [20]
Other wood types
Throughout history other wood types, including chestnut, pine, redwood, and acacia, have been used in crafting winemaking vessels, particular large fermentation vats. Chestnut ( Castanea) (including some chinkapin or Chinquapin) is a Genus of eight or nine Species of Deciduous This article is about the tree For other uses of the term "pine" see Pine (disambiguation. Acacia is a Genus of Shrubs and Trees belonging to the Subfamily Mimosoideae of the family Fabaceae, first However none of these wood types possess the compatibility with wine that oak has demonstrated in combining it 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. [21] 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. In chemistry paraffin is the common name for the Alkane Hydrocarbons with the general formula C n H2 n +2 Redwood is too rigid to bend into the smaller barrel shapes and imparts an unpleasant flavor. Acacia imparts a yellow tint to the wine. Other hardwoods like apple and cherry wood have an off putting smell. The apple is the pomaceous Fruit of the apple tree Species Malus domestica in the Rose family Rosaceae. This article is about the Cherry berry also classified as fruit for the ornamental tree See Cherry Blossom. [22] Austrian winemakers have a history of using Acacia barrels. Austrian wines are mostly dry White wines (often made from the Grüner Veltliner grape with some luscious Dessert wines made around the Neusiedler Historically, chestnut was used by Beaujolais, Italian and Portuguese wine makers. Beaujolais is a French Appellation d'Origine Contrôlée (AOC Wine generally made of the Gamay Grape which has a thin Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest Portuguese wine is part of the ancient traditions introduced to the region by ancient civilizations such as the Phoenicians Carthaginians Greeks, and mostly [23] 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. The Rhône wine region in Southern France is situated in the Rhône river valley and produces numerous wines under various Appellation d'origine contrôlée In Chile there are traditions for using barrel made of rauli wood but it is beginning to fall out of favor due to the musky scent it imparts on wine. Chilean wine is Wine made in the South American country of Chile. UserPolbot. --> Nothofagus alpina (syn N procera) (Rauli is a species of Plant in the Fagaceae [24]
References
- ^ J. Robinson Jancis Robinson's Wine Course Third Edition pg 91-93 Abbeville Press 2003 ISBN 0789208830
- ^ H. Johnson Vintage: The Story of Wine pg 25-26 Simon and Schuster 1989 ISBN 0671687026
- ^ a b K. MacNeil The Wine Bible pg 40 Workman Publishing 2001 ISBN 1563054345
- ^ H. Johnson Vintage: The Story of Wine pg 453 Simon and Schuster 1989 ISBN 0671687026
- ^ a b K. MacNeil The Wine Bible pg 41 Workman Publishing 2001 ISBN 1563054345
- ^ J. Robinson (ed) "The Oxford Companion to Wine" Third Edition pg 492 Oxford University Press 2006 ISBN 0198609906
- ^ a b K. MacNeil The Wine Bible pg 45 Workman Publishing 2001 ISBN 1563054345
- ^ a b c d e J. Robinson Jancis Robinson's Wine Course Third Edition pg 93 Abbeville Press 2003 ISBN 0789208830
- ^ a b c D. Sogg "White Wines, New Barrels: The taste of new oak gains favor worldwide" Wine Spectator July 31st, 2001
- ^ T. Stevenson "The Sotheby's Wine Encyclopedia" pg 33-34 Dorling Kindersley 2005 ISBN 0756613248
- ^ a b c J. Robinson Jancis Robinson's Wine Course Third Edition pg 92 Abbeville Press 2003 ISBN 0789208830
- ^ D. Sogg "French Barrelmaker Turns to Russian Oak" Wine Spectator Oct. 15th 2002
- ^ K. Ebjich "Canadian Oak Barrels Get the Nod From Winemakers" Wine Spectator Nov. 11th 2003
- ^ a b T. Stevenson "The Sotheby's Wine Encyclopedia" pg 33 Dorling Kindersley 2005 ISBN 0756613248
- ^ World Cooperage Product Information
- ^ a b D. Sogg "Oak Flavorings" Wine Spectator Sept. 20th, 2002
- ^ a b K. MacNeil The Wine Bible pg 42-43 Workman Publishing 2001 ISBN 1563054345
- ^ J. Robinson (ed) "The Oxford Companion to Wine" Third Edition pg 491 Oxford University Press 2006 ISBN 0198609906
- ^ Jancis Robinson (May 4, 2006). Events 1256 - The Augustinian monastic order is constituted at the Lecceto Monastery when Pope Alexander IV Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Giant 'teabags' of oak chips now legal in Europe. San Francisco Chronicle.
- ^ J. Mann "Bordeaux Chateaus Fined for Use of Wood Chips" Wine Spectator Nov 29th, 1999
- ^ J. Robinson Jancis Robinson's Wine Course Third Edition pg 91 Abbeville Press 2003 ISBN 0789208830
- ^ J. Ross "Rethinking American vs. French oak" Wines & Vines November 1st, 1992
- ^ J. Robinson (ed) "The Oxford Companion to Wine" Third Edition pg 775 Oxford University Press 2006 ISBN 0198609906
- ^ T. Stevenson "The Sotheby's Wine Encyclopedia" pg 32 Dorling Kindersley 2005 ISBN 0756613248
External links
Further reading
Gawel, Richard. Oak barrel alternatives in winemaking. Wine Tutor, August 2002 (available at [1])
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