What Is Beer Filtration?
The process of removing the solids (particles) from beer liquid is done by passing it through or across a filter medium. The filtration process hinges on two factors: the filter’s porosity and the size of the particles. Many beer types depend on the clear, golden transparency of the brew as part of their brand recognition. This is why filtration methods and the equipment that provides it is an essential brewery process.
Filtration isn’t only used to make the beer clear. It is also used to purify the beer and make it sterile. There are many processes in brewery production that focus on sterilization and purification, and filtering is one of them.
Particles suspended in the beer liquid remain in/on the filter medium because they are larger than the porosity of the filter material. Filtration is used throughout the world as part of the beer making process, although there are some delicious opaque ethnic beers produced by some cultures that are only passed through a muslin cloth before bottling and fermenting.
Most beers produced today undergo filtration of some sort. It is the size of the particles inside the beer liquid that offers the brewer a vast range of material size. Filtration can simply remove hops after the kettle boil or eliminate particles on a molecular level.
There are 2 types of filtration in the brewery process:
- Depth Filtration
Depth filtration is also called powder, primary, or rough filtration. It is a process whereby the beer is passed through a labyrinthian mesh of channels that trap the particles. Inside the channels, there is a filter material of some kind.
- Porous media (ceramic membranes, filter cake, etc)
- Diatomaceous earth (DE; Kieselguhr)
In many small home breweries, depth filtration is the only method of filtering the beer liquid needs to undergo.
- Surface filtration
Surface filtration is when a thin film of material is used as a filter medium. It is a very basic filter method and often seen used in kitchens and households when a liquid requires clarification. The cloudy particles are caught by the filter material and the clarified liquid pools below. The less porous the filter mesh, the more clarification the end product will have.