Effective beverage filtration mediaPrecoat Filtration with D.E. (Kieselguhr) is the most widespread method of beer filtration today
Diatomaceous Earth is an excellent filter aid for the primary clarification of beer and wine, due to its high surface area. The powdery substance is coated onto a filter surface (reinforcement or sheet) to form a cake. The cake of filter aid and retained solids is responsible for the filtration effect. The DE diatoms fine pores are so small that they actually trap "chill haze". So it makes for a very clear beer (the remaining haze can only be "seen" using a haze meter).
DE is often used in combination with paper filters because of its ability to remove fine particles from beer without affecting the color, flavor, or body.
Calcined grades of DE are termed kieselguhr; fine, medium and coarse grades may be blended to accomplish the level of clarity required by the brewery. Fine grades provides a higher clarification, but does not provide as high a surface area (thus dirt holding capacity) as medium and coarse grades. DE consumption for beer filtration ranges between 70 and 200g per hL of beer; normal usage is about 100 g/hL. Other filter aids, including perlite and cellulose, are commonly combined with DE, though these aids are better suited for pre-coat applications to enhance cake formation.
DE has been approved by NZ Food Safety as a generally permitted processing aid and also as a permitted aid for organic wines.
It has also been approved under the BioGro Organic Standards for organic wine production.