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December 14, 2015

How is tea decaffeinated?

Filed under: Black Tea,Tea and Health,Tea preparation — wbwingert @ 10:10 am

 

This question comes up in just about every one of our tea tastings and even more often at the store. So I thought it was time to address it here in the blog.

Fact is that all decaffeination processes use a solvent to dissolve the caffeine and then remove the solvent from the tea. All methods leave some small amount of caffeine behind

Two different methods are commonly used decaffeinate tea:

  • Chemical (Methylene chloride or Ethyl acetate )
  •   Super Critical Carbon Dioxide (CO2 method)

Many commonly available teas are decaffeinated with chemical methods. These methods involve extracting the caffeine directly or indirectly with methylene chloride or ethyl acetate. In both cases, the tea leaves are moistened to allow the caffeine to be removed and then the non-caffeinated water is added back to the leaves. Methylene chloride is reported to be the most effective but in very high doses studies have shown it to be a carcinogen.

Ethyl acetate is another compound used to extract caffeine from tea. Ethyl acetate occurs naturally in tea leaves, coffee, bananas, and other types of produce. For the purposes of the decaffeination process the Ethyl acetate is synthetically produced. While ethyl acetate effectively removes caffeine from tea leaves, it can also extract other chemical components as well. Studies on green tea decaffeinated with ethyl acetate have shown the potential for up to 30% of epigallocathechin gallate (EGCG-considered to be the primary beneficial component in green tea) and other beneficial antioxidant compounds to be extracted along with the caffeine.

Highlights of the Chemical Methods

  •   methylene chloride is very effective at removing caffeine
  •   At very high does it is a carcinogen (no carcinogenic effect at low doses)
  •   Tea leaves are moistened to remove the caffeine
  •   According to studies, Ethyl Acetate removes up to 30% of the antioxidants in green tea

CO2 Method

Uses highly pressurized carbon dioxide (CO2) the gas that adds bubbles to mineral water to dissolve caffeine from tea leaves. At high pressures CO2 makes an effective solvent. In its pressurized state, CO2 is pumped into a sealed chamber containing tea, where it is allowed to circulate to remove the caffeine. From there, it is pumped into a washer vessel where water or activated charcoal is used to separate the caffeine from the CO2. The purified CO2 is recirculated into the pressurized chamber. This process is repeated until the appropriate amount of caffeine has been removed.

Highlights of the CO2 method

  • does not leave a chemical residue
  •   has a minimal effect on the flavor and beneficial compounds in tea. (For example, CO2 leaves
  •   intact approximately 95% of the original EGCG content of green tea)
  •  Generally costs more than the Chemical methods

Our Souvia Label decaffeinated teas use the CO2 method. We believe this to be the best method for you and for the tea. If you have to or would like to abstain from caffeine, we also offer a large selection of herbal teas, all of which are naturally caffeine-free.

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