Caffeine is naturally present in all tea leaves, but the amount of caffeine in different types of tea varies, depending on their level of oxidation. The largest caffeine content is found in black teas, which have the most oxidised tea leaves. In the less oxidised green and white teas, the level of caffeine decreases.
At Welsh Brew Tea we know that Decaf Tea and Decaf Coffee are becoming more popular, as some people prefer a cuppa in the late afternoon without the wake-up effects! Or if they are simply sensitive to caffeine. The clever boffins have developed ways to remove the caffeine from tea, without losing that lovely flavour. Bit how do they do it?
The Methods for Decaffeinating Tea…
Methylene chloride, ethyl acetate, carbon dioxide and water processing are the four techniques used to decaffeinate tea. Here, we’ve provided a brief explanation of how each method works and how the procedure affects the tea’s flavour.
Methylene Chloride:
In this procedure, the caffeine is removed by either directly or indirectly soaking the tea leaves in methylene chloride, or by soaking the water used to extract the caffeine in methylene chloride and then re-absorbing the flavours and oils in the tea. Caffeine molecules form bonds with methylene chloride molecules during this decaffeination process. Although methylene chloride is known to preserve more of the tea’s original flavour than other procedures, it is not thought to be the most effective or healthiest way to decaffeinate. In several countries, importing teas that are processed in this way is prohibited.
Ethyl Acetate:
Since ethyl acetate is a naturally occurring molecule in tea, tea that has been processed with it is frequently referred to as “naturally decaffeinated”. In the same method as with methylene chloride processing, the solution is also utilised as a solvent for the extraction of caffeine. Tea tastings and consumer feedback tell us that this is the preferable procedure for tea decaffeination. In contrast, the carbon dioxide procedure outlined below is used to decaffeinate loose tea and tea sachets.
Carbon Dioxide (CO2) Tea Decaffeination:
It is often referred to as a natural decaffeination process that preserves the health advantages and flavours of tea. Typically, this technique involves “pressure frying” tea leaves using this naturally occurring gas. When carbon dioxide reaches the so-called super-critical state at high temperatures and pressures, it turns into a solvent and draws in small, non-polar molecules of caffeine, which it then extracts from the tea leaves. This method preserves the tea’s flavour the best since the flavour molecules are bigger and stay intact.
Water Processing Decaffeination:
Tea decaffeination is not primarily accomplished via water-based caffeine extraction. Although a tiny number of tea products are decaffeinated using this method, it is really more commonly used as a coffee decaffeination method. Following a length of time spent soaking the tea in hot water to extract the caffeine, the mixture is then run through a carbon filter. After that, the water is added back to the tea so that the tastes and oils can be reabsorbed. Those who have sampled decaffeinated tea that has undergone water processing say the flavours are a bit weaker.
Comparing Caffeine-Free and Decaffeinated Teas…
It’s worth noting that caffeine is naturally absent from some caffeine-free teas. These are typically herbal teas, such as chamomile, mint tea, and rooibos. Although the level of caffeine can be extremely small — typically only 2 mg of caffeine per cup.
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