The concept of hop utilization, unlike that of other parts of the brewing process, is undergoing radical change. The main consideration is to impart bitterness, earlier views, e.g., on preservative action, having proved less substantial. Bittering value extends beyond numerical assessments and depends to some extent on the production of acceptable mixtures of bittering components. The mixture actually encountered depends (a) on brewing conditions and (b) on the history of the hop or hop preparation. Under (a) the choice of mash grist, boiling conditions, and fermentation factors are of importance. Under (b), oxidation of each of the grain relevant hop resin components leading to products of varying bitterness is a substantial factor.