How is decaf coffee made?
Decaf coffee is coffee with the caffeine removed. The decaffeination process can be applied to beans and grinds, so decaf coffee can be purchased to use as instant or for grinders, percolators, drip machines and cafetieres.
How is Caffeine Removed from Coffee?
There are various ways that decaffeinated coffee is produced.
The process begins with the raw, green beans.
Water and solvents method:
The green beans are treated with extremely hot water to make them swell. A solvent or activated carbon is then added to extract and then dissolve the caffeine. Commonly, the solvents used are Supercritical CO², ethyl acetate or methylene chloride. The washing and extraction process is repeated until all the caffeine is removed. The beans are then roasted as normal.
Steam and solvents method:
The process is the same as above, but steam replaces the water to swell the beans. After steaming, the solvents are added and then removed via an evaporator. The beans are then washed, and the process is repeated a few times before the roasting begins.
Swiss water process:
In this method, a charcoal filter is used in conjunction with highly compressed CO² and hot water. Unlike the other methods where the first batch of green beans are re-treated and will be roasted, the Swiss water process discards them. The first batch is removed, leaving behind a solution that is saturated with flavour compounds. A new batch of beans is then added for the caffeine to be absorbed by the solvent.
Sparkling water process:
In this method, the beans are treated with hot water or steam and CO². Then they are transferred to a different tank to be washed with sparkling water to remove the CO² and caffeine.
To be called decaf, roasted coffee beans must contain no more than 0.1 per cent caffeine and the caffeine content in soluble (instant) coffee must be no more 0.3 per cent.