In 2009, the Koningshoeven Brewery reinstated an old tradition by aging La Trappe Quadrupel in oak barrels, thus creating a unique Trappist ale with a perfectly balanced flavour, special aroma of wood, and an alcohol content of 11%. The complex taste depends on the type of barrel in which it is aged and therefore, each batch is different. The ale continues to ferment after bottling, may be kept for many years, and offers real indulgence to the genuine ale lover. The aging process involves new as well as used barrels. The tantalising combination of flavours thereby created depends on the drink that had been previously stored in the barrels, whether it was port, whisky, wine, or brandy. The ultimate taste is also affected by the type of wood the barrel is made from. New oak casks, for example, give the ale its characteristic tannins, which impart a delicate vanilla and almond flavour.