Cold brew

History

Cold is nothing new. In 1922, Ukers already describes Brazilians who let coffee soak in cold water for several hours, filter it, then reheat the liquid as needed, and Cubans who pour cold water over a flannel bag until they obtain a very concentrated extract (source 1). The same book reports, in the cautious form of “it is said,” the Algerian origin of the mazagran: sweetened coffee, diluted with water or ice, that French colonial troops supposedly drank near the fort of Mazagran before bringing it back to the cafés of Paris, served in a tall glass (source 1). The mazagran is a coffee prepared and then diluted cold, not a cold extraction; it only shows that cold coffee already had its place at the counter.

Commercial cold-infused coffee, the kind English calls cold brew, was born from a brand. The maker Toddy traces its history to 1963: a trip in the mountains of Peru, a cold-brewed coffee served hot, and Todd Simpson trying to reproduce it; the system reached the United States “a few years and a patent later” (source 2). The patents found are two design patents, which protect a shape and not a process, in the name of Oscar S. Simpson Jr. of Houston: the first, filed in February 1966, was issued in July 1967; the second, issued in 1973, was assigned to Toddy Products Inc., in Houston (sources 3 and 4). That Oscar S. Simpson Jr. is the “Todd” of the brand is deduced from this assignment; no source read says so in so many words.

Science arrived late. In 2018, Rao and Fuller found only four published, peer-reviewed studies on cold brew, none complete enough to confirm or refute what sellers say about it (source 6).

Selling in bottles raised a question that home brewing ignores. In the United States, a hermetically packaged cold-brewed coffee falls, according to the National Coffee Association, under the federal rules on low-acid canned foods; in 2024, a manufacturer that had not declared its process to the federal agency recalled all its cans, with no illness reported (source 10).

The motion

The grounds and the water are mixed in a closed container, left to rest, then filtered. The manufacturer speaks of 8 to 24 hours of soaking and of a concentrate that keeps more than a week in the refrigerator (source 2). The protocol of the chemists of Thomas Jefferson University, in Philadelphia, is simpler still: 35 g of coffee in 350 mL of filtered water, in a screw-top jar, the grounds held in a mesh bag to stay submerged (source 5).

It is an immersion: all the water is in contact with all the coffee, and concentration rises up to a plateau. Fuller and Rao measure this plateau between 6 and 7 hours for caffeine and 3-chlorogenic acid, and not between 10 and 24 hours as common recipes say (source 5). Beyond that, time extracts almost nothing more of these two compounds.

The settings

• Grindcoarse in practice; in Fuller and Rao's tests, the grind did not significantly change the caffeine or 3-chlorogenic acid extracted cold (source 5)
• Dose35 g of coffee for 350 mL of water in the Philadelphia protocol (source 5)
• Brew ratio1:10 in this protocol (source 5); the commercial concentrate is then diluted to taste (source 2)
• Temperatureroom temperature, 20 to 25 °C or less (source 5); 4 °C and 22 °C in Davis's tests (source 7)
• Time8 to 24 h according to the manufacturer (source 2); plateau reached in 6 to 7 h for caffeine and 3-chlorogenic acid (source 5)
• Pressurenot applicable: atmospheric pressure

What it has going for it

• The concentrate is prepared in advance and in volume, then served cold or hot, diluted to each person's taste (source 2).
• At equal concentration and served at the same temperature, the brew made at 4 or 22 °C is judged less bitter and less sour than the same brew made at 92 °C, and more floral (source 7).
• The method is forgiving: past the plateau of 6 to 7 hours, one more hour changes almost nothing in the caffeine or 3-chlorogenic acid extracted (source 5).

What is held against it

• It has to be started hours ahead, where a hot filter takes a few minutes (source 2).
• Fewer acids come through: titratable acidity, that is, the total quantity of acids that can be neutralized in the laboratory, is lower than when hot, which softens the liveliness of the coffees chosen precisely for it (source 6).
• The argument of a coffee that is “gentle on the stomach” does not rest on pH, which stays the same as when hot, between 4.85 and 5.13 in Rao and Fuller's measurements (source 6).
• No hot step sanitizes the liquid: sold in cans, it must follow in the United States a declared low-acid canned food process (source 10).
• The cup may contain more caffeine than one thinks: with a coarse grind, Fuller and Rao measure markedly more than in a hot brew (source 5).

What it gives in the cup

The cleanest comparison comes from Davis. The same coffee, of three origins and three roasts, is brewed at 4, 22 and 92 °C to equilibrium, then diluted to exactly 2% of dissolved solids and served at 4 °C for all. Four attributes change with brewing temperature whatever the origin and roast level: bitterness, sourness and a rubbery note are stronger when hot, floral stronger when cold. The rest depends heavily on the coffee (source 7).

Acidity takes two figures. The pH, which counts only the acids active at the moment of reading, is the same cold and hot; titratable acidity, which counts all the acids present, is lower cold, as is antioxidant activity (source 6). In Bogota, the cold immersion brew comes out sweet, with notes of hazelnut, caramel and malt, and contains less of certain furanic compounds than the hot brew (source 8). The color changes too: cold brews tend toward red, hot ones toward black (source 9).

Cold is not a world apart. Following brewing over time, the Davis team finds that some long cold brews have a profile close to that of some short hot brews (source 11).

Anecdotes

The sources for this sheet

1. William H. Ukers, All About Coffee, New York, 1922, ch. XXXV (customs of Brazil, Cuba, Algeria and France) · online · secondary
2. Toddy LLC, “The Toddy story” and “What is cold brew,” toddycafe.com, accessed October 21, 2026 · online · manufacturer
3. Oscar S. Simpson Jr., design patent US D208,032, “Coffee maker,” filed February 2, 1966, issued July 4, 1967 · online · primary
4. Oscar Strother Simpson Jr., design patent US D229,530, “Coffee maker,” assigned to Toddy Products Inc., Houston, filed November 11, 1971, issued December 11, 1973 · online · primary
5. Megan Fuller and Niny Z. Rao, “The Effect of Time, Roasting Temperature, and Grind Size on Caffeine and Chlorogenic Acid Concentrations in Cold Brew Coffee,” Scientific Reports, 7, 17979, 2017 · online · primary
6. Niny Z. Rao and Megan Fuller, “Acidity and Antioxidant Activity of Cold Brew Coffee,” Scientific Reports, 8, 16030, 2018 · online · primary
7. M. E. Batali et al., “Sensory Analysis of Full Immersion Coffee: Cold Brew Is More Floral, and Less Bitter, Sour, and Rubbery Than Hot Brew,” Foods, 11 (16), 2440, 2022 · online · primary · reading: article abstract
8. N. Córdoba et al., “Chemical and sensory evaluation of cold brew coffees using different roasting profiles and brewing methods,” Food Research International, 141, 110141, 2021 · online · primary · reading: article abstract
9. S. E. Yeager et al., “Roast level and brew temperature significantly affect the color of brewed coffee,” Journal of Food Science, 87 (4), 1837-1850, 2022 · online · primary · reading: article abstract
10. Nick Brown, “Snapchill Recalls All Cold Brew Cans Due to Toxic Growth Risk,” Daily Coffee News, June 19, 2024 · online · press
11. J. Liang et al., “Sensory analysis of the flavor profile of full immersion hot, room temperature, and cold brewed coffee over time,” Scientific Reports, 14, 19298, 2024 · online · primary · reading: article abstract