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» » FilteringAll aspects of filtering in the brewing of craft beverages
by Steve Parkes
Owner and lead instructor at American Brewer’s Guild
Diatomaceous Earth (DE) filters are a large class of filters that are used in many industries for a variety of liquid-to-solid separation tasks. They are used throughout the beverage industry to remove particulate matter and produce clear product. Many small breweries employ them to remove yeast and haze from beer before packaging or serving.
In the case of pub breweries, the entire beer clarification process is accomplished with the use of sheet or lenticular filters. However, for larger producers, especially package brewers, separation into separate clarification steps helps to reduce costs and achieve longer term beer stability.
Generally there are four main clarification stages including primary filtration, trap filtration, fine filtration and final membrane filtration. Filtration at each stage is for a particular purpose:
1. Primary filtration removes solids and bulk yeast from the beer.
2. Trap filtration removes DE or other process additives
3. Fine filtration may reduce yeast level and removes fine particulates that could foul a final membrane filter.
4. Final membrane filtration removes organisms (bacteria and yeast) that could spoil the packaged beer.
In the case of pub breweries, the entire beer clarification process is accomplished with the use of sheet or lenticular filters. However, for larger producers, especially package brewers, separation into separate clarification steps helps to reduce costs and achieve longer term beer stability.
Filtration involves the separation of a turbid fluid (unfiltered beer) to produce a clean filtrate and retentate, or residue, via a filter medium. Separation mechanisms include dead end filtration (one-way) and tangential flow filtration (cross-flow). High solids applications like yeast removal from green or fermented beer requires methods that can efficiently handle high loads, such as DE or cross-flow systems. Filtration downstream of DE generally includes particle and microorganism reducing depth and membrane filters to achieve beer brightness and stability. These methods utilize depth or surface filtration, and in some cases, a combination of both.
DE Systems
Diatomaceous earth (DE) is the fossilized remains of single-celled diatoms, consisting mostly of silicon dioxide (85-90%) and up to 4% aluminum oxide. Deposits are mined from a few regions, including the western USA, Canada, Australia, Italy, France (Auvergne) and Germany (Lüneburger Heide). DE is an excellent filter aid for the primary clarification of beer, due to its high surface area. These powdery substances are 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.
Brewing beer during the 1800’s was a local endeavor. Individual villages and towns could have as many as twenty local breweries. By 1850, large cities like Munich, Prague and New York had hundreds of breweries operating. The main limiting factor for brewery growth was the short shelf life of the beer, allowing only a distribution time of 3 to 10 days before the beer showed a sharp drop in quality. This poor quality was primarily due to yeast autolysis and beer spoiling organism, and protein/polyphenol formations.
What was the impact of filtration? Brewers became able to produce a beer that was (more or less) free from spoilage bacteria and even more important, free from yeast. Beer quality became more reliable and constant as the consumer enjoyed a range of beer brewed in various regions. A global market was created. At the first world exhibition in Paris in 1889 you could already taste filtered beers from all over the world.
Beyond removal of yeast and bacteria from beer, breweries today use filters (and aids) to remove proteins, polyphenols, short and long chain carbohydrates and other substances that cause beer haze. Other filtration processes that contribute to brewery quality and productivity are beer recovery, water (brewing and service), CO2 and air/steam.
Filtration of beer is quite a new development, considering the 6,000 year old history of brewing. The first beer filter was presented at a brewing exhibition in Munich in 1880 by German developer Lorenz Adelbert Enzinger. The filter was designed in a horizontal configuration, with individual plates having inlet and outlet channels, similar to modern plate and frame filters. Back then, the plate material was black iron; valves and meters where made from copper and brass. Filter media was made of paper leaves which had to be changed after each filtration.
The next generation of beer filters was developed early in the 1900’s, again by Enzinger. This filter was a vertical design using brass bowls (Enzinger Schalen) to house pulp cakes. Pulp cake was prepared from cotton fibers mixed with asbestos. The main advantage of pulp filtration was the possibility to re-use the material for 3 to 5 filtration batches, reducing labor and downtime. Once spent, the pulp cake was removed from the brass bowls, rinsed and reprocessed in a pulp press to make new cakes. Pulp filtration was the first recycling technology used in a brewery; however it required high water consumption and labor.
Pulp filtration dominated the brewing industry until 1930, when the first Diatomaceous Earth (DE) filter was proven in the US. Shortly after WWII, US, English and Japanese breweries adopted the process and made DE filtration industry standard for primary beer clarification.
Filtration provides the brilliant clarity and microbiological stability evident in most beer sold around the globe today. Brewery growth, whether craft or mainstream brands, involves reaching a broad base of increasingly educated consumers. Filtration helps breweries achieve these sales and brand quality objectives by producing bright beer with excellent taste and microbiological stability.
Answers to all your questions.
* History of Beer Filtration
* Why Filtration?
* Filter Media and Equipment
* DE Systems
* Filters Sheets
* Lenticular Sheet Filters
* Depth Filter Cartridges
* Membrane Cartridges
* Cross-flow Filters
* Brewery Filtration Applications
* Primary Filtration
* Trap (Particle) Filtration
* Fine/Final Filtration
* Beer Recovery
* Utilities Filtration