The actual effect of the wort preparation process has a great relationship with the release rate of the enzymes and extractables in the malt raw materials in water. To effectively and optimally release enzymes and extracts, the following basic conditions are required:
1. The granularity of malt after crushing, that is, the specific surface area of the material;
2. The degree and speed of dispersing malt crushed particles, that is, mixing conditions;
3. The medium environment where the malt crushed particles are dispersed, that is, the ratio, temperature and density of solid phase and liquid phase materials.
In order to control a reasonable degree of pulverization, it is necessary to meet the granularity of the malt after pulverization and to meet the above three basic conditions.
1. In theory:
Theoretically, the finer the malt is crushed, the faster and more complete the dissolution of its contents will be, and the chemical and enzymatic reactions will be easier to proceed, so the best yield can be obtained. The particle size is very small and the specific surface area is very large, which is definitely beneficial to the leaching of the material components. However, the too fine particles are easy to agglomerate and form agglomerates when mixed with water, and the leaching effect will be poor; secondly, in the raw materials Some parts such as crude fiber and crude protein cannot be hydrolyzed during saccharification. If this part of undecomposed particles is very fine, it will block the filter gap of the wort filter layer and affect the wort filtration. Therefore, malt cannot be crushed too finely in actual production, because malt and starch granules have different properties, and the crushing of malt only needs to reach a certain degree.
2. From the aspect of wort quality:
The damage to the bark should be as small as possible. In addition to the main constituent cellulose, wheat husk also contains a series of other soluble substances that can enter the wort, such as malt polyphenols, bitter substances, silicates, and proteins. Both chroma and taste will have an undesirable effect. Since cellulose is insoluble in water and hardly changes due to the action of enzymes, it has little effect on wort.
3. Wheat husks should not be crushed too finely:
Wheat husks are tough and have mechanical resistance to the pulverizer. It is difficult to grind, especially when the malt moisture is high. Wheat husks should not be crushed too finely, because wheat husks can form a natural filter layer. If the malt is crushed too finely, it will reduce the filtration performance of the wort and even cause serious filtration difficulties. In addition, if the malt is crushed too finely, the volume of the material becomes smaller, and the malt powder is tightly packed together, which will inevitably increase the outflow of wort and the difficulty of washing the spent grains. Unless equipped with special wort filtration equipment, powder can be crushed, which is not limited by the degree of wheat husk crushing.
4. The extract of wort mainly comes from endosperm:
The endosperm is mainly composed of starch and other carbohydrates and proteins. The malt can be fully utilized when all the constituents of the endosperm are dissolved. Therefore, the endosperm should be crushed finer, but not as fine as flour, otherwise the permeability of the filter grain layer will become poor. For example, the internal composition of malt endosperm is not balanced, the hardness of each part of the malt kernel is different, and the mechanical resistance to energy produced by the malt is also different. Therefore, the malt is not evenly crushed.