A process for obtaining a starch and a protein or both from grain flour, the process steps comprising: providing grain flour; mixing the grain flour with processed or fresh water to form a slurry; separating the slurry into it at least two fractions, the at least two fractions including two or more of a heavy A-starch fraction, a protein and B-starch fraction, and a pentosan fraction; and generating a biogas from at least one of the fractions from the separating step, the biogas being used for generating energy.