Drip coffee

Last updated

Water seeps through the ground coffee and the paper filter and is then collected in a container placed below a holder used for drip brewing. TEDxAMS2011 044.JPG
Water seeps through the ground coffee and the paper filter and is then collected in a container placed below a holder used for drip brewing.

Drip coffee is made by pouring hot water onto ground coffee beans, allowing it to brew. There are several methods for doing this, including using a filter. Terms used for the resulting coffee often reflect the method used, such as drip-brewed coffee, or, somewhat inaccurately, filtered coffee in general. Manually brewed drip coffee is typically referred to as pour-over coffee. [1] [2] Water seeps through the ground coffee, absorbing its constituent chemical compounds, and then passes through a filter. The used coffee grounds are retained in the filter, while the brewed coffee is collected in a vessel such as a carafe or pot.

Contents

History

Commercial paper coffee filters were invented in Germany by Melitta Bentz in 1908 [3] [4] and are commonly used for drip brew all over the world. In 1944, Willy Brand developed an automatic drip-brewer utilizing circular paper filters in Switzerland. [5] :144 In 1954, one of the first electric drip brewers, the Wigomat invented by Gottlob Widmann, was patented in Germany. [6] Drip brew coffee makers largely replaced the coffee percolator (a device combining boiling, drip-brewing and steeping) in the 1970s due to the percolator's tendency to over-extract coffee, thereby making it bitter. [7] One benefit of paper filters is that the used grounds and the filter may be disposed together, without a need to clean the filter. Permanent filters are also common, made of thin perforated metal sheets, fine plastic mesh, porous ceramics or glazed porcelain sieves that restrain the grounds but allow the coffee to pass, thus eliminating the need to have to purchase separate filters which sometimes cannot be found in some parts of the world. These add to the maintenance of the machine but reduce overall cost and produce less waste.

Characteristics

Brewing with a paper filter produces clear, light-bodied coffee. While free of sediments, such coffee is lacking in some of coffee's oils and essences; they have been trapped in the paper filter. [8] Metal, nylon or porcelain mesh filters do not normally remove these components. [9]

It may be observed, especially when using a tall, narrow carafe, that the coffee at the bottom of the coffeepot is stronger than that at the top. This is because less flavor is available for extraction from the coffee grounds as the brewing process progresses. A mathematical argument has been made that delivering comparable strength in two cups of coffee is nearly achieved using a Thue–Morse sequence of pours. [10] This analysis prompted a whimsical article in the popular press. [11]

Cultural impact

Coffee drips through coffee grounds and filters into several jars in a specialty coffee shop. Drip Coffee Bangkok.jpg
Coffee drips through coffee grounds and filters into several jars in a specialty coffee shop.

Filter coffee is central to Japanese coffee culture and connoisseurship. [12]

In South India, filter coffee brewed at home is known as Kaapi and is a part of local culture. Most houses have a stainless-steel coffee filter and most shops sell freshly roasted and ground coffee beans. Some popular filter coffee brands include Mysore café, Hill coffee (Suresh healthcare), Cothas Coffee (Bangalore) and Narasu's Coffee (Salem). It is common in South India and Louisiana to add chicory to coffee to give it a unique taste and flavour. [13]

Methods

There are a number of methods and pieces of equipment for making drip-brewed coffee.

Manual pour-over coffee preparation

Manual drip (pour-over) coffee Manual drip (pour-over) coffee.jpg
Manual drip (pour-over) coffee

Pour-over methods are popular ways of making specialty drip coffee. The method involves pouring water over a bed of coffee in a filter-lined conical or cylindrical chamber typically consisting of a filter and a suitable filter holder. The filtering can be with paper, cloth, plastic, ceramics, or metal. [14] [15]

The quality of the resulting coffee is extremely dependent on the technique of the user, with pour-over brewing being a popular method used in the World Brewers Cup. [15] [16]

The pour-over coffee preparation method typically starts by pouring a small amount of hot water over the coffee grounds and allow it to sit for about half a minute before continuing the pouring. This pre-wetting, called blooming, will cause carbon dioxide to be released in bubbles or foam from the coffee grounds and helps to improve the taste.

There are several manual drip-brewing devices on the market, offering more control over brewing parameters than automatic machines, and which incorporate stopper valves and other innovations that offer greater control over steeping time and the proportion of coffee to water. There also exist small, portable, single-serving drip brew makers that only hold the filter and rest on top of a mug or cup, making them a popular option for backcountry campers and hikers. Hot water is poured in and drips directly into the cup.

Different filter shapes and sizes exist, most notable the (paper) coffee filter systems introduced by Melitta (1908, 1932, 1936, 1965), Chemex (1941) and Hario (2004).

Disposable single serve drip coffee bag

Disposable single serve drip coffee bag Bacha Coffee Moomin mug.jpg
Disposable single serve drip coffee bag

Especially in East Asia disposable single serve drip coffee bags are common way to prepare drip coffee. The coffee is packed inside the device. There is typically perforated top edge which is peeled off to open the bag. The device contains cardboard supports to spread it over the cup. Hot water is poured from a kettle or anything that can boil the water until the lower edge of the bag gets in contact with the surface of the coffee. The benefit of this method is extremely low investment cost on equipment required to prepare decent coffee. [17]

Manual drip-coffee makers

Cafetière du Belloy and similar coffee makers

Enameled metal French drip coffee pot Cafetiere orange - gauche.jpg
Enameled metal French drip coffee pot
Porcelain French drip coffee pot, with round drilled holes of the filter visible Cafetiere a percolation en faience creme 16.jpg
Porcelain French drip coffee pot, with round drilled holes of the filter visible

Manual drip coffee makers include the so-called French drip coffee pot (invented in 1795 by François Antoine Henri Descroizilles  [ de ] and manufactured by a metal-smith in Rouen, [18] [19] then popularized by bishop Jean-Baptiste de Belloy [18] [19] for why it became known as Cafetière du Belloy  [ de ] in Paris since 1800 [20] [21] to the point that it was sometimes incorrectly attributed to the bishop himself [22] [21] ), the Grègue  [ fr ] (café grègue, café coulé, etc.) [23] originating from La Réunion and also common in Louisiana, and the so-called Arndt'sche Caffee-Aufgussmaschine (Quedlinburg, Germany, c. 1900). French drip devices emerged from the earlier coffee biggins where cloth filters would be fully inserted into the pot for steeping instead of drip filtering. [24] French drip coffee pots don't use paper filters but a permanent filter featuring many small round drilled holes made out of (enameled) metal, ceramics or porcelain. A cafetière du Belloy was originally made out of tin, later versions were made out of silver, copper, ceramics or porcelain. The Grègue and the Arndt'sche Caffee-Aufgussmaschine are built out of (enameled) metal. To avoid sediments in the coffee, coarsely ground coffee has to be used.

Around 1895, skyblue enameled metal coffee pots named Madam Blå  [ da ] were introduced in Denmark by Glud & Marstrand. They looked similar to French drip coffee pots, but used cotton filters and were available in 18 sizes for up to 50 cups of coffee.

A complete Drip-O-lator unit Dripolator014.jpg
A complete Drip-O-lator unit

The Drip-O-lator is an American coffee pot for making drip coffee patented in 1921 and in 1930 and manufactured in Massillon, Ohio, [25] or Macon, Georgia, [26] United States. The production of Drip-O-lators ceased in the middle of the twentieth century. The pots have become collectibles similar to bric-à-brac. [27]

In the 1930s, the German company Melitta produced a series of manual coffee makers called Kaffeefiltriermaschine ("coffee filtering machine"). They worked on the principle of French drip coffee pots, but used a paper filter and allowed to pour the whole amount of water at once instead of having to pour several times. [28]

Flip coffee pots

A less familiar form of drip brewing is the reversible or "flip" pot commonly known as Napoletana (1819) and late-19th century variants like the Russische Eikanne ("Russian egg pot"), Potsdamer Boiler ("Potsdam boiler"), or the Arndt'sche Sturzmaschine (c. 1920).

Karlsbad-style coffee makers

A variant of the category of French drip coffee pots is the group of "Bohemian" coffee pots including the original Karlsbad coffee makers, historically produced by several mostly Bohemian porcelain manufacturers since 1878 up into the first half of the 20th century, and variants produced by Siegmund Paul Meyer (SPM) / Walküre  [ de ] since 1910, [29] [30] [31] [32] now Friesland  [ de ] (FPM). [33] [34] In contrast to French drip coffee pots which feature round holes, they all use a special double-layered cross-slitted strainer made from through-glazed porcelain. [35] [36] Before World War I, they were very popular in the Viennese coffee house culture. The special kind of drip coffee they produce is called a Karlsbader ("Karlsbad coffee"). [35] [37]

System Büttner coffee makers

System Büttner coffee makers are a type of coffee makers featuring a special permanent through-glazed porcelain filter with triangularly-arranged slits and valving mechanism to combine steeping with drip-brewing. They were invented in 1926 by the coffee roaster Carl A. Büttner (Berlin, Germany) [38] and produced up into, at least, the 1940s by the porcelain manufacturer Bauscher  [ de ] (Weiden, Germany) for various German coffee roasters and distributors.

Automatic drip-coffee makers

Moccamaster drip coffee maker. Technivorm Moccamaster K741.64B.jpg
Moccamaster drip coffee maker.

Electric drip-coffee makers

One of the first electrical drip coffee makers was the German Wigomat, patented in 1954. In the early 1970s electrical drip coffee makers became more common, causing a decline in manual drip coffee preparation methods until the 2010s, and the almost extinction of coffee percolators. Among the early electrical drip coffee machines was a machine designed by two former Westinghouse engineers and sold under the brand Mr. Coffee in the early 1970s.

See also

Related Research Articles

<span class="mw-page-title-main">Melitta</span> German coffee company

Melitta is a German company selling coffee, paper coffee filters, and coffee makers, part of the Melitta Group, which has branches in other countries. The company is headquartered in Minden, North Rhine-Westphalia.

<span class="mw-page-title-main">French press</span> Coffee brewing device

A French press, also known as a cafetière, cafetière à piston, caffettiera a stantuffo, press pot, coffee press, or coffee plunger, is a coffee brewing device, although it can also be used for other tasks. The earliest known device was patented in 1852 in France by Jacques-Victor Delforge and Henri-Otto Mayer.

<span class="mw-page-title-main">Coffee filter</span> Coffee brewing utensil

A coffee filter is a filter used for various coffee brewing methods including but not limited to drip coffee filtering. Filters made of paper (disposable), cloth (reusable), or plastic, metal or porcelain (permanent) 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.

<span class="mw-page-title-main">Coffee percolator</span> Coffee brewing device

A coffee percolator is a type of pot used for the brewing of coffee by continually cycling the boiling or nearly boiling brew through the grounds using gravity until the required strength is reached. The grounds are held in a perforated metal filter basket.

<span class="mw-page-title-main">Coffee cup</span> Tableware product

A coffee cup is a container, a cup, for serving coffee and coffee-based drinks. There are three major types: conventional cups used with saucers, mugs used without saucers, and disposable cups. Cups and mugs generally have a handle. Disposable paper cups used for take-out sometimes have fold-out handles, but are more often used with an insulating coffee cup sleeve.

<span class="mw-page-title-main">Neapolitan flip coffee pot</span> Flip-over coffeemaker that relies on gravity

The Neapolitan flip coffee pot is a drip brew coffeemaker for the stove top that was very popular in Italy until the 20th century. Unlike a moka express, a napoletana does not use the pressure of steam to force the water through the coffee, relying instead on gravity.

<span class="mw-page-title-main">Coffee preparation</span> Process of turning coffee beans into a beverage

Coffee preparation is the process of turning coffee beans into liquid coffee. While the particular steps vary with the type of coffee and with the raw materials, the process includes four basic steps: raw coffee beans must be roasted, the roasted coffee beans must then be ground, and the ground coffee must then be mixed with hot or cold water for a specific time (brewed), the liquid coffee extraction must be separated from the used grounds, and finally, if desired, the extracted coffee is combined with other elements of the desired beverage, such as sweeteners, dairy products, dairy alternatives, or toppings.

<span class="mw-page-title-main">Vacuum coffee maker</span> Device used to brew coffee

A vacuum coffee maker brews coffee using two chambers where vapor pressure and gravity produce coffee. This type of coffee maker is also known as vac pot, siphon or syphon coffee maker, and was invented by Loeff of Berlin in the 1830s. These devices have since been used for more than a century in many parts of the world. Design and composition of the vacuum coffee maker varies. The chamber material is borosilicate glass, metal, or plastic, and the filter can be either a glass rod or a screen made of metal, cloth, paper, or nylon. The Napier Vacuum Machine by James Robert Napier, presented in 1840, was an early example of this technique. While vacuum coffee makers generally were excessively complex for everyday use, they were prized for producing a clear brew, and were quite popular until the middle of the twentieth century. Vacuum coffee makers remain popular in some parts of Asia, including Japan and Taiwan. The Bauhaus interpretation of this device can be seen in Gerhard Marcks' Sintrax coffee maker of 1925.

<span class="mw-page-title-main">Melitta Bentz</span> German entrepreneur and inventor of the coffee filter

Amalie Auguste Melitta Bentz, born Amalie Auguste Melitta Liebscher, was a German entrepreneur who invented the paper coffee filter in 1908. She founded the company Melitta, which still operates under family control.

<span class="mw-page-title-main">AeroPress</span> Manual coffee brewer (developed 2004)

The AeroPress is a manual coffeemaker invented by Alan Adler, founder of AeroPress, Inc. It consists of a cylindrical chamber, and a plunger with an airtight silicone seal, similar to a syringe. Ground coffee beans and water are steeped inside, then forced through a filter at the bottom of the chamber by pressing the plunger down through the chamber. It is capable of brewing highly concentrated coffee, which the manufacturer describes as "espresso style", but can also be used to brew filter strength coffee, or cold brew coffee.

<span class="mw-page-title-main">Single-serve coffee container</span> Soft or hard container filled with a single portion of coffee grounds for brewing

A single-serve coffee container is a container filled with coffee grounds, used in coffee brewing to prepare only enough coffee for a single portion. They come in various formats and materials, often either as hard and soft pods or pads made of filter paper, or hard aluminium and plastic capsules.

<span class="mw-page-title-main">Chemex Coffeemaker</span> Pour-over style glass coffeemaker

The Chemex Coffeemaker is a manual pour-over style glass coffeemaker, invented by Peter Schlumbohm in 1941, manufactured by the Chemex Corporation in Chicopee, Massachusetts.

<span class="mw-page-title-main">Coffeemaker</span> Cooking appliance used to brew coffee

A coffeemaker, coffee maker or coffee machine is a cooking appliance used to brew coffee. While there are many different types of coffeemakers, the two most common brewing principles use gravity or pressure to move hot water through coffee grounds. In the most common devices, coffee grounds are placed into a paper or metal filter inside a funnel, which is set over a glass or ceramic coffee pot, a cooking pot in the kettle family. Cold water is poured into a separate chamber, which is then boiled and directed into the funnel and allowed to drip through the grounds under gravity. This is also called automatic drip-brew. Coffee makers that use pressure to force water through the coffee grounds are called espresso makers, and they produce espresso coffee.

Sowden SoftBrew is a coffee brewing device by the designer George Sowden in 2010.

<span class="mw-page-title-main">Chorreador</span> Coffee-making device in Costa Rica

A chorreador is a coffee making device used in Costa Rica in which hot water leaches through coffee grounds held in a cloth filter mounted on a wooden stand, then drips into a container.

<span class="mw-page-title-main">Teapot effect</span> Phenomenon in fluid dynamics

The teapot effect, also known as dribbling, is a fluid dynamics phenomenon that occurs when a liquid being poured from a container runs down the spout or the body of the vessel instead of flowing out in an arc.

<span class="mw-page-title-main">Karlsbad-style coffee maker</span> Special drip coffee maker utilizing a slitted through-glazed porcelain filter

A variant of the category of French drip coffee pots is the group of "Bohemian" coffee pots, manual zero-bypass coffee makers made out of porcelain only, including Karlsbad coffee makers, Bayreuth coffee makers, the Walküre cup filter (2010) and the Walküre aroma-pot (2015). In contrast to French drip coffee pots they all use a special double-layered cross-slitted strainer made from through-glazed porcelain as well as a water spreader with six large round holes to ensure an even water distribution and reduce the agitation of the coffee bed, a method sometimes also called cake filtration. In particular before World War I, but still up to the advent of the Espresso machine in the 1950s, they were very popular in the Viennese coffee house culture. The special kind of drip coffee they produce is called a Karlsbader. In Vienna, the Kleiner Schwarzer, a black coffee without milk or sugar, was often prepared in Karlsbad coffee makers as well.

French coffee maker may refer to:

"System Büttner" coffee makers have been a type of manual and semi-automatic coffee makers combining coffee steeping with drip-filtering (percolation).

References

  1. https://www.barniescoffee.com/blogs/blog/the-difference-between-pour-over-and-drip-brew-coffee
  2. https://www.kitchenaid.com/pinch-of-help/countertop-appliances/drip-vs-pour-over-coffee-whats-difference.html
  3. Hempe, Mechthild (2008). Written at Minden, Germany. Melitta Unternehmensgruppe (ed.). 100 Jahre Melitta - Geschichte eines Markenunternehmens[100 years Melitta - History of a brand company] (in German) (1 ed.). Cologne, Germany: Geschichtsbüro Verlag / Geschichtsbüro Reder, Roeseling & Prüfer GbR. ISBN   978-3-940371-12-6. (2+140+2 pages) (NB. There is also a French translation named 100 années Melitta - L'histoire d'une marque. Reportedly, English and Brazilian translations exist as well.)
  4. "The History of How We Make Coffee". About.com. Archived from the original on 2012-05-26. Retrieved 2012-02-13.
  5. Beutelspacher, Martin (July 2006). "Techniken der Kaffeezubereitung. Auf dem Weg zu einer Optimierung des Kaffeegenusses". In Mohrmann, Ruth-Elisabeth [in German] (ed.). Essen und Trinken in der Moderne. Beiträge zur Volkskultur in Nordwestdeutschland (in German) (1 ed.). Münster, Germany; New York, USA: Waxmann Verlag GmbH / Waxmann Publishing Co.  [ de ]. pp. 125–146. ISBN   978-3-8309-1701-4. ISSN   0724-4096 . Retrieved 2023-06-09. (159+1 pages)
  6. "Sixty years of the Federal Republic of Germany – a retrospective of everyday life" . Retrieved 2012-12-28.
  7. "Perfectcoffeemakers.com". www.perfectcoffeemakers.com. Archived from the original on 2014-03-18. Retrieved 2012-09-18.
  8. "How to Use a Pour Over Brewer" Archived 2011-10-23 at the Wayback Machine CoffeeGeek.com. 2005-10-21.
  9. Cornelis, Marilyn C.; El-Sohemy, Ahamed (November 2007). "Coffee, caffeine, and coronary heart disease". Current Opinion in Clinical Nutrition & Metabolic Care . 10 (6). Lippincott Williams & Wilkins, Inc.: 745–751. doi:10.1097/MCO.0b013e3282f05d81. ISSN   1363-1950. PMID   18089957. S2CID   35221890. Diterpenes present in unfiltered coffee and caffeine each appear to increase risk of coronary heart disease. A lower risk of coronary heart disease among moderate coffee drinkers might be due to antioxidants found in coffee.
  10. Richman, Robert (2001). "Recursive Binary Sequences of Differences" (PDF). Complex Systems. 13 (4): 381–392. Retrieved 2013-02-19.
  11. Abrahams, Marc (2010-07-12). "How to pour the perfect cup of coffee". The Guardian . Retrieved 2013-02-19.
  12. Strand, Oliver (2011-02-09). "Coffee's Slow Dance". The New York Times . Retrieved 2019-12-07.
  13. Thomas, Rans (2012-01-11). "Chicory: A Powerful Perennial". Quality Deer Management Association. Archived from the original on 2012-01-11. Retrieved 2018-09-29.
  14. Carman, Tim (2014-02-08). "For Coffee Fanatics, Only The Best Will Do". The Modesto Bee. Retrieved 2022-08-22.
  15. 1 2 Hoffmann, James Alexander (2014). The world atlas of coffee: from beans to brewing: coffees explored, explained and enjoyed (1 ed.). Richmond Hill, Ontario, Canada: Firefly Books Ltd. ISBN   978-1-77085470-3.
  16. Cadwalader, Zac (2017-07-19). "6 Coffee Recipes From The World Brewers Cup". Sprudge. Retrieved 2022-08-22.
  17. aaaatu (2020-10-27). "Disposable Drip Coffee Filter in Korea". Youtube.com. Retrieved 2024-04-08.
  18. 1 2 Duval, Clément (October 1951). American Chemical Society ACS (ed.). "François Descroizilles, the Inventor of Volumetric Analysis". Journal of Chemical Education. 28 (10). ACS Publications: 508–519. Bibcode:1951JChEd..28..508D. doi:10.1021/ed028p508. ISSN   0021-9584.
  19. 1 2 de Lérue, Jules-Adrien (1875). Notice sur Descroizilles (François-Antoine-Henri) - chimiste, né à Dieppe, et sur les membres de sa famille (in French). C.-F. Lapierre Rouen. pp. 14–16. une cafetière qu'il avait fait fabriquer par un petit ferblantier de Rouen
  20. Ukers, William Harrison [at Wikidata] (1922). "Chapter 34. The Evolution of Coffee Apparatus". All About Coffee (1 ed.). New York, USA: The Tea and Coffee Trade Journal Company. pp. 621–622. De Belloy's (or Du Belloy's) coffee pot appeared in Paris about 1800. It was first made of tin; but later, of porcelain and silver
  21. 1 2 Bramah, Edward Roderick; Bramah, Joan (1995) [1989]. Coffee Makers - 300 years of art & design. Translated by Auerbach, Georg (2 ed.). London, UK: Quiller Press Ltd. ISBN   1-870948-33-5. (2+2+166+8+2 pages) (NB. Original 1989 edition was by Lucchetti editore, Bergamo, Italy.); Bramah, Edward Roderick; Bramah, Joan (1995) [1989]. Kaffeemaschinen - Die Kulturgeschichte der Kaffeeküche[Coffeemachines - The cultural history of the coffee kitchen] (in German). Translated by Auerbach, Georg (Special ed.). Stuttgart, Germany (originally: Munich, Germany): Parkland Verlag (originally: Blanckenstein Verlag). p. 152. ISBN   3-88059-826-6. (168+2 pages) (NB. The German translation contains many typographical errors.)
  22. "(33) 5. BELLOY, Jean-Baptist de (1709–1808)". he invented the filter
  23. Cohen, Patrice (2000). Le cari partagé - Anthropologie de l'alimentation à l'ile de la Réunion. Collection Hommes et sociétés (in French). Karthala éditions. p. 148. ISBN   978-2-84586017-9. (358 pages)
  24. Bersten, Ian; Bersten, Helen (1993). Coffee floats, tea sinks. Through History and Technology to a Complete Understanding (1 ed.). Sydney / Roseville, Australia: Helian Books. ISBN   0-646-09180-8. (284+4 pages)
  25. U.S. patent 1,370,782 (direct link)
  26. U.S. patent 1,743,925 (direct link)
  27. "Drip-O-lator". OhioRiverPottery.com. Archived from the original on 2007-04-14.
  28. https://www.sampor.de/index.php?id=4938
  29. "Walküre SPM Porzellanfabrik - Made in Germany" [Walküre SPM porcelain manufacturing] (in German and English). Bayreuth, Germany: Walküre Porzellanfabrik  [ de ]. 2017. pp. 8–9, 12–13, 24–25, 116–143, 218–223, 253. Katalog Nr. 58. Archived from the original on 2023-12-28. Retrieved 2023-12-28. (262 pages)
  30. Hack, Markus (2019-01-04). "Geschichte von Walküre: Porzellan vom Bayreuther Festspielhügel" [History of Walküre: Porcelain from Bayreuth's Green Hill]. Wirtschaft. nordbayern.de (Nürnberger Nachrichten) (in German). Nürnberg, Germany: Verlag Nürnberger Presse  [ de ]. Archived from the original on 2023-01-04. Retrieved 2023-12-29.
  31. Gütling, Thorsten (2020-01-08). Bischof, Anja (ed.). "Die Bayreuther Porzellanfabrik Walküre ist Geschichte". BR24 Regionalnachrichten Franken (in German). Bayerischer Rundfunk. Archived from the original on 2020-10-25. Retrieved 2023-06-30.
  32. Schreibelmayer, Stefan (2020-01-07). "Kein Investor - Porzellanfabrik Walküre wird abgewickelt". Wirtschaft. Nordbayerischer Kurier  [ de ] (in German). Bayreuth, Germany: Nordbayerischer Kurier Zeitungsverlag GmbH. Archived from the original on 2023-12-31. Retrieved 2023-12-31.
  33. Schreibelmayer, Stefan (2020-02-09). Written at Bayreuth & Varel, Germany. "Rechte verkauft - Porzellanfabrik: Nur der Name Walküre bleibt" [Rights sold - Porcelain manufacturer: Only the name Walküre remains]. News. Nordbayerischer Kurier  [ de ] (in German). Bayreuth, Germany: Nordbayerischer Kurier Zeitungsverlag GmbH. Archived from the original on 2023-12-29. Retrieved 2023-12-29.
  34. "Walküre Germany / FPM - Katalog" (PDF) (in German). Varel, Germany: Friesland Porzellanfabrik GmbH & Co. KG  [ de ]. 2021-12-01. pp. 30–39. Archived (PDF) from the original on 2023-12-28. Retrieved 2023-12-28. (78 pages)
  35. 1 2 "Preisabbau der weltbekannten Karlsbader Kanne Marke Rosenthal in weißer Ausführung" (in German). Kronach, Germany: Rosenthal. Archived from the original on 2023-01-08. Retrieved 2024-01-01. (4 pages)
  36. "Tassenfilter - Der neue Tassenfilter Marke Rosenthal" [The new cup filter] (in German). Nürnberg, Germany: Rosenthal. Archived from the original on 2023-12-31. Retrieved 2023-12-31. Der Kaffee kommt mit keinem Metall in Berührung, behält daher sein natürliches Aroma. […] Durch Verwendung des doppelt geschlitzten, durchaus glasierten Siebes, kommt das lästige Filtrierpapier, das dem Kaffeearoma schädlich ist, in Fortfall.
  37. Gloess, Alexia N.; Schönbächler, Barbara; Klopprogge, Babette; D'Ambrosio, Lucio; Chatelain, Karin; Bongartz, Annette; Strittmatter, André; Rast, Markus; Yeretzian, Chahan (April 2013) [2012-06-05, 2013-01-08, 2013-01-10, 2013-01-30]. "Comparison of nine common coffee extraction methods: instrumental and sensory analysis" (PDF). European Food Research and Technology  [ d ]. 236 (4). Wädenswil & Zürich, Switzerland: Springer Science+Business Media: 607–627. doi: 10.1007/s00217-013-1917-x . eISSN   1438-2385. ISSN   1438-2377. S2CID   31366362. Archived (PDF) from the original on 2023-12-31. Retrieved 2023-12-31. (21 pages) (Supplemental material)
  38. Velten, Tom (2018). "Historie der Gebrüder Büttnerkaffeeröstereien". Written at Celle, Germany. Im Kalten Krieg. Bankgeflüster: Realitäten nahe gebracht (in German). Vol. 3 (1 ed.). Berlin, Germany: epubli. pp. 30–38. ISBN   978-3-746743-19-6. (251+3 pages)