Oud Bruin is also know as Flanders Brown and has its origin int the Flemish region of Belgium. The word "oud bruin" means "old brown" and refers to the long aging process (up to 1 year). Oud Bruin undergoes a secondary fermentation which is followed by bottled aging. This will result in settling of the yeast (and bacteria) and a sour flavor. Alcohol (abv) is between 4 -8 %. It's bitterness is about 15 to 20 IBU.