What Does Decaffeinated Really Mean?
Many people enjoy coffee for its caffeine properties as well as its rich flavours. There are, however, times when decaffeinated coffee is required; sometimes for health purposes, or because you want to avoid caffeine late at night. Luckily, ‘no caffeine’ doesn’t mean you have to sacrifice the taste and there are various options available to you.
Decaffeinated or Caffeine-free:
The terms decaffeinated and caffeine-free are often used interchangeably but they are, in fact, different things.
Decaffeinated refers to a product that has deliberately gone through a process to remove most of its caffeine.
Caffeine free however, means that in its natural state, the ingredients do not contain any caffeine.
There is no such thing as caffeine-free coffee, so for the caffeine levels to be reduced, it will have to go through a process. Notice that these processes will only reduce caffeine, they cannot completely remove it. If you come across a coffee that claims to be caffeine-free it is likely that it is actually decaf (or less commonly, it is an alternative drink that has been made with herbs and flavouring to make it taste like coffee). For a drink to comply with the decaffeinated label, it has to be 97% free from caffeine.
Methods of Decaffeination
There are various methods used to create decaf coffee; each will leave you with differing levels of caffeine in the end.
There are four common methods typically used; two are solvent-based and two are non-solvent based.
Solvent-based processes use a chemical solvent, like ethyl acetate or methylene chloride to remove caffeine from the beans.
In the direct method, the beans are steamed for approximately 30 minutes, opening their pores, and then the solvent is applied directly to the beans, usually by soaking them in a container. This soaking will take up to 10 hours. The beans then get steamed once more to ensure any residue is removed, and then they are dried and roasted as normal. This will remove around 97% of the caffeine. This method is sometimes called the Natural Decaffeination Method.
While the flavour of all decaffeinated coffees will not be identical to regular coffee, the direct-solvent method, and the Swiss Water Process, outlined below, allow the decaf to maintain the majority of the flavours of a fully-caffeinated version.
This method still uses methylene chloride as a solvent, but this doesn’t actually touch the beans. Instead, the beans are soaked in hot, almost boiling water for a few hours and then transferred to a container with the chemical. As the solvent bonds with the caffeine it floats to the top of the water, where it can be skimmed and removed. The water, which now only has traces of caffeine in, is placed back over the beans, where they reabsorb it. This process is carried out several times until it has removed 95-97% of caffeine.
Decaffeination methods that use solvents are most common as they are low cost and effective, and the indirect process is often preferred as the beans do not come into contact with any chemicals.
The Carbon Dioxide Process
This is known as the CO2 method, or liquid carbon dioxide method.
This method is one of the newest developments when it comes to decaffeination, and uses the same principles of solvent methods, but with CO2 instead of chemicals.
Here, coffee beans are first soaked in water and then placed in a stainless steel tank or container, known as an extraction vessel or extractor. This is sealed, and liquid CO2 is blasted into the coffee at a pressure of around 1000lbs per square inch. This force allows the CO2 to dissolve and extract the caffeine from the beans, without damaging or removing any flavour molecules.
The CO2 gas, which is now full of caffeine is moved to an absorption tank, where its pressure is released, returning CO2 to its natural gas state. Through a charcoal filter, the gas and caffeine are separated. The gas can then be re-used and the caffeine is often used in supplements.
This method can remove anywhere between 95% and 99% of caffeine.
As this process is quite costly, it is generally only used when there are large quantities of beans and is most commonly used on commercial-grade coffees, such as those that you would find in a supermarket.
The Swiss Water Process
Swiss Water Decaf Coffee Swiss Water Process is also known as activated charcoal decaffeination or abbreviated as the SWP Method.
This is a chemical free method that, unsurprisingly, was created in Switzerland almost 100 years ago.
This process uses activated charcoal plus osmosis to achieve decaffeination, instead of solvents or chemicals.
Unroasted coffee beans are boiled in hot water which will start the process of dissolving the caffeine. This will remove caffeine, oils, flavours and other nutrients from the beans, leaving them sitting in the water which is referred to as Green Coffee Extract. This Green Coffee Extract is then passed through an activated charcoal filter. The filter is designed so that it can catch caffeine molecules due to their larger size, but allows other smaller molecules to run through.
Once this first filtration has been completed, you will be left with flavourless beans which are of no use, so are discarded, however the container of filtered, flavoured water is kept.
This water will be used again to remove caffeine from a fresh supply of beans, in the same way as it was used for the first set of beans. The difference here is that the water is already saturated with flavours so the matching flavour molecules from the new beans will not diffuse. Only the caffeine molecules are able to flow from the beans to the water.
Thanks to the osmosis principles, the second batch of beans keep most of their flavour, but their caffeine is almost completely removed.
The Swiss Water Process is very popular as it is environmentally friendly, chemical-free and can remove between 99 and 99.9% of caffeine. Unlike the other methods, the extracted and filtered coffee cannot be sold to other companies or used in supplements.