Methylene Chloride solvent decaffeination is the old fashioned way to decaffeinate coffee and it's still how the vast majority of coffee is decaffeinated globally.
Broadly speaking, Methylene Chloride is a solvent used in both methods of direct decaffeination and is thought by some in the coffee industry to maintain coffee flavour more reliably than other processes.
Indeed, when you drink decaffeinated instant coffee, it will almost certainly be decaffeinated using the Methylene Chloride solvent process.
Likewise, if there's no mention of how the roast coffee was decaffeinated on the packet, again, it's almost certain to be MCP.
But what is the Methylene Chloride decaffeination process all about?
In scientific terms, Methylene Chloride is a colourless chemical solvent in liquid form with a slightly sweet aroma with a boiling point of 104°F. It is a chemical solvent with multiple uses including paint remover and hair spray.
The U.S. Food and Drug Administration (FDA) has determined that Methylene Chloride decaf is safe for use in coffee decaffeination and FDA regulation allows for up to 10 parts per million (ppm) of residual methylene chloride in decaffeinated coffee.
The method of Methylene Chloride solvent decaffeination is as follows:
First, the coffee beans are treated with steam to draw the caffeine from the inner coffee bean to the outer surface area of the bean.
Methylene Chloride is applied directly to the beans. As a chemical solvent, MC removes the caffeine.
Then steam is applied to the coffee beans again to drive out residual solvent.
Finally, the beans are dried and roasted, which removes any further residues of the chemical solvent.
Any amounts of methylene chloride left in brewed coffee would be less than one part per million.
How does Methylene Chloride decaf compare with Swiss Water Process in terms of caffeine levels?
Methylene Chloride decaffeination removes between 96 and 97 percent of caffeine from a batch of coffee.
Swiss Water Decaf Process is certified 99.9% caffeine free.
A major new Study found Methylene Chloride traces in major decaf coffee brands
The Clean Label Project’s mission to analyse & raise awareness of chemicals in everyday consumer products.
As part of this, Clean Label Project (CLP) analysed dozens of well-known decaffeinated coffee brands to see if Methylene Chloride (a powerful solvent and the active ingredient in paint stripper) was present in these decaf coffee brands.
It is important to note that this was a test on American coffee brands in the United States - not on European coffee brands in Europe.
So, how were the coffee brand samples tested?
CLP used an accredited analytical chemistry laboratory to blind test a large range of decaffeinated roast coffee brands in the USA (not Europe).
The decaf coffee samples were then sampled into tubes and numbered (with the number corresponding to CLP records to keep impartiality).
Now for the “science”…!
- The standards and samples were prepared for analysis using the following approach:
- An internal standard solution containing chloroform and fluorobenzene were purchased at a working concentration.
- A stock standard solution of methylene chloride was also purchased at a working concentration.
- The standard stock solution was spiked into 5mL of water at various levels with the internal standard being added at the same level throughout the calibration range.
- The calibration curve was analysed by Gas Chromatography Mass Spectroscopy with Purge and Trap.
- The samples were prepared by adding 0.5grams of ground coffee to a vial, along with 5ml of water, stir bar, and internal standard. The level of quanti‑cation was 50 parts per billion (ppb).
So, what were the results?
It’s best to review the results properly here at:
But see the main summary below: