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8th May 2009
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13th May 2009

I was asked the other day how do you get the caffeine out of coffee to make it decaf but I wasn’t sure so I looked it up.

Standard coffee beans have between 0.8 percent and 2.5 percent caffeine depending on there origin and type.

There are several processes for decaffeinating coffee but the main methods are the water and direct method:

Water method

The water method is typically called the swiss water method because it was invented by the Swiss Water Decaffeinated Coffee Company. The green coffee beans are soaked in hot water to remove the caffeine and compounds responsible for much of the flavor of the coffee flavor. The first batch of coffee beans is then discarded, while the caffeine is stripped from the solution by means of activated carbon filters. This leaves a solution saturated with flavor compounds, which is then used to soak a new batch of decaffeinated green coffee beans. The principle of water procesed decaf coffee is that the solution is saturated with all components soluble in water other than caffeine. Therefore, only the caffeine in the bean is allowed to escape whereas the rest of the compounds are in equilibrium. Unfortunately, the flavor of batches is intermixed since the chemically saturated solution is used repeatedly.

The process takes approximately 10 hours resulting in green beans that are 99.9% caffeine-free.

Direct method (or Dichloromethane)

In the direct method the coffee beans are first steamed for 30 minutes and then repeatedly rinsed with either methylene chloride (Dichloromethane/DCM) or ethyl acetate for about 10 hours. The solvent is then drained away and the beans steamed for an additional 10 hours to remove any residual solvent. Sometimes coffees which are decaffeinated using ethyl acetate are referred to as naturally processed because ethyl acetate can be derived from various fruits or vegetables, but because of the impracticality of gathering natural ethyl acetate, the chemical used for decaffeination is synthetic.

Even after the process almost all brands of decaffeinated coffee still contain some caffeine. Caffeine free beans were discovered in 2004 so over the next few years you could see these processes die out at more naturally decaffeinated beans are grown.

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