A Foeder, pronounced ‘food-er’, is a really, really large barrel, typically oak, used in fermenting, and aging beer. Fermenting beer in oak picks up less oak characteristics. But when aged in oak, the alcohol picks up more of the oak notes. Some Foeder’s are as big as 600 liters, which is around 160 gallons, or roughly three times the size of the average oak barrel. Many beer styles rely on Foeders, like last weeks beer style the Flemish Red Ale.
They are often used in making sour beers, but this is not always the case. Some brewers may want to impart strong oak flavors into a beer. Its also fairly common for brewers to blend younger beer, with beer that has been aging in the Foeder. Lagers, sours, stouts, brown ales, and porters are all common styles aged in Foeders. These vessels allow a slow ingress of oxygen into the beer that is easily watched over with the tasting valve. The high beer to wood ratio, and larger capacity capabilities allow the beer to mature and develop evenly, whereas smaller barrels may progress sooner, possibly acidifying before the beer is fully developed. Because the beer is coming from one vessel, you will have a much more consistent and reproducible product. Foeders will also save on time and labor compared with racking multiple barrels or pulling multiple nails when sampling.
Foeders can definitely be cleaned, and always are as all beer equipment has to be very sterile. However, if a brewer is doing sours, that barrel remains a barrel for all souring. This is because once a barrel goes sour, it can never really go back. Those souring cultures are forever embedded in all the nooks and crannies of the oak. But also, it becomes the brewers own personal culture, giving many beers distinct characteristics and flavors associated with the breweries beers.
Petrus Aged Red ale, and Rodenbach Grand Cru are great examples of beers that have been aged in Foeders. “Petrus Aged Red is a blend of 15% Petrus Aged Pale, pure foeder beer that has been aged for 2 years in oak foeders, and 85% double brown with sour cherries. For the fruit beer lover, but with an ideal sweet-sour balance.” BeerAdvocate