The History of OAK Barrels and Wine
The oak wine barrel is one of the most recognizable symbols associated with wine. We have romanticized the barrel and the act of aging wine inside of it to such a degree, that after the barrels have been used for their intended purpose we often turn them into tables, benches, planters and even candle holders. Yet the reason we began aging wine in oak barrels in the first place was not intentional, but the result of a happy accident. For millennia, the clay amphora was the storage medium of choice for transporting wine
The practice of using amphorae continued in the Greek and then the Roman Empire. As the Romans pushed north into Europe, and away from the Mediterranean, transporting the clay amphorae grew increasingly difficult. While the Romans were aware of palm wood barrels, the price and difficulty of bending the wood made them a poor choice. When the Romans encountered the Gauls, they found a group of people who were using wooden barrels, often made of oak, to transport beer.
The Romans quickly realized they had found a solution to their amphora issue. While other woods were used, oak was popular for a number of reasons. First, the wood was much softer and easier to bend into the traditional barrel shape than palm wood, thus the oak only needed minimal toasting and a barrel could be created much faster. Second, oak was abundant in the forests of continental Europe. And finally, oak, with its tight grain, offered a waterproof storage medium. The transition to wooden barrels was swift. In less than two centuries, tens of millions of amphorae were discarded.
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.
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.
Where OAK comes from
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.
Parts of an Oak Barrel
Charring Oak Barrels
Last time we looked at the differences between new oak versus neutral oak wine barrels. New oak imparts lots of flavors to wine. But after about three vintages, the oak no longer imparts flavor so it is
called neutral oak.
Much of the flavor imparted by the oak occurs naturally from the raw wood. But winemakers learned long ago that by “toasting” the inside of an oak barrel, they can enhance these flavors.
After a barrel is built, its inside can be exposed to fire to “toast” it. This is done either over an open flame or using a hand-held torch. The fire ‘caramelizes’ the wood’s natural sugars and brings out complex compounds. From this, the wine will ultimately take on flavors that are toasty, charred, spicy and sweet depending on the amount of time the wood is toasted.
A lightly toasted barrel spends about 25 minutes exposed to flame while a heavily toasted barrel may get up to one hour of flame exposure.
Essentially, the heavier the toast, the stronger and more varied are the imparted flavors:
Light Toasting – Vanilla, coconut, caramel, clove and cinnamon
Medium Toasting – Vanilla, honey, caramel, toast, coffee, cocoa
Heavy Toasting – Vanilla, espresso, smoke, crème brûlée, butterscotch, toffee, molasse
Major areas will top Oak is harvested and made into wine barrels
France
In France, both the Quercus robur (common oak) and Quercus petraea (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 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]
Hungary
The trees in the Hungarian Zemplén
Mountains grow slower in the volcanic soil and smaller, 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 slower than American or French oak.
United States
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.
The major differences between various oak
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.[8] 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.
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.
Not just wine
Bourbon and Tennessee whiskeys are aged in American Oak. Scotch whiskey
is normally aged in European Oak.
These barrels are either toasted (Europe)
or charred (USA)
Toasting both mellows the tannins in the wood, as well as changes the flavors the barrel might impart from raw wood to more spicy, vanilla notes—toasting actually helps release vanillin from the cellulose in the wood. There are varying degrees of toasting—from a light toast to a heavy toast and, as you might imagine, that changes the way they can influence a wine. Essentially, the heavier the toast, the stronger the barrel’s flavors..
The word “Charred” implies that something has gone past toasting to partially burning, and indeed charred barrels look black inside—they are about an eighth of an inch charred. Charred barrels aren’t really used for wine, but they are a part of bourbon production. That charred wood ends up becoming a sort of activated carbon filter, which can help remove sulfur compounds from a whisky, and make a smoother drink. Charred barrels also impart a darker color, smoky notes as well as caramel, honey and plenty of spicy accents.
Beer aged in Oak Barrels
From imperial stouts to lagers, almost every beer style on Earth is now being aged in wood. 
So many craft brewers are using old whiskey barrels (and rum barrels and tequila barrels and wine barrels) to add layers of nuance to their brews.
Fun things to do with small oak barrels
The standard size of a wine oak barrel can cost up to $2,500 So, that may not be feasible for everyday usage for people. But there are different sizes that can be used by anyone for more exciting beverages. 
One of the easiest is
to make your whiskey based cocktails. Making a bourbon or rye Manhattan and storing it in one of those small oak barrels will give you an extra and pleasing flavor
You can also try making your own vinegar. Starting with the vinegar “mother” adding wine or other ingredients you can make your own delicious wine vinegar and more complex balsamic vinegar.
The beauty of Wine Barrels in Caves
- Majority of the details contained in these post comes from Wikipedia