boisé is a legal additive utilized in aged spirit production which can intensify or mimic the character of barrel aging; it is made by boiling down oak chips in water into a thick, woody brown liquid that can be then mixed with eau-de-vie and liquid sugar. As a traditional and common component of many brandies, it is legally controlled and defined by French law for use in all French brandies. Though a “liquid oak extract” called boisé is reported as having been “invented” (undoubtedly patented) by Antoine Descoffre in 1902 in the Poitou-Charentes (Cognac) region, oak maturation is such an integral part of brandy manufacture that it is difficult to fix starting lines for boisé and similar treatments.
Brandy is by French law a grape-based spirit that has been aged and matured in oak barrels. See élevage and maturation. In the case of cognac, Armagnac, and calvados the shape, size, origin, and manufacture of those barrels is at least partly defined by law, as is the maturation of each. See barrel. But time is money. Boisé exists to enhance brandy aroma and flavor and to accelerate the aging process. Unsurprisingly, discussion around boisé is charged, as some consider it useful and even essential and others believe it is somehow dishonest.
One cognac house has been accused of “tampering” with their cognac by soaking oak chips in brandy in a stainless steel vat instead of extracting oak chips with a water solution. This is by no means uncommon, but the rules since 1921 (and re-established in 1990) are such that a gentle water extraction is legal while a more robust alcohol or brandy extraction is not. Most use hot or nearly boiling water; some use an ambient temperature. The defendants have maintained that an alcohol or brandy extraction of oak chips is historical; it is also allowed by EU rules. The matter is not settled. See oak chips.
But the use of boisé remains widespread, while candor is not. Consider that Cognac and other brandies require amelioration with water: these “petits eaux” are sometimes themselves aged in barrel, extracting oak character, albeit gently. It is no great leap to allowing oak pieces to be in the barrel too; records suggest such practices go back more than a century and a half. Like other such activities, secrecy has given the air of deceit to the use of “oak additives.” But the aromas are hardly foul; the characteristics of vanilla, caramel, butterscotch, clove, allspice, and all the other myriad smells of traditional oak aging can be mirrored by boisé.
The counterargument is that boisé can only duplicate raw oak aromas and is unable to offer the oxidative process that exemplifies oak aging. So far, data suggest only partial support for this view: true rancio is not wholly duplicated by boisé, but many of its constituent elements are. See rancio.
Wood chips, inner staves (new staves inside older barrels), and wood powder are commonly used in wine production in the New and Old Worlds. Likewise, such tools have been in the brandy maker’s kit bag for as long as records have been kept and likely before. According to some, wood chips are more recent innovations (though the 1921 regulations speak directly to their use or misuse), while inner staves date back to the mid-nineteenth century and “are quite mastered.” These are toasted to the same specifications as the barrel staves themselves, and serve to “refresh” any used and depleted barrel.
Today, many micro-distillers use wood infusions created by pressure-cooking wood chips in spirit; this is fairly described by traditional producers as heavy-handed and creates a new kind of boisé of excess bitterness and imbalance.
Faith, Nicholas. Cognac: The Story of the World’s Greatest Brandy. Oxford: Infinite Ideas, 2013.
“The State-of-the-Art Estate Winery.” Vinovation, http://www.vinovation.com/equipment.htm (accessed April 18, 2016).
By: Doug Frost