How Is Tea Decaffeinated?
You probably already know that all tea leaves naturally contain caffeine. However, depending on their oxidation level, there is more or less caffeine in them. Black teas, with the most oxidized tea leaves, have the highest level of caffeine. That level goes down in the less oxidized oolong, green and white teas.
However, our civilization has also found ways to decaffeinate tea leaves so that people who are sensitive to caffeine or people who love to have a cuppa in the late afternoon can enjoy. All types of tea can be decaffeinated, but most commonly you may find decaf black and green tea.
Decaffeinated Tea vs Caffeine-Free Teas
Often interchanged, these two terms are not synonyms. You must know that decaf teas are different than caffeine-free teas. Decaffeinated teas actually still have a little bit of caffeine left in them although the amount is very, very minimal (usually 2 mg of caffeine per cup). While the caffeine-free teas naturally don't contain any caffeine. These are normally herbal tisanes like mint tea, rooibos, chamomile, etc.
How Is Tea Decaffeinated? Discover the Different Tea Decaffeination Methods.
There are four methods of tea decaffeination: methylene chloride, ethyl acetate, carbon dioxide, and water processing. Here, we've shortly explained how each of them works and what the effect of the process is on the tea and tea flavour.
- Methylene Chloride: Using this method, caffeine is removed by soaking tea leaves in methylene chloride directly or indirectly, by soaking the water (used to remove the caffeine) in methylene chloride and then returning the water to the tea for re-absorption of flavors and oils. It is a decaffeination process by which the molecules of caffeine bond to molecules of methylene chloride. It is believed that methylene chloride is not the best possible and healthiest method of decaffeinating, although this process is noted for maintaining more of the original flavor of the tea than other methods. It is forbidden to import teas treated this way in some countries.
- Ethyl Acetate: Tea processed using ethyl acetate is often referred to as “naturally decaffeinated” because ethyl acetate is a chemical found naturally in tea. The solution also used as a solvent where caffeine is extracted in the same way as with methylene chloride processing. Harney & Sons are using this method for decaffeinating tea bags as tea tastings and customer feedback has shown that this is a preferred method for the tea bags. Loose tea and tea sachets on the other hand are being decaffeinated using the Carbon Dioxide method described below.
- Carbon Dioxide (CO2) Tea Decaffeination: This is the method that Harney & Sons use to decaffeinate their loose teas and tea sachets. It is also known as a natural method of decaffeination that allows for retaining the tea flavours and health benefits. How tea leaves are normally treated with this method is basically “pressure cooking” them with this naturally occurring gas. At high pressure and high temperature, carbon dioxide reaches the so called super-critical state where CO2 becomes a solvent and with its small, non-polar molecules it attracts the small caffeine molecules and removes them from the tea leaves. Since flavor molecules are larger, they remain intact, which is why this process best retains the flavor of the tea.
- Water Processing Decaffeination: Caffeine extraction with water is not a primary way for tea decaffeination. In fact it is more popular as a coffee decaffeination method, although a small amount of tea products are decaffeinated using this method. After the caffeine is removed from the tea by soaking the tea in hot water for a period of time, the solution is passed through a carbon filter for caffeine removal. The water is then returned to the tea for re-absorption of flavors and oils. People who have tried water processing decaffeinated tea describe the flavours as “watered down”.