Coffee filter

A basket-type coffee filter, here made of bleached paper

Used coffee filter

A coffee filter is a filter used for brewing coffee. Filters made of paper (disposable), or cloth, plastic, and metal (reusable) are used. The filter allows the liquid coffee to flow through, but traps the coffee grounds.

Paper filters remove oily components called diterpenes; these organic compounds, present in unfiltered coffee, have anti-inflammatory properties. Metal or nylon mesh filters do not remove these components.

History

On July 8, 1908, the first paper coffee filter was invented by German entrepreneur Melitta Bentz. She wanted to remove the bitter taste caused by overbrewing. She patented her invention and formed a company, Melitta, to sell the coffee filters, hiring her husband and two sons to assist her as the first employees.

The Flemish coffee Rombouts company was founded in Antwerp in 1896. In 1958 the company launched its first One Cup Coffee Filter for the Brussels World Exhibition, allowing a cup of coffee to be made using the perfect amount of roasted and ground coffee. In 1964 the company began marketing the concept and enjoyed much success in the horeca and retail sectors. In 1966 Rombouts was appointed a "Certified Royal Warrant Holder of Belgium".

Paper filter

Cone-type coffee filter, made of unbleached paper

Main article: Filter paper

Coffee filters of paper are made from about 100 g/m² filter paper. The raw materials (pulp) for the filter paper are coarse long fiber, often from fast-growing trees. Both bleached and unbleached filters are made.

Typically coffee filters are made up of filaments approximately 20 micrometres wide, which allow particles through that are less than approximately 10 to 15 micrometres.

For a filter to be compatible with a coffee maker, the filter needs to be a specific shape and size. Common in the US are cone-shaped filters #2, #4, and #6, as well as basket-shaped filters in an 8–12 cup home size and larger restaurant sizes.

Other important parameters are strength, compatibility, efficiency and capacity.

If a coffee filter is not strong enough, it will tear or rupture, allowing coffee grains through to the coffee pot. Compatibility describes a filter medium's resistance to degradation by heat and chemical attack; a filter that is not compatible with the liquid passing through it is likely to break down, losing strength (structural failure). Efficiency is the retention of particles in a target (size) category. The efficiency is dictated by the particles or substances to be removed. A large-mesh filter may be efficient at retaining large particles but inefficient at retaining small particles. Capacity is the ability to "hold" previously removed particles while allowing further flow. A very efficient filter may show poor capacity, causing increased resistance to flow or other problems as it plugging up prematurely and increasing resistance or flow problems. A balance between particle capture and flow requirements must be met while ensuring integrity.

Other types

Reusable metal filters are also used to prepare filtered coffee, including Vietnamese iced coffee and Indian filter coffee. The "French press" (also referred to as cafetière) uses a metal filter.

Cloth, also reusable, has been used to filter coffee for a very long time. Like paper, it strains out the coffee grounds, but the typical cloth filter allows more of the oil to come through than typical paper filters.

See also

• Trescol Coffee Filter
• Drip brew
• Coffee pod (coffee bag)
• Single-serve coffee container
• Tea bag or tea ball