Bourbon Barrel And Its Influence On Aging – Part One

bourbon Barrel Aging WhiskeyAlthough aging alcohol in oak has a long history, managing the wood used for aging is a discipline that is much newer.  Early producers appreciated the benefits of an oak bourbon barrel for years before they began to gain the technical knowledge needed to understand the benefits of an oak bourbon barrel beyond the anecdotal theory.  With the advances of analytical techniques that now reveal the types of influence bourbon barrels have on the maturation of the bourbon along with the increased focus on malts and longer maturation terms wood management for the bourbon barrel has grown in importance.  The mandate of the distiller is to reach a balance between the good characteristics offered by the oak while developing and retaining an individual character of the particular distiller in order that will be embodied in new make spirit.  As bourbon barrel aging accounts for as much as 70% of The eventual flavor of the malt or about 40% in the event of heavy peating, the distiller must take part in this balancing act.  As different malts have different potential benefits of aging, increasing the maturation is no guarantee of creating the finest malts.  It is a case of variations on the theme:  different ages in the bourbon barrel yield different expressions as the flavor of the oak increases.  In addition, the appeal of the malt is sometime more is more while other times less as more according to the particular spirit and consumer.  The right time in the bourbon barrel may be dependant on one’s own palate.

Younger whiskey often has a great enthusiasm, but after about ten years in a bourbon barrel begins to develop a mellowing out and a better balance.  Some find that balance after 15-20 years in the bourbon barrel.  At 20 years, the oak in a bourbon barrel begins to show more influence and after 25 years in a bourbon barrel, the product has a rounder, mellower, drier character where the heat is felt in the chest instead of the palate.  At somewhere between 25 and 30 years in the bourbon barrel, the malt is matured and begins to play an important role.  Beyond 30 years in the bourbon barrel the concentration of oak in the spirit is significant.

The maturation process in the bourbon barrel takes three essential steps.  Subtractive maturation, serves as a rite of passage where the spirit in the bourbon barrel loses its immaturity.  Additive maturation provides color, flavor and aroma from the bourbon barrel.  Interactive maturation includes reactions between the spirit and the bourbon barrel.  This is a type of mystical union, not yet fully understood, but yielding additional characteristics not found in either the bourbon barrel oak or the spirit individually.

While a simplistic way of looking at this maturation process that occurs in a bourbon barrel is in an ordered, chronological sequence, each of the separate elements occur during maturation simultaneously throughout the process, although they happen at different rates in the bourbon barrel.

Bourbon barrel spirits from oak are evident within the barrel beginning around six months while the loss of immaturity may take two or more years in the bourbon barrel.  In addition, filling the barrel with the spirit begins the interactive maturation.  During this process, the staves absorb 2-3% of the spirit in as little as 48 hours, allowing it to mingle with the wood of the bourbon barrel and extract the previous contents of the bourbon barrel.  The full effect takes years to complete.  In fact specific flavors are attributed to the interactive maturation of the spirit and bourbon barrel in the formation of esters.

Although the MacAllan’s citrus and the floral notes are from the new make spirit, the notes of dried fruits are from extracts created as alcohol interacts with the bourbon barrel along with oxidation, according the MacAllan’s Master Distiller David Robinson.  One of the considerations is the difference in choosing a bourbon barrel made of American oak and a sherry cask normally created using European oak, although one will see American Oak bourbon barrels being used in some sherry bodegas.

European oak is typically harvested from trees that range from 60-15o years and offers a more porous and open grain when compared to American oak.  As a result, the spirit penetrates deeper into the oak, more readily than with Bourbon barrels made of American oak that is harvested in the 40-100 year range to create a tighter grained product.  European oak also offers a higher level of tannins than found in American oak.  However; bourbon barrels are charred inside while the European product is merely toasted, making the American bourbon barrel more accessible to the spirit being aged inside.

Such technical differences also make a difference in several ranges of characteristics.  With color coordination, the sherry cask creates an amber to orange which is very distinct from the lighter straw to golden tent imparted by a bourbon profile.  In addition, the sherry cask imparts rich fruit flavor, akin to prunes, raisins, dates, apricots or figs, along with hints of almond, walnut and spices.  The cask adds a chocolate, cream caramel and even a positive sulfurous note to the rich sweetness.

On the other hand bourbon barrels create a drier, lighter sweetness that creates a medley of flavors, such as honey, vanilla, fruits, hazelnuts, almonds, coconut, sherbet, crème brulee, spices as well as notes of eucalyptus and mint.

Bourbon Barrel And Its Influence On Aging – Part Two