How is Decaf Coffee Made? Decaffeination Explained

Decaf coffee is made by removing caffeine from green (unroasted) coffee beans using one of four methods: the Swiss Water Process, the sugar cane (ethyl acetate) process, the CO2 process, or chemical solvent extraction. Each method removes 97-99.9% of the caffeine while leaving the bean structurally intact so it can be roasted and brewed like regular coffee. Our San Lorenzo Decaf uses the sugar cane process , a natural, chemical-free method that preserves the full flavour profile.

Decaf has a reputation problem, and most of it is deserved , historically. For decades, decaf meant harsh chemical solvents, flavour-stripped beans and a cup that was a thin, hollow approximation of real coffee. That has changed dramatically in the speciality coffee world, where gentler decaffeination methods and higher-quality green beans produce decaf coffees that genuinely rival their full-caffeine counterparts.

This guide explains how each decaffeination method works, the pros and cons of each, and why the method matters for what ends up in your cup.

When Caffeine Is Removed

All decaffeination happens before roasting , on green, unroasted beans. This is important because green beans are more porous and resilient than roasted beans, making it possible to extract the caffeine without destroying the bean's cellular structure. The decaffeinated green beans are then dried, shipped and roasted exactly like regular green coffee.

The challenge of decaffeination is selectivity: caffeine is just one of over 1,000 chemical compounds in a coffee bean. The goal is to remove the caffeine while leaving as many of the flavour compounds , sugars, acids, oils, aromatics , as possible. Different methods achieve this selectivity to different degrees, which is why the decaffeination method has a direct impact on how the coffee tastes.

The Four Decaffeination Methods

1. Swiss Water Process (SWP)

How it works:

1. Green beans are soaked in hot water, which dissolves the caffeine along with many of the flavour compounds (both are water-soluble).
2. The beans are removed and discarded (this first batch is a sacrifice).
3. The caffeine-rich water is passed through activated charcoal filters that are sized to capture caffeine molecules while allowing the smaller flavour molecules to pass through.
4. The result is "Green Coffee Extract" (GCE) , water that is saturated with flavour compounds but free of caffeine.
5. Fresh green beans are then soaked in this GCE. Because the water is already saturated with flavour compounds, only caffeine migrates from the beans into the water (osmosis drives caffeine from high concentration in the bean to low concentration in the GCE, but flavour compounds stay because the water is already full of them).
6. The process is repeated until 99.9% of the caffeine is removed.

Pros:

• 100% chemical-free , uses only water and activated charcoal
• Excellent flavour preservation , widely regarded as one of the best methods for taste
• Certified organic-compatible

Cons:

• More expensive than chemical solvent methods
• Slower process , takes 8-10 hours per batch
• Limited to one commercial facility (Swiss Water Decaffeinated Coffee Company in Burnaby, British Columbia)

2. Sugar Cane Process (Ethyl Acetate / EA)

How it works:

1. Ethyl acetate (EA) is a naturally occurring compound found in many fruits, and it is produced commercially by fermenting sugar cane. The "sugar cane process" name comes from this natural EA source.
2. Green beans are steamed to open their pores and make the caffeine more accessible.
3. The beans are repeatedly washed with an EA solution. Ethyl acetate bonds with the caffeine molecules and carries them out of the bean.
4. The beans are steamed again to remove any residual EA.
5. The beans are dried to their original moisture content, ready for roasting.

This is the method used for our San Lorenzo Decaf. The sugar cane process is particularly well-suited to Colombian coffees because the EA is produced locally from Colombian sugar cane, and the decaffeination can be done close to the farm , reducing transport and maintaining freshness.

Pros:

• Naturally derived solvent from sugar cane fermentation
• Excellent flavour preservation , often praised for maintaining body and sweetness
• Faster and less expensive than Swiss Water
• Well-established in Colombian coffee production

Cons:

• Although EA is naturally derived, it is technically a solvent , some consumers prefer the "water only" approach of SWP
• Residual EA is removed by steaming, but trace amounts may remain (well below any safety threshold, and EA evaporates completely during roasting at 180°C+)

3. CO2 Process (Supercritical Carbon Dioxide)

How it works:

1. Green beans are soaked in water to expand them.
2. The beans are placed in a sealed extraction vessel.
3. Liquid CO2 is pumped through the vessel at very high pressure (approximately 73-300 atmospheres). At this pressure, CO2 becomes "supercritical" , it has the penetrating properties of a gas but the dissolving properties of a liquid.
4. The supercritical CO2 selectively dissolves the caffeine while leaving the larger flavour molecules intact.
5. The caffeine-laden CO2 is moved to a separate chamber, where the pressure is released. The CO2 returns to gas form, and the caffeine precipitates out. The CO2 is recaptured and reused.

Pros:

• Excellent selectivity . CO2 is very good at targeting caffeine specifically
• Chemical-free (CO2 is naturally occurring and food-safe)
• Produces some of the cleanest-tasting decaf available
• CO2 is recyclable , environmentally efficient

Cons:

• The most expensive method due to the specialised high-pressure equipment required
• Typically used for large-volume commercial operations rather than small speciality lots
• Limited availability for single-origin speciality coffee

4. Chemical Solvent Process (Methylene Chloride / MC)

How it works:

1. Green beans are steamed to open pores.
2. The beans are repeatedly rinsed with methylene chloride (MC), which bonds with and extracts the caffeine.
3. The solvent is drained away, and the beans are steamed again to remove residual MC.
4. The beans are dried and prepared for export.

This is the oldest and cheapest decaffeination method. It is sometimes called the "European process" or "traditional process."

Pros:

• Cheapest method , widely used for commodity-grade decaf
• Fast and efficient at scale
• FDA and EFSA approved , residual solvent levels are well below safety thresholds (the EU limit is 2mg/kg; most MC-processed decaf contains less than 1mg/kg, and roasting at 180°C+ evaporates virtually all residual solvent)

Cons:

• Uses a chemical solvent , methylene chloride is a chlorinated compound. Although residual levels are considered safe, many consumers prefer to avoid chemical solvents entirely.
• Flavour impact . MC decaffeination tends to strip more flavour compounds along with the caffeine, producing a flatter, less complex cup than SWP, sugar cane or CO2 methods
• The method most associated with "bad decaf" historically

Which Method Does We Are Coffee Co Use?

Our San Lorenzo Decaf is decaffeinated using the sugar cane (ethyl acetate) process. We chose this method for several reasons:

• The EA is naturally derived from Colombian sugar cane , aligning with our commitment to natural, traceable sourcing
• The process preserves the full body and sweetness of the Colombian San Lorenzo lot
• Decaffeination happens close to the farm in Colombia, maintaining the connection between farm, process and cup
• The result is a coffee that tastes like coffee , full-bodied, sweet, complex , not a hollow approximation

The San Lorenzo has the highest repeat purchase rate of any coffee in our range. That single data point tells you everything about whether the sugar cane process preserves flavour quality.

Does Decaffeination Affect Taste?

Honestly , yes, to some degree. Even the best decaffeination methods remove some flavour compounds along with the caffeine. The difference is how much.

Chemical solvent methods (MC) tend to strip the most flavour, producing a noticeably flatter cup. Swiss Water and sugar cane processes preserve significantly more complexity, body and sweetness. CO2 processing produces exceptionally clean results but is rare in the speciality market due to cost.

The quality of the green beans matters enormously. A speciality-grade lot decaffeinated with a gentle method (like our San Lorenzo) will taste dramatically better than a commodity-grade lot processed with MC , because it started with far more flavour to preserve.

Is Decaf Coffee Healthy?

Decaf coffee retains most of the health-associated compounds found in regular coffee , antioxidants, chlorogenic acids, and polyphenols. Research suggests that many of coffee's health benefits (reduced risk of type 2 diabetes, liver disease, and certain cancers) are associated with these compounds rather than with caffeine itself.

Decaf is a sensible choice for people who are caffeine-sensitive, pregnant (NHS guidance recommends limiting caffeine to 200mg/day during pregnancy), experiencing anxiety or sleep issues, or simply want to enjoy coffee later in the day without affecting sleep quality.

The residual solvent concern (for MC-processed decaf) is not considered a health risk at the trace levels present in finished coffee , but if it concerns you, choose SWP, sugar cane or CO2-processed decaf, which use no chemical solvents.

Frequently Asked Questions

Try Decaf That Tastes Like Coffee

If your experience of decaf has been limited to flat, flavourless commodity coffee, our San Lorenzo Decaf will change your expectations. Sugar cane processed, Colombian single origin, full-bodied, sweet and complex. Browse our full decaf range for all available options.

All our coffees are flame-roasted in small batches in Glasgow, SCA-scored to speciality grade, and dispatched within days of roasting. Free delivery on orders over £25.