Stripping the stimulant — A look at decaffeination
Author: Denise Date Posted:1 March 2016
For some, caffeine has long been considered a necessary evil when the desire to enjoy a good cup of tea arises. While the thought of caffeine makes a few tea drinkers feel uneasy, the concept of decaffeinated tea (or coffee) tends to rate even lower.
For some, caffeine has long been considered a necessary evil when the desire to enjoy a good cup of tea arises. While the thought of caffeine makes a few tea drinkers feel uneasy, the concept of decaffeinated tea (or coffee) tends to rate even lower. This is partly due to the long held belief that decaf products lack flavour due to the same process that removes the caffeine.
What’s more, anything labelled as “decaf” doesn’t mean a complete absence of caffeine. As a rule, decaf brews should only contain about 1-2.5% of the original caffeine content. If caffeine is an absolute no-no in one’s diet, then non-caffeinated herbs, fruit infusions, and rooibos tisanes are the best options for a cuppa.
Tea and coffee drinkers who are familiar with the decaffeination process may also be wary of the methods used, particularly in regards to chemical solvents. Tea and coffee products that may contain any chemical residues are usually only found amongst supermarket brands and these levels are generally minute. Every year, 10,000 tons of decaffeinated tea is produced worldwide employing one of the following three methods:
- Decaffeination by ethyl acetate
- Decaffeination by methylene chloride
- Decaffeination by carbon dioxide (CO₂)
Ethyl acetate is considered a fairly natural way of removing caffeine as it is simply a chemical compound that already exists in certain ripe fruits and plants. Though due to the amounts that are required for the decaffeinating process, synthetic ethyl acetate is usually applied. However, because ethyl acetate is originally known for being organically derived, some brands that use this process may label their decaf products as being “naturally” or “organically” decaffeinated. Acting as a solvent, ethyl acetate molecules bind to the caffeine molecules to lift them away. Conversely, it also has the tendency to remove more flavour and polyphenols (antioxidants) from the tea than other processes, but is primarily used because of its low cost.
Methylene chloride is a decaffeination method that has been around longer than ethyl acetate but is applied in much the same way. The advantage of using methylene chloride is its specificity for binding to caffeine molecules — the caffeine is dissolved without heavily compromising the flavour components. There has been a lot of literature investigating how much methylene chloride is actually safe for human consumption. Some sources have claimed that it can be carcinogenic in animals whilst other research has claimed that it is not linked to any known diseases (in humans). Either way, very few traces of the solvent are left in the tea after it is heated due to its volatility, allowing it to vaporise at just 40°C. These traces are about two parts per million which is under the European Union’s set limit of 5 parts per million.
Direct and indirect decaffeination
Ethyl acetate and methylene chloride decaffeination methods can be achieved either directly or indirectly. Directly, the tea leaves are soaked in the solvent and then steamed to remove most of the solvent. On the other hand, the indirect method requires the tea leaves to be washed in water and then the water itself is treated with the solvent. This solution is then reabsorbed by the tea leaves in order to return the flavour and oils that were also washed out with the caffeine.
Lastly, decaffeination by carbon dioxide is the most recent method to be utilised. This odourless, naturally occurring chemical compound is considered the most effective and non-toxic option for decaffeination. Although the CO₂ decaffeination method is the most expensive, it is also known for being the best at preserving the flavour and health components of the tea, which is why The Tea Centre supplies decaffeinated teas produced only by this method. In this process, the tea is moistened and placed in a pressurised chamber where CO₂ is pumped in to. At high pressures and high temperatures, CO₂ reaches its ‘supercritical’ point, which is a state that allows it to behave partly like gas and partly like a liquid. This supercritical CO₂ then acts as a solvent as its small molecules bind to the small caffeine molecules. The CO₂ molecules are too small to attract the larger flavour molecules, thus keeping them intact. The tea leaves are then dried back to their original glory sans the bulk of their original caffeine content.
For the most part, when weighing up risks associated with consuming either caffeine or decaf, the risks are fairly negligible. Keep in mind caffeine content can vary when it comes to different tea varieties, growing methods, and selected leaves. Even time and temperature can affect the amount of caffeine that is transferred into a cup of tea. But in general, caffeine can be beneficial when working synergistically with the amino acids and antioxidants that are found in tea. Of course, because caffeine tolerance varies between individuals, decaf is always a good option when wanting to enjoy a traditional cup of tea.