How do you remove caffeine from coffee?

December 25, 2025 •

3 min read

Decaffeinated coffee often retains a small amount of caffeine; commercial methods typically remove at least 97% of the stimulant from green coffee beans. The commercial processes, conducted before roasting, are more effective than any at-home method.

Quick Summary

Commercial decaffeination removes caffeine from unroasted coffee beans using water, CO2, or chemical solvents. Home methods reduce caffeine, but are less effective. The process used influences the final flavor and quality.

Key Points

Commercial Decaffeination: Most decaf coffee undergoes caffeine removal before roasting using commercial processes like Swiss Water, CO2, and chemical solvents.
No Home Decaffeination: It is not possible to truly decaffeinate coffee beans or grounds at home; DIY methods can only reduce caffeine levels.
Swiss Water Process: This chemical-free method uses water and carbon filters to remove 99.9% of caffeine while best preserving the coffee's original flavor.
CO2 Process: Using highly pressurized carbon dioxide, this method effectively extracts caffeine with minimal flavor alteration, though it is more energy-intensive and expensive.
Solvent Methods: Direct and indirect processes use solvents like ethyl acetate or methylene chloride, which are removed during later stages, but can sometimes affect flavor.
Choosing Decaf: For the best flavor, look for decaf processed with the Swiss Water or CO2 methods, which are often indicated on specialty coffee packaging.

How Coffee is Decaffeinated: An Overview

All decaffeination methods are performed on green, unroasted coffee beans. The beans are steamed or soaked to open pores and increase permeability, aiding caffeine extraction. The most common commercial methods include solvent-based (methylene chloride or ethyl acetate), the Swiss Water Process, and the CO2 Process. The chosen method affects the taste, quality, and cost of the decaf coffee.

Commercial Decaffeination Methods

Swiss Water Process

The Swiss Water Process is a chemical-free method known for preserving flavor. Green coffee beans are soaked in hot water, creating a mixture of caffeine and flavor compounds. This water is filtered through activated charcoal to remove caffeine, producing caffeine-free water. This water is then used to soak a new batch of beans, allowing caffeine to diffuse out while the flavor remains. This process repeats until 99.9% of caffeine is removed.

Carbon Dioxide (CO2) Process

Developed by Kurt Zosel, the CO2 process utilizes pressurized carbon dioxide to extract caffeine. Green beans are soaked and placed in a vessel with supercritical CO2, which dissolves the caffeine. The CO2 is moved to another chamber where the pressure is released, and the caffeine separates. The CO2 is then reused. This method maintains flavor and is used for large batches, despite the expense of the equipment.

Solvent-Based Processes

This is a common and cost-effective method, available in direct and indirect forms:

Direct Method: Beans are steamed and soaked in solvents (methylene chloride or ethyl acetate) that bind to caffeine. Steaming removes solvent residue.
Indirect Method: Beans soak in hot water, transferring caffeine and flavor to the water. The beans are removed, and the water is treated with solvents. The caffeinated solvent is removed by heating, and the flavor-rich water is returned to the beans. Safety regulations ensure minimal solvent residue remains after processing.

Comparison of Decaffeination Methods


Feature	Swiss Water Process	Carbon Dioxide Process	Solvent-Based Method
Chemicals Used	None (100% Chemical-Free)	None (uses CO2)	Methylene Chloride or Ethyl Acetate
Flavor Impact	Minimal, preserves original characteristics	Very little, excellent flavor retention	Can sometimes slightly alter flavor profile
Cost	Premium	High (due to equipment)	Most economical
Best For	Specialty and organic coffee	Large commercial batches	Cost-effective, widely used commercial decaf
Sustainability	High, water and filters are reused	High, CO2 is reused	Varies; Ethyl Acetate can be naturally sourced but is often synthetic

Home Methods for Reducing Caffeine

It is not possible to completely decaffeinate roasted beans or brewed coffee at home. However, you can reduce caffeine content with these methods:

French Press Pre-Brew Method

This two-stage process reduces caffeine:

Use coarse grounds in a French press.
Add hot water to cover grounds and steep for 30-60 seconds.
Plunge slightly to discard the initial, caffeine-rich water.
Add fresh hot water and brew normally.

Soaking Green Beans (Water Process Adaptation)

This method mimics commercial water processes but takes time and may affect flavor:

Soak green beans in water for 8–12 hours.
Simmer in fresh water for 15–20 minutes.
Repeat with fresh water multiple times.
Dry thoroughly and roast. This process can strip flavor and aroma.

Conclusion: Selecting the Right Decaf Coffee

For consumers, the decaffeination method is key to the quality and taste of decaf coffee. Specialty decaf using water or CO2 methods retains more original flavor and is chemical-free. Brands often highlight these methods. Commercial decaf often uses solvent-based methods, which are safe but may result in less nuanced flavor. Understanding these methods helps in choosing based on taste, cost, and process.

Whether buying commercial decaf or trying home methods, remember all decaf contains trace caffeine. Professional processing offers the best flavor and lowest caffeine levels.

Visit the Coffee Review website for an in-depth analysis of different solvent-based decaffeination methods.

Frequently Asked Questions

No, it is not possible to completely decaffeinate coffee beans or brewed coffee at home. Home methods can only reduce the caffeine content, not remove it entirely, and will likely compromise the flavor.

The Swiss Water Process is a patented, 100% chemical-free decaffeination method that uses water and carbon filters to remove 99.9% of the caffeine from green coffee beans while preserving their flavor.

Yes, solvent-based methods, such as those using methylene chloride or ethyl acetate, are considered safe. Any residual solvents are removed during the steaming and high-temperature roasting process.

Decaf coffee can taste different depending on the decaffeination method used. Methods like the Swiss Water and CO2 processes are designed to minimize flavor impact, while solvent methods can sometimes introduce subtle flavor changes.

The CO2 process uses pressurized liquid carbon dioxide to extract caffeine from water-soaked green beans. The CO2 is then separated from the caffeine and reused, resulting in a high-quality, solvent-free decaf.

The additional steps and technology required for the decaffeination process increase production costs, which are then reflected in the final price of decaf coffee.

The Swiss Water Process is widely recognized among specialty coffee roasters as the best method for preserving the coffee's original flavor profile because it is a chemical-free process that focuses on flavor integrity.

No, decaf coffee is not completely caffeine-free. Regulations require that at least 97% of the caffeine be removed, so a small, trace amount remains.