Malt and other grains (rice, corn) can dissolve well after grinding, so the quality of grinding plays an important role in the composition of wort, biochemical changes, clarification of wort and utilization of raw materials in the saccharification process.
Theoretically, if the malt is more adequately ground, its components can be more fully and rapidly dissolved, which means that chemical and enzymatic reactions can be carried out more easily. However, in practice, the malt cannot be ground too fully because the nature of malt and starch granules are different, so the malt needs to be ground only to a certain extent.
Considering the quality of the wort, the destruction of the bare skins should be as low as possible, because the main components of the bare skins are cellulose, as well as malt polyphenols and bitter compounds, which have a bad effect on the color and taste of the beer, and for cellulose, which is almost insoluble in water, so it has less influence on the wort.
The extract of wort is mainly from endosperm. Endosperm consists mainly of starch, carbohydrates and proteins, and when these main components are dissolved into the mixture, the malt can be fully utilized. Therefore, the endosperm should be ground finely, but not into flour, which would make the washed-out spent grain bed less permeable if that were the case. Another factor is that if the malt endosperm is not internally anisotropic, then the hardness of the malt will be different, then the roller press will have different mechanical resistance so that the malt will be milled unevenly.