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Coffee Without Caffeine | Greg Foot | Earth Lab

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What are the techniques to get the caffeine out of coffee and get a decaf? Greg Foot illustrates the four options.

Coffee it’s the second most popular drink in the world after tea of course who can resist that alluring rich bitterness and that caffeine kick that drags you into the world of the living each morning well me actually i haven’t had a caffeinated coffee or a caffeinated tea for over four years now possibly five i’ve lost count but the thing is hmm i love the taste

Of coffee so i drink quite a few cups of decaffeinated joe and i thought it was about time i did a video answering my own question of just how do we get the caffeine out caffeine is a stimulant a psychoactive drug that affects the nerves in your brain the story of its effects starts with adenosine a neuromodulator created in the brain adenosine binds to specific

Receptors aptly named adenosine receptors and that binding actually slows down nerve cell activity which makes you feel drowsy it turns out that caffeine is a ninja molecule that can also sneak in and bind to that same adenosine receptor if there’s a lot of caffeine then they fill up all those receptors when adenosine has nowhere to bind the nerves don’t slow down

Like they with normally and you don’t get drowsy in fact your nerve signals actually speed up your pituitary glands senses this gear shift think that something bad is happening goes into fight-or-flight mode by releasing hormones that tell your adrenal glands to produce epinephrine adrenaline that leads to the heart rate increase the tensed muscles in the pupil

Dilation you get sometimes for a particularly strong cup of java interestingly caffeine also ups your dopamine levels which gives you bit of a happy buzz and some researchers think that that could be what’s contributing to caffeine addiction the problem is some people are way more sensitive to these stimulating effects of caffeine which can lead to them feeling

Jittery and anxious and their heart pounding one solution is to remove the caffeine all together to produce a drink with a characteristic coffee taste but none of the unwanted side effects today around 12% of all coffee consumed worldwide is decaffeinated but decaf is not just a hips a trend it has been around for much longer than you might think nearly 200 years

Ago in 1820 a german chemist first succeeded in isolating caffeine from coffee beans but was more concerned with studying the drug itself rather than actually marketing the decaffeinated bings that were left behind it wasn’t until 1905 that ludwig rosalie f developed and commercialized a method for decaffeinated coffee caffeine dissolves in water but water washes

Away other things like sugars and proteins so the key is to wash your beans in a selective solvent something that dissolves away the caffeine and leaves behind all the other molecules that give coffee its characteristic taste rosalia’s used a brine solution water saturated with salt with benzene as his solvent the problem was that benzene is a hydrocarbon found

In crude oil and one that’s been linked to some major diseases like cancer and bone marrow failure for this fairly obvious reason benzene is no longer used to decaffeinated coffee modern methods are a lot less deadly today’s techniques all aim to do the same thing starting with unprocessed green coffee beans they lynch the caffeine away to create stimulant free

Beans that can be roasted ground and prepared in the same way as normal coffee i’m gonna take you through four techniques the first two are solvent based processes number three and four aren’t so the first method is just like roselia’s but the solvent isn’t benzene anymore it’s an organic chemical like dichloromethane or efile acetate the beans are first steamed to

Open up their pores and then they’re rinsed with a solvent for around 10 hours to selectively remove the caffeine this is better but some people are concerned about the use of ethyl acetate and dichloromethane also known as ethylene chloride see they are mildly carcinogenic in high doses but strict limits are per on the amount of these chemicals that can be left

Behind on the beans after the decaffeinated treatment the beans are rinsed until the residual solvent is less than 10 parts per million and then that residual has got to survive the hi roasting heat of something like 200 plus degrees c that’s 400 degrees fahrenheit for 15 minutes or more since the caffeine removing chemicals physically come into contact with the

Coffee beans this method is known as the direct solvent technique and is sometimes also referred to as the ethyl acetate method or the natural decaffeination method because if our acetate can be found in tiny amounts in ripening fruits like blackberries and apples well then the stuff used will probably have been synthetic technique number two still uses solvents

But they never come into direct contact with your beans so it’s got the imaginative name of the indirect solvent technique the beans are soaked in hot water effectively making a really strong pot of coffee which is then drained off that liquid is then treated with the same selective solvents the caffeine bonds to the solvent that’s then heated or evaporated the

Caffeine the solvent is removed then you pour that tasty liquid packed with coffee oils and flavors but now caffeine free back into the beans so they can absorb all those flavors remove the liquid and boom decaffeinated beans right time to step away from solvents for the other two techniques the third one is called the swiss water process which unbelievably uses

Water and was pioneered in switzerland although it now looks like their factory is in vancouver again you add water to your green beans to brew a giant-sized cuppa the caffeine dissolves into the water and you drain that off through a filter of activated charcoal which acts like a net letting through most of the oil and flavor molecules but trapping the big caffeine

Molecules so you’ve now got a tank of beans with little flavor and a tank of tasty decaffeinated coffee water known as green coffee extract or gce you chuck the flavorless beans away and you replace them with a new batch then you add the gce to them that gce has a lot of flavor compounds but no caffeine so when you boil it up with the beans this time less of the

Oil and the flavors can dissolve into the solution but the caffeine still does that’s osmosis in after a few cycles of soaked drain replace repeat you get a gce that’s so packed with flavor the beans and the gce are equilibrium no flavor leaves the beans only caffeine that caffeine free flavor rich liquid can then be reused many times to suck the offending drug

From new batches of coffee beans and it reportedly leaves the beans at 99.9 percent caffeine free although the swiss water method is a lot greener than the direct solvent technique it’s still a fairly labor-intensive multi-step process and it isn’t really the most cost effective way of producing the vast quantities of decaf that you’ll find in every supermarket for

That enterprising decaffeinated have turned to science and the suitably futuristic sounding supercritical carbon dioxide extraction and it really is super critically cool and this is technique number 4 carbon dioxide is a gas that makes up naught point naught 4 percent of our atmosphere we make it in our bodies when we respire breathing out 20 milliliters of it with

Every breath but by changing its temperature and pressure you can change how it behaves and how it interacts with other substances if you increase the pressure up to around 100 times that normally found at sea level it starts to behave just like a liquid and this state is said to be supercritical what’s more this liquid like supercritical co2 has a particular pole

Chante for caffeine and when it’s forced at high pressures through water soaked coffee beans it picks up the caffeine molecules while leaving the flavor molecules behind then the co2 simply needs to be pumped out and depressurized it turns into a gas which can be used again and the caffeine is left behind making use of this ubiquitous gas is about as green as it

Gets but unfortunately the massive cost involved in pumping and pressurizing co2 means it’s not ideal for your hipster small batch coffee company so if you want a true taste of high-tech decaffeination get yourself a jar of the supermarket stuff oh and i should mention that a decaf coffee isn’t necessarily totally void of caffeine the usda says it only needs to

Be 97% caffeine-free to be labeled decaf so if you’re really sensitive to caffeine that potential 3% could be enough to cause you issues it’s a best stick to nor percent caffeine options like chicory coffee white coffee which actually isn’t very coffee like it’s actually infused orange blossoms which sounds young or just hot water as my mum’s faith don’t ask who

Would have thought that so much raw science goes into making your daily decaf the next time you sit on a cleansed coffee spare a thought for the poor beans that have been through so much to bring you your drug-free morning pick-me-up if you learn something today then have an explore of the other videos here on the channel give us a like subscribe to earth lab for

More science and regionals and i’ll see you next time

Transcribed from video
Coffee Without Caffeine | Greg Foot | Earth Lab By BBC Earth Lab