Barrel aging beers in previously used casks results in an incredibly complex array of flavors being imparted to the beer. Traditionally Brewers have focused on barrel aging in Bourbon casks but the team at Marshall Wharf wanted to add another layer of complexity….aging in Scotch Whisky casks…nothing new in Europe but something very new for a small craft brewer in Maine.
Understanding maturation of Marshall Wharf beers in the Bowmore casks requires a small amount of background.
The following two videos, produced by Rob Draper,ACS at Singlemalt TV, feature Andrew Rankin, Director of Operations & Chief Blender for Morrison Bowmore at Bluegrass Cooperage in Kentucky and Miguel Martine Cooperage in Jerez de la Frontera Spain. The videos show the processes involved and some of the chemistry behind the choice of cask, how they affect flavor profiles and contrast the traditional methods of Sherry Cask production with the highly mechanised, volume driven production of Bourbon Casks in Kentucky.
Production and characteristics of Sherry Casks
Bowmore Distillery, to comply with the very strict definition of Scotch Whisky as laid down by the Scotch Whisky Association, ages their single malt whisky in two types of cask…Bourbon and Sherry. Aging in used casks is a stipulation and imparts flavor characteristics to the whisky desired by Master Blenders. It is important to note that Scotch whisky is never aged in raw, unseasoned oak as the subtleties of the whisky would be completely dominated by the wood, destroying the flavor of the raw spirit. As a result the casks used at Marshall Wharf have first been used to age either sherry (in Spain) or Bourbon (in Kentucky) and then they are used to age the Bowmore single malts in Scotland.
Production and characteristics of Bourbon Casks
Aside from the characteristics inherent in the two different types of wood, Quercus Robur (European Red Oak) and Quercus Alba (American White Oak), the casks are infused with the flavors of the respective liquids that have been aged in them over the years. When used to age the already complex Marshall Wharf beers, these casks impart hints of all the characteristics of the type of wood, the sherry or bourbon and finally the Scotch Whisky, to the beers resulting in an amazing range of flavors on the nose and on the palate. The beers also develop a strong body which gives the beer a full and rewarding mouthfeel and long complex finish.