Coffee without the hit

A week or to ago I explained the effects that caffeine has on your brain and body. However, there are certain people who can not handle the effects of caffeine and instead drink coffee for the pure delicious taste rather than its fantastic ability to get you through your day.

But how exactly do you get the caffeine out of the coffee bean?

Prepare to science!!

The decaffeination process starts off the same way no matter which method you use, with the bean in its green, non-roasted state.

There are three main methods of decaffeination.

The swiss water method

Basically this method submerges the beans in very hot water – think of a spa but for coffee – which washes off the caffeine. The beans are then put through an activated charcoal filter. This filter stops the caffeine particles from moving through but the smaller particles like the oils and flavours are free to flow. These old beans are then thrown away and this flavour rich water (green coffee extract) is used to wash away the caffeine on new beans while maintaining the flavour. This is because there is already the flavour particles in the water so the ones inside the beans have no where to go – it’s too crowded out there for them so they just to stay at home.  All together this takes about 8-10 hours.

The direct solvent method

This method requires the beans to be steamed for 30 minutes which helps to open their pores (again, sounds like a lovely day at the spa). Then to remove the caffeine the beans are then rinsed with dichloromethane or ethyl acetate for around 10 hours. The solvent is then removed and the beans are steamed once again to get rid of any of the leftover solvent.


A green bean enjoying the steaming process

Some people are concerned about the use of solvent in their coffee beans – however there is only one part per million of the actual solvent used and it is also very unlikely to survive the roasting process.

The supercritical carbon dioxide method 

In this process the C02 (carbon dioxide) works to remove the caffeine. The green beans are soaked and then subjected to high pressure C02. The gas works as a solvent (like above) and removes the larger caffeine particles while leaving the smaller molecules behind. The caffeine is later removed from the C02 through a carbon filter. The gas can then be reused. This is a cheaper way of doing things, and less risky than the solvent method.

2203af76-03f1-491c-98af-6aec9d2d4750 (2)

SUPERcritical carbon dioxide

So there are the three main ways that the coffee beans can be decaffeinated. However, if you can handle it I would recommend caffeinated coffee, as there is less damage done to the flavours. Also, the decaffeination process changes the beans to a brown colour, which makes it more difficult for the roasters to know when they are done.

Hope you enjoyed learning about the decaffeination process – see on Friday for the next post!!


Grinding on the dance floor.

Last week we talked all about the science of milk, this week we are moving onto the other important ingredient in coffee – the espresso shot.

The shot is one of the vital parts of the drink. Messing this up will either leave you with a sour or bitter taste in your mouth (good milk can cover this up but only so much).

The shot process begins by grinding the beans into one of the portafilters.


The portafilter is what sits in the machine and what the shot pours out of.

The actual grind (how big or small the individual coffee grinds are) of the beans can be adjusted into different levels of coarseness through the grinder.

When the espresso shot pours it will take a certain amount of time. The ideal for this is 25-30 seconds. As the water comes down on the grinds (at about 130 pounds of force) it extracts the flavours from the grinds. However, if it is not timed right this will ruin your coffee shot.

If the shot pours too quickly then as the water runs through it does not absorb the oils or flavours in the coffee and you are left with a weak, thin espresso which tastes sour.

However, if the shot pours for too long then it is because the water sticks around for longer than it should, as it can’t get passed to the desired escape route of the coffee cup. This causes it to absorb not only the flavour but also other undesirable chemicals leaving it tasting strong and bitter.


A shot is poured

The best way to fix the extraction time is to change the grind. Water will have to force its way through a fine grind, making it take longer whereas water can rush through a coarser grind much faster. If you imagine a container of rocks and a container of sand – it takes the water a lot longer to get through the sand than the rocks as there is less space for it to get through.


It is easier for liquid to pass through larger, more coarse objects.

You can also adjust your tamping pressure as well. Tamping provides a nice flat compact bed of coffee for the water to hit and compresses the coffee grinds. A harder tamp will compact more, meaning a longer extraction time.


Tamping allows the water to hit a compact, flat surface.

Coffee extraction in its 3 stages

  1. Dark thin trickle with a strong aroma, flavour and colour that is released into the shot.
  2. The caffeine and other bitter compounds begin to be extracted from the grinds.
  3. Stream lightens in colour and then the more unpleasant, more bitter acids begin to be extracted.

So next time you get your coffee and it tastes bitter or sour – or just not quite right, you now know why! (I don’t know if that will make you feel better about it or not though).


Adenosine and Caffeine, the impostor!!

Monday morning rolls around and it’s tough. Even after two full days to laze around and rejuvenate yourself – that early morning alarm kills. So you do what you always do, press dismiss, grit your teeth and reach for that cup of joe.

Caffeine is a vital part of coffee and is one the main reasons that people drink it so often and in such large quantities. Have you ever wondered how it stops you from being sleepy and why you need to keep drinking it to feel its effect?

The human brain consists of a variety of chemical reactions to keep it and you going throughout the day. It does this through a bunch of different chemicals. These molecules need to bind to their assigned receptors in order to work. Adenosine – a neuromodulator that helps you relax and wind down- builds up in quantity throughout the day which is why you (hopefully) wake up feeling refreshed and are ready to be tucked into bed by late.


Adenosine binds with its receptors in the brain.

Caffeine however is a sneaky one. It is the same shape and size as adenosine and so when it enters the mix they compete. Caffeine binds to the same receptors which therefore blocks adenosine’s effects, stimulates your nerve cells and stops you from feeling tired.


Caffeine enters the picture and steals adenosine’s spot.

There is a catch though with long term caffeine use, your brain cottons on and creates more adenosine receptors to combat it – meaning you have to have more caffeine in order to keep the sleepiness away.


More receptors means more caffeine to keep you feeling alert.

Caffeine also has a half life of six hours inside your body which means after six hours it has half the effect that it did initially which is another reason why you need to keep having more throughout the day to keep you awake.

So now you know what is going on in your brain and why you feel so alert as you sip on your morning brew.