Ever Wonder How: They Decaffeinate Coffee?

May 04, 2014

    Decaffeinated coffee - to some coffee lovers who can't imagine coffee without its caffeine kick, the two words together are blasphemy. We're not just talking about those who see coffee as primarily a caffeine delivery vehicle. There are plenty of specialty coffee afficionados who would love to be able to enjoy another cup of coffee without experiencing the caffeine jitters or a sleepless night. Unfortunately for coffee lovers who have to avoid caffiene for one reason or another, it's almost impossible to remove caffeine from coffee without also removing many of the other compounds that give specialty coffees their distinct and distinctive flavors. Even so, there are many people who love coffee but can't tolerate caffeine. So coffee processors use one of several processes to effectively "wash" the caffeine out of coffee in order to produce a decaffeinated version of the world's favorite wake-me-up brew.  

coffee-kind-decaf-caffeineBasic Facts About Decaf Coffee

  A German coffee merchant, Ludwig Roselius, invented the first commercially successful process to decaffeinate coffee in 1903 and patented it in 1906 in Germany. Roselius brought decaf coffee to the U.S. around 1914, but its early adoption was interrupted by World War I. Roselius' decaf coffee company, Kaffee Hag, was confiscated by the U.S. government under the Alien Property Custodian department, and its patents and property sold to an American. After the war, however, Roselius started again, this time calling his decaf coffee company Sanka. And the rest, as they say, is history.   Decaffeinated coffee is not caffeine-free. Under U.S. law, however, decaf coffee must have 97% less caffeine than regular coffee. In most cases, the residual amount is about 5.4 mg of caffeine in a 12-oz. cup of coffee. That's in contrast to about 180 mg in a 12-oz. cup of regular coffee.   The trick in removing caffeine from coffee is to remove the caffeine without removing any of the near-1000 other soluble compounds that deliver the flavor, texture and other qualities that make coffee such a beloved beverage throughout the world.  

Four Ways to Decaffeinate Coffee

  There are four basic methods used to decaffeinate coffee. All of them involve the use of water, the universal solvent, Beyond that, the four processes break down into two distinct types: two of the four processes involve chemical solvents and two of them don't.   A word about solvents used in making decaf coffee: Roselius' decaf process involves the use of benzene, which has since been found to be a carcinogen and is no longer used in the decaffeination process. Over the years, chemists have tried a number of chemicals to dissolve and remove the caffeine from coffee, including trichloroethylene (TCE), dichloromethane and chloroform, all of which turned out to have serious health risks. Today, the most common solvents used are methylene chloride and ethyl acetate. Both have been deemed safe for use in the decaf process, particularly as neither leaves any appreciable traces in the finished product.  
  1. Direct application of solvent (sometimes called "natural process decaf)
    • As the name suggests, in this method of decaffienation, a solvent, usually ethyl acetate (though methylene chloride is sometimes used), is applied directly to unroasted coffee beans. The green beans are first exposed to steam for about 30 minutes to open their pores and allow the ethyl acetate to penetrate them. After the steaming, the beans are washed repeatedly with the solvent for about 10 hours until the caffeine is dissolved and washed away. Finally, the beans are steamed again to remove any remaining traces of the solvent.
  2. Indirect application of solvent (also called European prep)
    • Unlike the direct solvent method, in the indirect solvent method the solvent never actually touches the coffee beans themselves. Instead, the unroasted coffee beans are soaked in near-boiling water for several hours, extracting the caffeine and most other flavor compounds from them. The caffeine-laden water is then drained into another tank, where it is treated with a solvent, usually methylene chloride, that selectively absorbs the caffeine, leavng behind the other coffee oils and compounds. The decaffeinated water is then reintroduced to the tank of washed coffee beans to reabsorb most of the coffee oils and flavor compounds removed in the hot water bath.
  3. Swiss Water Decaf process  (SWP)
    • The Swiss Water decaf process is the one typically favored by American specialty coffee producers. Originally developed in 1933, it wasn't commercially used until the late 1980s. It uses no chemicals. The Swiss Water Company's decaffeination facility in Canada is the only one in the world that is certified organic by both two separate certification bodies, and has been certified Kosher by the KOA (Kosher Overseers Association).
    • In the Swiss Water process, the green coffee is first soaked in nearly boiling water for several hours, as in the indirect decaf method. However, the caffeine is not removed from the water by chemical treatment. Instead, the water is passed through activated carbon filters to remove the caffeine. The result is two tanks of water -- one with caffeinated water, and one with water that is saturated with coffee oils and flavor compounds. At this point, the original coffee beans, minus flavor and caffeine, are discarded and the flavor-saturated water is used to decaffeinate a new batch of beans. Because the water is already saturated with coffee compounds, it can only absorb caffeine from the new batch of coffee beans, so it leaves behind the coffee oils and compounds that give coffee its flavor.
    • Swiss Water Process is used almost exclusively to decaffeinate organic coffees. It is environmentally friendly, and is regularly audited to ensure that coffee decaffeinated via SWP is 99.5% caffeine-free.
    A Note about Water Process:You'll note that many of our roasters list either SWP or a different water process decaffeination method in their coffee descriptions. While Swiss Water is the best known of the decaffeination facilities, and the only one that can use the name Swiss Water Process, a number of other facilities have developed similar processes to remove caffeine from coffee naturally, using only water. Over just the last few years, we're seeing decaf coffees from top craft roasters that are top-notch in the flavor department.
  4. Carbon dioxide process (CO2 or Supercritical Decaf)
    • The carbon dioxide decaffeination process is the most recent development in the quest of delicious decaffeinated coffee. It was devolved by Kurt Zosel of the Max Plank Institute. It uses liquid Co2 to selectively dissolve and remove only caffeine from unroasted coffee beans. After the beans have soaked in the liquid carbon dioxide, it is drained and then reverted to its gaseous state, leaving behind the caffeine. Unlike most other methods, the other flavor compounds are never removed from the bean. The process reportedly preserves the most flavor in the coffee bean and uses no harmful chemicals, which should make it a natural fit for the specialty coffee industry. However, the prohibitive costs have largely confined it to use by larger coffee companies who buy and sell commodity coffees.

Decaf Coffee -- What About the Flavor?

  coffee-kind-bowtruss-decafThe biggest issue with decaffeinated coffee has always been flavor. While SWP is highly regarded as an environmentally friendly, natural and healthy way to decaffeinate coffee, some people complain that SWP decaf coffee tastes a little muddled and muddy. It seems to blunt bright acidic notes while emphasizing body, and may be more successful flavor-wise with mellower, less acidic beans. The solvent-based methods seem to favor the retention of those high, bright notes in coffee, but often seems to result in coffees with less body. It's difficult to make a really good assessment, though, even by experts, because it's difficult to find samples of the same coffees decaffeinated, roasted and brewed using similar methods.   So what do you do if your doctor informs you tomorrow that you have to cut out drinking caffeinated coffee? We recommend a great selection of decaf coffees from our favorite craft roasters on our decaf coffee page. Many roasters include which decaf method was used in their notes on the coffee. For example, Bow Truss Ethiopian Sidama Kenebata Natural Decafcoffee is decaffeinated in Europe using methyl chloride, a method that preserve the bright citrus acidity often found in Ethiopians and other East African coffees. Select your decaf coffee just as you'd select your regular coffee -- by choosing flavors you think you'll enjoy in your cup.  

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