The Decaffeination of Coffee

Every day, millions of people around the world drink coffee. While most enjoy it in its natural state, as a mixture used without separation, many prefer ‘decaf’, as it does not provide them with unnecessary energy, and some cannot have excess amounts of the stimulant as it causes adverse effects. Therefore, the process of decaffeination is very important in today’s society.

There are various ways in which coffee can be decaffeinated. The solubility of caffeine allows it to be removed easily using solvents.

1. The Carbon Dioxide Method

This method was developed by the Kurt Zosel. For a very long time, toxic compounds such as Chloroform and benzene had been used to decaffeinate coffee. The carbon dioxide method, however, does not use any chemicals and allows the coffee to retain the proteins and carbohydrates that give it its flavour.

The method uses two natural elements, pure water and carbon dioxide. The carbon dioxide is between a gas and a liquid (‘supercritical’) and acts as a solvent.

Firstly, the beans (in their green stage) are mixed with pure water, which causes them to expand to double their original size and opens their pores.

The caffeine molecules are then able to move freely. Carbon dioxide is added to the pure water, which absorbs all the mobile caffeine molecules.

After this process, the beans are dried naturally.

This diagram illustrates this method.

2. Swiss Water Process

In Switzerland in the early 1930s, it was discovered that water could be used to decaffeinate coffee. Forty years later, when the technology became available, the discovery was able to be put into practice. In 1989, the only SWISS WATER® decaffeination facility in the world was built near Vancouver, Canada, a region well-known for its pure, high-quality water.

In this process, a batch of coffee beans is first soaked in water, which removes some of the flavour. This first batch is discarded. The now ‘flavour-saturated’ water is put through a carbon filter, which removes the caffeine but does not touch the flavour components trapped within the water.

A new batch of coffee beans is added to the water. They absorb the flavour of the water while their caffeine is drawn out using the carbon filter. After this, the beans are dried and ready to be roasted.

3. Ethyl Acetate/Methylene Chloride

Similar processes are used for both of these chemicals. The green coffee beans are put into a rotating drum and steamed in order to soften them, then rinsed repeatedly with methylene chloride (a solvent) to remove the caffeine.

The solvent, now carrying the removed caffeine, is drained and the beans are once again steamed so the solvent can fully evaporate. A vacuum is used to dry out the coffee beans and ensure there is no chemical residue.

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