Petrus Roodbruin, previously called Oud Bruin, is a blend of 33% Petrus Aged Pale, pure foeder beer that has aged for 2 years in oak foeders, and 67% young brown beer. In this blend, the young dark beer contributes the reddish-brown color and the Aged Pale contributes the slightly sour flavor. Petrus Oud Bruin is a typically Flemish red-brown ale as the tradition dictates.