Coffee filter
A coffee filter is a filter used for various coffee brewing methods including but not limited to drip coffee filtering. Filters made of paper, cloth, or plastic, metal or porcelain are used. Paper and cloth filters require the use of some kind of filter holder, whereas filters made out of other materials may present an integral part of the holder or not, depending on construction. The filter allows the liquid coffee to flow through, but traps the coffee grounds.
Overview
Paper filters remove oily components called diterpenes. Metal, nylon or porcelain mesh filters do not remove these components. These organic compounds, present in unfiltered coffee, have anti-inflammatory properties. Several studies also indicate that the mild consumption of paper-filtered coffee may reduce the risk of coronary heart disease due to reducing these compounds.Coffee filters of paper are made from about 100 g/m2 filter paper. The raw materials for the filter paper are coarse long fiber, often from fast-growing trees, e.g. Melitta has used up to 60% bamboo in their filters since 1998. 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.
Some baristas claim that paper filters exhibit a "paperish" taste and recommend washing out the filter with a flush of hot water before filling the ground coffee into the filter.
Since paper filters filter out some components the resulting coffee is said to taste somewhat fruitier compared to permanent filters.
For a filter to be compatible with a filter holder or coffee maker, the filter needs to be a specific shape and size.
Disposable paper filters
History of paper filters
In 1782-79, Johann Georg Krünitz described a then-new method to extract coffee utilizing blotting paper in a metal filter cone shape like.In Germany and the Netherlands, filter paper inserts were used in narrow conical metal filter holders called "Hamburger Spitztrichter" to extract drip coffee. In 1785, a silver filter was manufactured by Johann Christopher Hellmers, suggesting that porcelain versions existed even earlier. Hamburg filters made out of metal or porcelain were still very common in the early 1900s in Germany.
In 1847, experimented with paper filters while constructing an early "air press coffee machine".
In 1885, Heinrich Böhnke-Reich warned of using old wall paper as coffee filters, but favorably described sheets of thick wool-style greyish paper which could be cut into shape for use as quick filters in a conical filter holder.
In 1894, the Wilda'sche coffee filter device by Eugen Wilda used single-use cloth filter bags, which, in the corresponding patent, were considered to be superior to paper filter bags presumably already in use at the time.
On 8 July 1908, the first commercial paper coffee filter was a 94 mm round filter disk devised by the 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.
Filter shapes and sizes
Cone-, fan- or boat-shaped filters
Melitta filter systems and derivatives
Since 1930/1931, there was a conical paper coffee filter named "Blitz-Filter" featuring rims manufactured by the Berlin-based Blitz-Filter GmbH, a filter paper manufacturer, holding a D.R.G.M. utility patent on their filter. In 1931, Paul Ciupka proposed conical paper coffee filters, which reportedly led to the construction of another coffee filter named "Brasil Kaffeefilter" at the in 1932. It was recommended by the press. Melitta bought the rights to the Göttingen D.R.G.M. filter patent and, still in 1932, introduced their Schnell-Filter, a cone-shaped filter holder looking almost identical to the Brasil filter with a circular bottom with 8 holes suitable for use with squarish sheets of filter paper, which still had to be pressed into shape through a metal cone. These quick filter holders were manufactured of porcelain or metal, available in sizes named "100", "101", "102", and "103". This system was available up to 1939.Patented in 1935, Melitta introduced the Filtertüte in various sizes in 1936 or 1937 In Germany, Melitta holds a trademark on the term "Filtertüte" for the conical fan- or boat-shaped paper filter introduced in 1937, that is why other manufacturers use terms like coffee filter, paper filter, etc.
In 1936, Melitta also took over the manufacturer of the "Blitz-Filter". The cone-shaped filter holders were refined in 1936 to get a slot-shaped bottom more suitable for the filter bags, now looking more fan- or boat-shaped. Over the years the system was expanded to eventually consist of filter bag sizes "100", "101", "102", "103", "104", "105", "106", "112" and "123". The system also included special types like tea filters "401" and "402" and the miniature filter "801". Brigitta once marketed a fan- or boat-shaped filter size "502". A disadvantage of the system was that one had to pour water continuously or several times while the proper amount of necessary water could only be guessed.
Therefore, in 1963 or 1965 Melitta developed a new fan- or boat-shaped filter system with corresponding "1×" nomenclature: In this system the filters are sized big enough so that the whole amount of water can be poured in one go. Consequently, the filter sizes "1×2", "1×4", "1×6" and "1×10" result in 2, 4, 6, and 10 cups of coffee when filling the filter once. Since these filters only differ in height and have otherwise the exact same geometry, bottom width and angle, the filter bags are interchangeable between filter holders of different sizes.
Both systems are still in use today in principle, but the sizes "101", "103", "104", "105", "106", "112", "123", "401", "402", "801" and "1×10" are no longer manufactured.
Common in the US are fan- or boat-shaped filters "#0", "#1", "#2", "#4", and "#6", with "#2", "#4" and "#6" being particularly popular, as well as basket-shaped filters in an 8–12 cup home size and larger restaurant sizes.
Hario filter system
The "vector 60" V60 is a cone-shaped brewer, with ribs along the wall and a single large hole.Hario began designing brewers in 1980; the V60 design was released in 2004.
The brewer received the Japanese Good Design Award in 2007
and is used by many of the winners in the World Brewers Cup. In partnership with 2013 World Barista Champion Pete Licata it was further developed into the Hario W60, a brewer with a flat-bottomed mesh filter, to "address the concern baristas have with 'flat bed' brewing".
The Hario Switch combines steeping with drip filtering.
Hario has cone-shaped paper filter bag sizes "01", "02" and "03".
Other filter shapes
Saint Anthony Industries introduced a conical filter called "C70" and a flat-bottom filter "F70" with a steep 70° angle.Other Melitta filter sizes include the pyramid filters "202s", "203", "206", "220", "240" and "270", round filter disks "1", "1a", "2" and "2b", and "50", circle filter rings "3 in.", "164mm", "190mm", "203mm", "235mm", "240mm", "244mm", "256mm", "260mm", "290mm", "330mm", "400mm" and "440mm", prepleated flat-bottom basket filters "250/90" and "250/110", roll filters "2004" as well as wrap filters. While some of them are still available today, most of them have fallen out of use for long.
A squarish pyramid filter Filtra "602" was available as well.
Other basket filter sizes include "101/317", "152/350", "152/457", "203/533" and "280/635".
Other round filter disks include 160 mm, 220 mm, 195 mm, 230 mm.
The Aeropress and Ceado Hoop use round paper filter disks with a diameter of c. 63 mm.
The German Tricolate coffee dripper uses round paper filter disks with a diameter of 88 mm.
The Kanas-based NextLevel drippers use proprietary round disk paper filters as well.
The Hario cold brew dripper Slow Brew "Shizuku" and Water Dripper Clear take 58 mm round filter disks.
Chemex filter system
The six conical filter holder sizes for the Chemex coffee maker and the Funnex utilize two different sizes of paper filters. A half-moon shaped filter paper is used for the 3-cup holders and the Funnex, which must be folded before use. The larger holders for 5, 6, 8, 10 and 13 cups can alternatively use prefolded square sheets, prefolded circle filters or unfolded circle filters. The paper is 20–30% thicker than regular paper filters.Other filter parameters and properties
Other important coffee filter paper 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. Efficiency is the retention of particles in a target 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.