How decaf coffee is made
Caffeine is removed while the beans are still green, so the roaster never sees it.
- stations
- 7
- things upstream
- 10
- raw sources
- 7
- steps from the ground
- 4
The short version
Decaffeination happens before roasting. Green beans are steamed, then washed with water, a liquid solvent, or pressurized carbon dioxide until most of the caffeine has dissolved away. The beans are dried and then roasted as usual. In the US, at least 97% of the caffeine must be removed before the coffee can be called decaffeinated.
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Steam the green beans
Hard, dry green beans are steamed to open their pores. Caffeine is trapped deep inside the bean, and it will not escape until the bean is swollen and wet.
Goes in -
Soak in hot water
In the indirect solvent and Swiss Water routes, the beans are first soaked in hot water for several hours. The water pulls out caffeine and many other flavor compounds.
Goes in -
Pull the caffeine out
Caffeine is removed from the beans or from the soaking water using a liquid solvent such as ethyl acetate, an activated charcoal filter, or high-pressure carbon dioxide. Caffeine dissolves into the carrier, while the flavor compounds mostly stay put.
300 atm and 65 °C for supercritical CO2
Goes in -
Repeat until almost gone
Solvent routes run the cycle over and over. Each pass leaves less caffeine in the bean until the batch tests clean.
8 to 12 rinses
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Steam off the carrier
Beans are steamed again to drive off leftover solvent, then dried back to normal moisture. They are brownish gray and still unroasted.
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Test the caffeine left
Labs measure the residual caffeine with liquid chromatography or near-infrared spectroscopy. A batch that misses the standard goes round again.
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Roast like any other
From here the beans are roasted, cooled and ground just like regular coffee. Roasting does not remove caffeine, which survives up to around 200 °C.
Worth repeating
- The first commercial decaffeination process was invented by Ludwig Roselius in 1903 after a shipment of beans soaked in seawater lost most of its caffeine.
- A 2006 study found decaffeinated drinks typically contained 1 to 2% of the original caffeine content.
- One study found that fourteen to twenty cups of shop-bought decaf would hold as much caffeine as one regular cup.
- A naturally caffeine-free coffee plant, Coffea charrieriana, was reported in 2004.
Back to the ground
Follow every input upstream and decaf coffee starts as these 7 raw sources.
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Sources
Cite this page: "How decaf coffee is made." Assembly Line, 2026-11-03. https://assemblyline.org/make/decaf-coffee