CO2 Is Good for Something: Decaffeination!

Caffeine MoleculeThis month, we’re very excited to announce the replacement of our previous water-process decaffeinated teas with our new CO2 decaffeinated offerings.  But many of our enviro-conscious customers may be wondering why we’re so excited about using CO2 for anything related to our generally Earth-friendly little tea company.  Don’t we go to great lengths to eliminate or offset the emission of CO2 from our business?  Well here’s a bit of background to explain why CO2 isn’t so bad for decaffeinating tea.

How CO2 Decaffeination Works

CO2 is a non-toxic, nonflammable, colorless and odorless gas which is a naturally-occurring part of the air we breathe.  Although elevated levels of CO2 in our atmosphere contribute to global warming, it’s generally a pretty inert substance.  Under pressure and temperature, however, CO2 is able to flow freely through natural materials (like tea) and has strong solvent capabilities. This is called its “supercritical” state (which is why CO2 decaffeination is also referred to as “supercritial CO2 decaffeination” or “supercritical fluid extraction,” but this is a blog for tea drinkers, not chemists…).

To begin the CO2 decaffeination process, the tea leaves are moistened and placed under pressure.  Then streams of pressurized and heated CO2 are passed through the tea leaves, where it dissolves the caffeine while leaving the tea leaves otherwise intact.  After passing through the tea leaves, the caffeine-laden CO2 is filtered to remove the caffeine, and then recycled for further use in decaffeination. Finally, the newly-decaffeinated tea leaves are dried.

How CO2 Decaffeination Stacks Up to Other Methods

In addition to CO2 decaffeination, two other methods are used for decaffeinating tea: ethyl acetate and water process.  In both cases, the tea leaves are bathed in either of these substances, which dissolve and remove the caffeine.  Unfortunately, both of these approaches have drawbacks which make them inferior to CO2 decaffeination.  In the case of ethyl acetate, traces of this organic compound (not the good kind of “organic,” mind you) can be left behind on the tea, which is generally felt to be unhealthy for human consumption.  Water process, on the other hand, is absolutely healthy, but essentially amounts to a pre-infusion of the tea leaves, in which a portion of the desireable compounds in the tea (that contribute flavor, aroma, etc.) are removed with the caffeine.

 Is CO2 Decaffeination Safe for the Environment?

In a nutshell, yes.  Because the CO2 used for decaffeination is filtered and recycled at a rate of around 99%, very little CO2 is emitted into the atmosphere.


November 30 2008 09:55 pm | Products and Tea Facts

6 Responses to “CO2 Is Good for Something: Decaffeination!”

  1. Alty on 13 Dec 2008 at 3:26 pm #

    Thanks for the information. this is the first i have heard of this process. I am excited to share this with my patients. I wonder if they are using this with coffee as well?

  2. Julia Stevens on 08 Oct 2010 at 5:32 am #

    Please could you tell me which brands of tea and coffee use the CO2 method of decaffeination.
    Thank You
    Jula Stevens

  3. Aubrey on 08 Oct 2010 at 9:52 am #

    HI Julia -

    Unfortunately, I don’t know which brands use which method. However, you should be able to ask each company to get the answer. Sometimes, they even publish it on their packaging. I can tell you that we, at Arbor Teas, only use the CO2 method!


  4. Peter Zezula on 17 Feb 2011 at 4:52 pm #

    Glad CO2 works for decaffienating tea and coffee with enough left over for all the plants on this earth, without CO2 plants would die.

  5. Joseph Delco on 06 Jan 2013 at 3:54 pm #

    Does the CO2 process still leave all the antioxidents in green tea ?

  6. Aubrey on 09 Jan 2013 at 11:09 am #

    Hi Joseph -

    No, the CO2 decaffeination process reduces the amount of antioxidants in the tea leaves. However, according to tea “technologist” Nigel Melican, tea decaffeinated using the CO2 method retains 92 percent of its polyphenols (antioxidants) compared to tea decaffeinated using the ethyl acetate process, which only retains 18 percent. (Source: “Caffeine and Tea: Myth and Reality” by Nigel Melican. February 6, 2008

    Arbor Teas

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