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Decaf coffee: processing methods explained

Caffeine – or C8H10N4O2 trimethylxanthine if we’re referring to its technical name – is a naturally-occurring stimulant. Caffeine can be found in coffee, tea, guarana and cacao beans and is used as an additive in food and drink products such as soda, energy drinks and supplements. Arguably though, caffeine is most associated with coffee (even the names sound the same), and an average ‘cup’ (a standard measuring cup – or ½ pint) contains between 70-140mg. To put this into perspective, the Association of UK Dieticians suggests 300mg of caffeine per day (or less in certain circumstances) based on advice from health organisations around the world.

Why is it in our coffee?

It’s thought that the coffee plant contains caffeine as a means of self-protection, because it acts as a natural pesticide to protect the plant as it grows in certain regions. So, in its natural form, coffee will contain caffeine. Well, most of it. There is such a big range in the caffeine content (above) as the caffeine content can be dependent on a variety of factors – for example, Robusta coffee beans contain almost twice as much caffeine as Arabica.

Over the years, scientists have discovered coffee plants that do not contain caffeine. During the late 20th century, various studies were conducted on tens of thousands of genetic strains of the coffee plant to see if a natural cup of decaffeinated coffee could be produced. And, by the early 2000s, a handful of coffee plants had been identified that lacked the enzyme needed to produce the stimulant so many of us love in a mug. From here, attempts were made to either make a batch of coffee from beans as they were or use the scientific profile of the plants to genetically modify new caffeine-free coffee beans.

However, most of the ‘decaffeinated’ coffee we drink is not naturally caffeine free, to cut a long story short; the caffeine is removed through one of the processes below

How do we remove the caffeine from our coffee?

At Lincoln & York, we buy five different types of decaffeinated coffee. The origin of the coffee bean and the method used to remove the caffeine affects both the taste and the price.

MC or Methylene Chloride

The MC method can be done in two ways – direct or indirect. Direct solvent extraction means the beans are steamed, soaked in solvent to remove caffeine, then steamed again, dried and roasted. For indirect solvent extraction, beans are soaked in hot water, before the water is mixed with the solvent to remove caffeine, flavours in the water are then returned to the beans.

Mountain water extraction

As the name suggests, this method uses the process of water extraction on green coffee beans through saturation and filtration, where caffeine is removed then the flavourful water is put back into the coffee with just 0.1% caffeine remaining.

The Swiss water process

This process uses the chemistry of pure water to remove water solubles from green coffee extract (GCE). Given that caffeine isn’t a water soluble, this causes the caffeine to ‘migrate’ – known as diffusion – from the green coffee, which can then be carbon filtered out of the solution. The now caffeine-free GCE is then returned to the coffee.

The EA (or Sugarcane method)

This method is a natural process which uses Ethyl Acetate (EA) to remove the caffeine from the bean. As EA occurs in many fruits as a naturally occurring substance, this method is often referred to as “natural decaffeination”. To remove the caffeine from the bean, the coffee bean is steamed until they swell before being immersed in a solution of water and EA to “wash” the beans. This method can also be referred to as the “Sugarcane method” as at origin, EA is often derived from fermented Sugarcane grown nearby.

The carbon dioxide method

Last but not least, the carbon dioxide (CO2) method. This method places soaked beans into an extraction vessel before CO2 is passed through; taking the caffeine with it. In the absorption vessel, caffeine is syphoned away with water and the CO2 goes back to the extraction vessel. The recent CO2 shortage has made this process more expensive.

To ‘caff’ or to decaf, that is the question…

At Lincoln & York we believe the quality of decaf has improved greatly over the past few years. Our coffee team and qualified Q graders say “Historically there was a noticeable taste difference between decaf coffee and standard caffeinated beans, however thanks to developments in the extraction processes this isn’t always the case.

“Anyone thinking of cutting back on caffeine doesn’t have to compromise on taste. Some coffee drinkers may have tried decaf before, not enjoyed the flavour and been put off, however, we’re now seeing some brilliant examples of delicious decaf coffees that rival their caffeinated counterparts. The main point to take home is that coffee lovers don’t have to choose between one or the other; whether you divide it between AM and PM, weekday and weekend there is room for both options.  

“We understand that coffee can be part of a ritual for most people. Making up part of their morning (or bedtime) routine, after dinner or for a friendly meet-up in their local coffee shop. A good decaf coffee can fit seamlessly into any of these events. Available as beans for coffee machines, ground coffee for cafetieres or coffee bags for coffee on the go, nowadays instant is far from the only option when it comes to decaf.”

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