Methods Used in the Decaffeination of Coffee

Dr. Ludwig Roselius invented a method for decaffeinating coffee beans in 1903. Germany issued a patent for the process 1906. For years, Roselius and his team had researched a method to remove caffeine from coffee beans without diluting the coffee's aroma or flavorful taste.

His technique involved using brine-soaked coffee beans. This technique was discovered when he obtained coffee beans that had plunged into the sea during a storm. He discovered that the brine-soaked coffee beans reacted differently to the coffee roasting process than did unsoaked coffee beans.

Roselius eventually refined the decaffeinating process, and created a method that removed 97% of the caffeine from coffee beans without greatly altering the coffee's taste. Based on his method, he established a company in Germay called Kaffee Hag, and introduced the new coffee product to the world under different names in different countries.

In the United States, the Kaffee Hag product was introduced in 1923 as "Sanka," which is an abbreviated form of the French phrase "without caffeine." By 1946, "instant" Sanka was available as well.

More than 70 years after Roselius' discovery, Maxwell House discovered an innovative process to remove the caffeine from coffee beans by using carbon dioxide. In 1980, General Foods acquired the rights to use this method of decaffeination in the United States.

Today, there are three main methods used to remove the caffeine from coffee beans: 1) Swiss water decaffeination, 2) chemical decaffeination, and 3) the superficial carbon dioxide method.

Swiss Water Decaffeination of Coffee

The Swiss water decaffeination process is a two-step process involving two batches of green coffee beans. The process begins by soaking the first batch of green coffee beans in water to dissolve the caffeine. Once the caffeine has been dissolved, the water is drawn off and passed through carbon filters, which remove the caffeine from the water.

This results in the first batch of coffee beans having no caffeine or coffee flavor left. The caffeine is left behind in the filter, but the filtered water now contains the full coffee flavor without the caffeine. The first batch of depleted coffee beans is discarded. The flavor-enhanced water is then reused to remove the caffeine from a second batch of green coffee beans.

The second time around, since the water is already saturated with coffee flavor, the caffeine is removed from the coffee beans, but the coffee flavor is left intact. By this process, the second batch of green coffee beans retains its flavor and aroma, while losing the caffeine.

The second batch of coffee beans is now decaffeinated, and is ready for drying and roasting. This method removes 99.9% of the caffeine in the coffee beans, but it is expensive, because it takes two batches of coffee beans to produce a single batch of decaffeinated coffee beans.

Chemical Methods for Decaffeinating of Coffee

Chemical methods for decaffeination comprise direct and indirect methods. In the direct methods of decaffeination, the green coffee beans are first soaked in water. Then they are flushed with methylene chloride, which draws out the caffeine. The methylene chloride must then be removed from the coffee beans in a subsequent rinsing, since it has been linked to cancer in laboratory animals.

Another effective caffeine solvent is ethyl acetate, which is used more in the indirect decaffeination processes. In the indirect decaffeination processes, the green coffee beans are steeped in hot water in order to dissolve the caffeine. Then the water is separated from the coffee beans. The flavored water is treated with ethyl acetate to remove the caffeine. Finally, the flavor from the water is returned to the coffee beans via another soaking and drying process. Any remaining traces of ethyl acetate are removed in a final step.

Superficial Carbon Dioxide Method for Dercaffeinating Coffee

As in the other methods, the green coffee beans are soaked, so as to dissolve the caffeine. Then the saturated green coffee beans are exposed to carbon dioxide gas, which reacts with the caffeine and removes it. This decaffeination method is most efficiently used when large quantities of coffee beans are being decaffeinated. Therefore, this is the method most frequently used in commercial decaffeinating applications.

While the Swiss water decaffeination process is the most natural, meaning that it doesn't depend on introducing chemical solvents or gasses, it is generally not as cost effective as the other decaffeinating methods, because it uses the most coffee.