However, brewers require the rate of protein modification to be controlled, to produce malts from which worts can be obtained that contain enough of the soluble nitrogen and amino acids needed for optimal yeast nutrition, whilst maintaining high levels of hydrolytic enzymes and enough proteins for beer foam stability. A greater understanding of the mechanisms underlying relative protein, starch and cell wall modification, the bases of varietal differences in these processes, and the ability to select for them in a breeding program needs to be gained. In particular, a greater understanding of protein degradation during modification is an important research target.