The filtration of craft beer is very important. The use of filter materials makes the beer clear and translucent without adding suspended solids. Filter plates can be made of fiber, cotton, diatomaceous earth, perlite, fiberglass and other materials. There are many kinds of filter plates, which can meet the needs of different filtration precisions until sterile filtration. Two common filter aids in craft breweries are diatomaceous earth and perlite.
Perlite is mainly an amorphous mineral rock produced by the volcanic eruption of volcanic ash. It is molten potassium, sodium and aluminosilicate, and has strong chemical inertness. The perlite produced by crushing, calcining and sieving perlite ore has properties very similar to diatomite, but has many differences from diatomite. shape.
Perlite is a very light powder with loose particles. The volume mass is about 20%~40% smaller than that of diatomite, and its permeability is better than that of diatomite. Therefore, it is a very good filter material.
Perlite can be used alone or mixed with diatomite. Its particle size distribution is 7~100um, and there are 4~6 specifications and models, such as the most fine soil, fine soil, medium coarse soil, etc. Relatively speaking, the particle size distribution of each type of perlite will be more uniform than that of diatomite. Because of its strong permeability, and its relatively small volume and quality, the consumption when filtering beer is lower than that of diatomite. earth. The density of perlite is lower than that of diatomite. When perlite is used alone for blending, it is easy to float on the liquid surface. Therefore, the mixer of the mixing tank should be slightly modified to make the up and down stirring effect better. If perlite and diatomite are used in combination, the effect is not significant. When the pH value is relatively low, potassium and iron are easily precipitated from perlite during the whole process of filtration. Therefore, perlite is more suitable for wort filtration, because the pH value of wort is 5.2~5.5.
