Coffee is a popular beverage that is dark brown to black in color. It is made from ground coffee beans that are grown in over 70 countries around the world. Unroasted coffee is one of the most traded commodities in the world. Coffee has a stimulating effect on humans due to its caffeine content. There has been some concern of the effect of coffee consumption on people’s health and many people have chosen to make the switch to decaf coffee. Many women also choose to drink decaffeinated coffee whilst pregnant as studies have shown caffeine to have a detrimental effect on developing babies. So how is coffee decaffeinated?
The Decaffeination process
It is not only coffee that is commonly decaffeinated. Often substances such as cocoa and tealeaves are also decaffeinated to offer healthier alternatives. Decaffeinated beverages are not completely caffeine free and still retain approximately 1-2 % of caffeine.
There are a number of different processes that are used today to decaffeinate coffee. Nearly all of the methods require soaking or steaming of the coffee beans to separate the caffeine from the other chemicals found in the coffee that gives it its taste and texture.
The first step in the direct method is to steam the coffee beans for 30 minutes. The beans are then rinsed a number of times with dichloromethane or ethyl acetate for about 10 hours. The beans are then drained of the chemicals and steamed for another 10 hours to remove any leftover chemicals.
The beans are soaked in very hot water for several hours. The beans are removed and either dichloromethane or ethyl acetate is used to extract the caffeine from the water. Once this is done the water is recycled through the system with a new batch of beans. Eventually the level is reached where the water and beans have the same composition and are caffeine free without compromising taste and flavor.
Swiss water method
This method is by far the simplest form of decaffeination. This is a method that is done by local coffee roasters. Green, unroasted beans are soaked in hot water which releases the caffeine. Once all the caffeine and coffee solids are released into the water the beans are discarded and the water filtered through a carbon filter. The filter traps the caffeine whilst allowing the coffee solids to pass through. This solution called green coffee extract is added to a new batch of green beans. The caffeine diffuses from the new beans and the liquid is again passed through the filter to capture the caffeine. This process is repeated until the beans are caffeine free. The beans are dried and retain their flavor.
The green coffee beans are again soaked in hot water and a coffee solution which draws out the caffeine to the surface of the bean. The beans are put into another container where they are covered in coffee oils. They stay in the container at high temperature for several hours. The beans are then separated from the oils and dried. The caffeine is removed from the oil which is then used to decaffeinate another batch of beans.