How Coffee is Decaffeinated

sleepyDecaf coffee gets a bad reputiation, and for good reason.  Thanks to Sanka, most of the decaf coffee that has been sold over the years comes from dismally poor stock.  The original bean was poor quality and the decaf processing too damaging.

However, roasting your own coffee affords you the luxury of getting decaffeinated coffee that comes from specialty grade stock.  When you start with a great bean that is carefully decaffeinated, you get a cup of coffee that can stand on its own.

 Now, I won't lie.  A good decaf will never beat a good regular.  No matter how good the processing, the bean has been tampered with and there is no way around that.  Caffeine naturally occurs in coffee, whereas that decaf soda you are drinking isn't.  Decaf soda isn't really decaffeinated, it's uncaffeinated.

It's helpful to know how coffee is decaffeinated for three reasons:

  1. It's cool in a geeky kind of way
  2. It affects flavor, which is why we're here right?
  3. Some people have health concerns, which in my opinion are unnecessary.

The General Idea

First, the coffee is picked and processed like any other coffee that you've roasted.  But, once it is ready for market it is sent to a decaffeination facility to have the caffeine removed.  No coffee is 100% free of caffeine.  Typically you will have somewhere between 2 and 5 percent caffeine still present.  With some methods, up to 10%.

The beans must be moist at the beginning of the process and this is done using steam.  This doesn't harm the beans, while allowing them to absorb moisture gently to prep for having the caffeine removed.

Then a solvent is introduced to the coffee to extract the caffeine.  What distinguishes different decaf methods is what solvent is used and when.  Now, don't get put off by the word "solvent".  Remember, even water is a solvent.  in fact, water is the solvent that is used to extract the oils, sugars, and other flavors from the ground coffee to make your cup of joe in the morning.  Without a solvent, we couldn't drink coffee.

Once the caffeine is dissolved, the solvent is filtered away.  This process is repeated several times until the desired level of decaffeination is achieved.  The beans are then cleaned using steam and dried for consumption.

Extraction Methods: Chemical Vs. Natural

There are several methods for applying a solvent to extract the caffeine.

Swiss Water Process (WP):

The beans are soaked in warm water for a long period of time.  This extracts the caffeine into the water.  The water is then filtered away.  The problem here is that as a solvent, water is not specific to caffeine.  Water can dissolve just about anything given enough time.  It doesn't leave the good stuff behind in the bean.  Oils, sugars, and other essential flavor compounds are pulled out with the caffeine making for a dull cup when compared to it's original counterpart.

The applied solution to this problem has been to use water that also contains large amounts of green coffee extract taken from other green coffees.  This green coffee extract water is used to soak the beans after the caffeine is removed in an attempt to return some of the flavor to the bean.  it's a noted improvement, but still doesn't produce the best decaf flavor.

Most people looking for the best decaf flavor, don't go with a WP decaf unless they are scared off by the chemicals involved in other methods.

Mountain Water Process (Royal Select Water Process):

This is a relatively new water processing method performed by a facility in Mexico using glacier water from the high mountains of mexico.  There is some mystery to this method since the process is the same as SWP, but is yielding truly amazing results.  It's unclear what is making the difference, but I can tell you these are the best decafs I've tasted.

This is my preferred decaf method, and is popular not only because of the flavor but there are no scary chemical names to explain.

Methyl Chloride (MC):

MC is a solvent that is much more specific to caffeine, thus making it ideal for decaffeination because it removes much less of the oils and sugars needed to make coffee taste good.  MC is applied in two possible ways:

  • DIRECT - The beans are rinsed in MC to extract the coffee.  They are then washed in hot water, then steamed for a final cleaning.
  • INDIRECT - The beans are soaked in near boiling water to extract the caffeine and that water is separated from the beans.  MC is then applied to the water to extract the caffeine.  The coffee-water, now without caffeine, is now reintroduced to the beans to soak back in the coffee essence from the water.

Until Royal Select came along, this was the best tasting decaf out there and some argue that it still is.  Some people get concerned about the chemical name and feel that it isn't natural.  I believe those concerns are not neccessary.  Here's why:

  • MC is a solvent and so it cannot chemically bond with the coffee bean.
  • The USDA regulates the use of MC and they allow up to 10 PPM (parts per million) on a coffee bean.  The worst MC processors will render 3 PPM.  The decaf that we buy is always less than 1PPM, which is considered trace amounts that is barely worth measuring.  If you have read MC health warnings, those are referencing direct exposure to MC in concentrations over 25PPM.
  • MC is 100% destroyed at temperatures over 170 degrees.  Roasting coffee brings the bean well over 400 degrees (not to mention that if you're doing it right, you are brewing at 200 degrees).  So, those harmless trace amounts of Methyl Chloride are gone by the time you pour a cup.

Ethyl Acetate (EA or Natural):

Ethyl Acetate is another chemical that can be used as a solvent to remove caffeine.  It is employed using the same methods as Methyl Chloride.  The difference is that EA occurs naturally in many fruits which is why EA processors like to call it "Natural" to distinguish themselves from MC coffees.