Decaf explored: What is the CO2 Process?

Friday, 10 May, 2024

Words by Katie Burnett

Love it or hate it, decaf plays an important role in the coffee industry. “Death before decaf” is a well-known sentiment amongst die-hard caffeine fiends. Ordering a decaf at an average café often sends you reaching for the sweeteners. This is also often because decaf beans are trickier to roast and have traditionally been presented as a super dark roast. But there are good decaf coffees out there! Promise!

The 2024 US Brewer’s Cup winner, Weihong Zhang, won using a decaffeinated typica from Colombia. This coffee was not a CO2  processed decaf, but rather decaffeinated using a combination of water and an ethyl acetate solvent. However, this win places a spotlight on decaf coffee and it’s important place in specialty coffee as well as illustrate the increasing flavour potential of decaf coffee.

Caffeine naturally occurs in coffee plants as an insect repellent. Caffeine is toxic to most pests and so coffee plants naturally produce caffeine as a means of protecting itself. 

How does decaf become decaf? Well, there are lots of ways that coffee can be processed to create a decaf coffee. Decaffeination occurs by removing the caffeine from a normal coffee bean, by various methods. There are also a couple of rare coffee varietals that produce extremely low amounts of caffeine and could be classified as low-caffeine coffee naturally (such as Coffea Lancifolia from Madagascar, Coffea Racemosa from South Africa and Zimbabwe, Arabica Laurina from Central America and Brazil). However, most decaf options on the market have been synthetically decaffeinated. 

One of the most popular decaffeination processes in specialty coffee is the CO2 process. One of the concerns with decaffeination is the loss of flavour and body in the coffee, which many of us can attest to. CO2 processing is known to be the least invasive to the flavour molecules of the beans and is chemical-free. 

To begin the CO2 process, the coffee is submerged in water and the water-soaked beans placed are then placed in a container. Liquid carbon dioxide is then flushed into the container at a high pressure (1000 pounds per square inch). The carbon dioxide dissolves and draws the caffeine from the bean without affecting the larger flavour and structure molecules. The caffeine infused CO2 is then transferred to another container and the pressure is released for the CO2 to return to a gaseous state.

Handy diagram by The Coffee Quest!

The process is done with all-natural gases and is completely organic. The caffeine that is extracted is then captured and reused in caffeine-infused products. The CO2 process removes around 99% of the caffeine in the coffee. 

Decaf coffee, after processing and drying and before roasting, does not have the vibrant green colour of regular green coffee. It is slightly duller and browner and is a bit trickier to roast. The decaf is not as stable in the drum of the roaster as regular coffee and can be difficult for a roaster to monitor accurately. Additionally, those who use the colour of the beans to monitor their roast, face an additional challenge of completely different colouring to regular coffee.

Caffeine plays a massive role in the coffee industry. That early-morning wake up and late-afternoon slump keeps the industry wheel spinning, but as consumers of the 21st century become more aware of the health effects of excessive caffeine, decaf is an important part of the future of coffee. Decaf is often overlooked by café owners as it forms such a tiny part of their revenue, but with the increasing potential of decaf coffee, it is an undeniable opportunity to invest in a diverse customer base. 

More flavourful decaf options are an opportunity for inclusivity in the specialty coffee industry. The CO2 processing method allows for a decaf option that is organic and chemical-free, so our caffeine-averse friends don’t need to face additional chemicals and toxins with their decaf coffee.

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