Decaffeination
Caffeine is usually obtained as a bi-product of the decaffeination of coffee. It is removed from the green coffee beans prior to roasting. Initially the method was to use an organic solvent which obviously was not ideal as and any residue may be both harmful and difficult to remove, as well as adversely affecting the flavour of the coffee. The next method employed was to treat the beans with high pressure carbon dioxide.
However the most recent method for decaffeinating instant coffee is to steam the green beans to remove the caffeine. The water is then treated with activated charcoal which removes the caffeine, the water is then returned to the coffee making process in order reincorporate any flavour removed by steaming.
Decaffeinated coffee still contains approximately 3 to 4mg of caffeine. Although decaffeinated forms of coffee, tea and cola are now widely available the caffeinated forms are still preferred by the vast majority of the population.