Exploring the CO2 Decaffeination Process in Speciality Coffee

Exploring the CO2 Decaffeination Process in Speciality Coffee

In the world of speciality coffee, every step of the journey matters, from bean to cup. But what about decaffeinated coffee? Often relegated to the sidelines, decaf coffee has long suffered from a reputation of inferior taste compared to its caffeinated counterparts. However, the emergence of speciality decaf, especially those processed using CO2, is changing the game. 

Let's take a deep dive into the CO2 decaffeination process.

Understanding Decaffeination

Firstly, we need to understand decaffeination. It is often referred to simply as decaf, and is the process of removing caffeine from coffee beans. This process is mainly done to produce coffee that contains nearly no caffeine. 

Decaffeination is the process of removing caffeine from coffee beans while preserving the flavour compounds that contribute to its taste profile. There are several different methods to use to decaffeinate the coffee - using organic chemical compounds such as methylene chloride or ethyl acetate, or using liquified CO2, or simply water (Swiss Water method). 

The methods vary in their effectiveness, impact on flavour, and environmental footprint. Speciality coffee producers often opt for methods that preserve the flavour profile of the beans while minimising chemical residues and environmental impact. The choice of decaffeination method can significantly influence the quality and characteristics of the final decaffeinated coffee, making it an important factor for both producers and coffee drinkers.

The CO2 Decaffeination Process

The CO2 method, also known as supercritical fluid extraction, has been recognised for its effectiveness and minimal impact on coffee's taste profile. It is also one of the most environmentally friendly decaffeination methods in the speciality coffee industry. 

This process was first discovered in 1967 by scientist Kurt Zosel at the Max Planck Institute for Coal Research, as he was looking at new ways of separating mixtures of substances. Zosel experimented with different methods for decaffeinating coffee and discovered that CO2 in its supercritical state could selectively extract caffeine from coffee beans while leaving other compounds largely intact.

Here's how it works:

  1. Pre-Soaking: Green, unroasted coffee beans are soaked in water or steamed for up to 30 minutes to open their pores, making it easier for caffeine extraction.
  2. Pressurisation: The beans are then placed in a sealed stainless steel vessel and a mixture of water and CO2 gas (essentially carbonated water) is pumped into the vessel. The pressure inside the vessel rises up to 300 times the normal atmospheric pressure. Under these conditions CO2 turns into a substance that is neither gas nor a liquid. And that’s where the magic happens.
  3. Caffeine extraction: As the CO2 interacts with the beans, it selectively removes caffeine while leaving other flavour compounds intact. The caffeine-filled CO2 is then circulated through an activated charcoal filter, which traps the caffeine molecules.
  4. Depressurisation: The pressure in the vessel is released, allowing the CO2 to return to its gas state
  5. Drying: The decaffeinated beans are then dried to reduce the moisture down to 9-12%  before being shipped to the roasters.

Advantages of CO2 Decaffeination

Overall, CO2 decaffeination offers a range of advantages that make it an attractive option for speciality coffee producers and consumers seeking high-quality decaffeinated coffee. From its chemical-free process and preservation of flavour profiles to its sustainability factors and versatility, CO2 decaffeination continues to be a preferred method for decaffeinating coffee beans in the speciality coffee industry.

Some of the benefits are:

  1. No Chemical residue: Unlike solvent-based methods, the CO2 process leaves behind no chemical residue, ensuring a cleaner, more natural cup of decaf coffee.
  2. Preserving flavour: CO2 decaffeination is known for retaining the characteristics of the original coffee beans, which gives a more flavorful decaf experience.
  3. Environmentally friendly: CO2 is a naturally occurring compound that is recycled and reused in the decaffeination process, making it a sustainable option.
  4. Versatility: The CO2 method can be used on a wide range of coffee beans without compromising their flavour profiles, making it suitable for speciality coffee varieties.

Speciality Coffee and CO2 Decaf

Speciality coffee is all about quality, flavour, and sustainability. With the rise of speciality decaf, there's a growing demand for decaffeinated coffee that meets the high standards set by the speciality coffee industry and considered consumers. CO2 decaffeination aligns perfectly with these principles, offering a decaf option that doesn't sacrifice taste or quality.

One of the key reasons speciality coffee roasters are turning to CO2 decaf is its ability to preserve the unique flavour profiles of different coffee origins. Whether it's a fruity Ethiopian or a rich Colombian, CO2 decaffeination allows roasters to offer decaf versions without compromising on taste.

Challenges and Considerations

While CO2 decaffeination offers many benefits, it's not without its challenges. The process can be more expensive and time-consuming compared to solvent-based methods, which may result in slightly higher prices. Additionally, the equipment required for CO2 decaffeination can be costly to install and maintain, making it less accessible to smaller coffee producers.

There's also the issue of scalability. While CO2 decaffeination is well-suited to smaller batches of speciality coffee, scaling up production to meet higher demand can be a challenge. As the popularity of speciality decaf continues to grow, finding ways to increase production capacity without compromising on quality will be essential.

The Future of CO2 Decaf in Speciality Coffee

CO2 decaffeination represents a significant step forward for speciality coffee, offering a cleaner, more flavourful alternative to traditional decaf methods. As the speciality decaf market continues to expand, CO2 decaf is poised to play an increasingly prominent role, satisfying the cravings of coffee lovers who want all the flavour without the caffeine buzz.


If you’re looking for a speciality decaf coffee, try Sans. It’s a great Peruvian coffee with tasting notes of dark chocolate, red apple and toasted almonds. 

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