All tea plants contain theine. To make tea theine-free, the theine must be filtered out.
There are four methods of decaffeinating tea: methylene chloride, ethyl acetate, carbon dioxide, and water processing. Below is a brief description of what these methods entail.
Methylene chloride : The simple process uses a solvent called methylene chloride, which is widely used in the food industry, for example in the extraction of hops in the beer industry, or an alternative way of decaffeinating coffee beans. With this method, theine can also be removed from the tea leaves by soaking them directly or indirectly in methylene chloride. It is a process of making theine free in which the molecules of theine bind to the methylene chloride molecules.
While this process is known for retaining more of the original tea flavor than other methods, methylene chloride is not believed to be the healthiest method of removing theine. In some countries it is even forbidden to import tea treated in this way. That is why the Groene Hart does not use this method.
Ethyl Acetate : Tea processed with ethyl acetate is often referred to as "naturally caffeine-free" because ethyl acetate is a chemical naturally found in tea. The solution is also used as a solvent with theine extracted in the same way as in methylene chloride processing. Unfortunately, it is a very time consuming and costly process.
Water processing : Theine extraction with water is not the most common way of making tea theine-free. After the theine has been removed from the tea by soaking the tea in hot water for a while, the solution is passed through a carbon filter to remove the rest of the theine. The water is then returned to the tea for reabsorption of flavors and oils. People who have tried decaffeinated tea with water describe the flavors as "watered down".
Carbon dioxide (CO2) : this is the method used by Groene Hart to make loose teas deine free. It is also known as a natural decaffeination method that preserves the tea flavors and health benefits. How tea leaves are normally treated with this method is basically "pressure cooking" with this naturally occurring gas. At high pressure and high temperature, carbon dioxide reaches the so-called supercritical state in which CO2 becomes a solvent and with its small, non-polar molecules it attracts and removes the small theine molecules from the tea leaves. Because flavor molecules are larger, they remain intact, which is why this process best preserves the flavor of the tea.