Winemaking: Oak Barrels

Oak is the common name for over 300 species of trees belonging to the genus Quercus. Of the many species, only a few are suitable as cooperage for the simple reason they must be non-porous (i.e. not leak). White oak has blockages (tyloses) in its xylem system, the capillary tubes which move liquids from the roots to the leaves. The most common oaks of Europe are Quercus sessilis and Q. robur. In the United States, the predominant species is Q. alba.

oak-barrelsBarrels made from American white oak were originally produced for the bourbon industry. However, American oak barrels are increasingly being used by wineries, particularly given recent improvements in barrel fabrication and simple economics (top quality American oak barrels cost $350 to $500 while their French counterparts cost between $900 – $1,200).

American oak barrels have improved dramatically since about 1995. Until recently, no effort was made to identify American white oak (Q. alba) by its specific area of origin. A guess could be made of the provenance by identifying the mills at which the oak was cut. A few coopers are currently offering Q. alba barrels from oaks grown in specific areas of the eastern U.S. and the Great Lakes area, while other coopers prefer to focus on grain tightness as the most important factor in determining flavor contributions.

Oak hybridizes naturally, and at last count there are at least 400 hybrids. Because of this, there is uncertainty among botanists as to oak identification in France. For this reason, oak from France is carefully identified by its region of origin, even though the species may be the same. Most of the forests of France (approximately 80%) are owned by the French government, and are managed by the Office National de Forêts, established by Napoleon II. All trees are sold by auction, prior to being cut. Oak trees for cooperage purposes are harvested when they are between 110-150 years old.

Oak origin flavor characteristics

  • Limousin (LIH-moo-sahn) perfumes wine quickly and can add a yellow-gold color. Limousin is aggressive and one-dimensional, adding a vanillin note. Limousin comes from a French province just north of Bordeaux. The open grain of the wood results from shallow rooting conditions and a lot of rain. Limousin is used extensively for the maturation of Cognac.
  • Nevers (neh-VEHR) contributes a baking spice, cinnamon-like flavor. It is initially aggressive in tannin. Nevers comes from several forests in the center of France. The region is gently rolling and the soils are rich and moist. The trees grow tall and straight in forest conditions, which produces logs that are generally medium-tight grain.
  • Allier (ah-leh-YAY) oak comes from a forest immediately south of Nevers, and is similar although more tightly grained. Allier releases its perfume slowly with finesse, and seems to be spicier.
  • Vosges (VOH-zh) oak comes from a low mountain region in the northeast corner of France. Vosges offers a subtle vanillin nose much beloved by makers of fruity wine. Vosges has soft texture on the palate.
  • Tronçais (tron-SAY) oak comes from a specific forest within the Allier Département. It was deliberately planted for the ship building trade in the late 17th century. The forest grows in deep, fertile soils producing trees of great size with a very fine grain. Demand makes Troncais expensive. It is the tightest grained French oak, and flavors wines the most slowly.
  • American white oak is more strongly scented and obvious than French oak. Descriptions range from dill to coconut oil. The most recognizable description is Bourbon-like (Bourbon wouldn’t have a smell were it not for American oak). The smell has a sweetness. American oak is very tightly grained.

For this information on barrels, we are considerably indebted to Mel Knox, barrel broker extraordinaire.

 

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