Petrus Roodbruin is a blend of 33% Petrus Aged Pale, pure foeder beer that has been 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 Roodbruin is a typically Flemish red ale as tradition dictates.