The naturally-occurring caffeine in tea leaves can be removed through four different decaffeination processes. Two use chemical solvents (ethyl acetate and methylene chloride) while one uses carbon dioxide and another uses water.
The carbon dioxide process is the most natural and is the best at preserving the flavour of the tea while eliminating the caffeine. It also removes less of the antioxidants, vitamins and minerals than the other methods.
Water Process
A simple run under hot water will remove some caffeine from tea, but this process also degrades the important health benefits such as polyphenols. Fortunately, there are some ways to enjoy the rich taste and natural energy of green tea without any of its caffeine.
One of the simplest methods involves steeping the tea leaves in a small amount of boiling water for just 30 seconds to a minute. It is believed that this method can reduce the caffeine level by about 80 percent. This is a great option for those who are not interested in the chemical-based processes used to decaffeinate tea.
This method uses water to brew the tea, and then the water is filtered to catch the caffeine molecules. The leaves are then rehydrated with the water that was used to filter out the caffeine, which allows them to absorb all the essential oils and flavors that make green tea so delicious.
The Water Process is the most popular way to decaffeinate green tea because it is a safe, environment-friendly and inexpensive alternative to organic solvents. However, this method only removes about 96-98% of the caffeine molecules from the tea leaves and may leave behind an unpleasant chemical flavor. Therefore, many people still choose the more efficient, less harmful, and healthier carbon dioxide (CO2) decaffeination process.
Ethyl Acetate Process
The ethyl acetate decaffeination process is a popular method. It involves soaking tea leaves in a solvent called ethyl acetate to capture polar caffeine molecules and remove them from the leaf. This process can also be used to decaffeinate coffee beans.
This is a less-reliable method because it can leave the tea with a chemical flavor, especially if it’s not done well. It’s also difficult to use for larger scale production.
Another downside of this method is that it strips away some of the tea’s antioxidants, especially catechins. This can lead to a weaker tasting tea and less health benefits.
One benefit of this method is that it doesn’t involve any chemicals, unlike the methylene chloride process. It’s also more sustainable than other methods because it doesn’t need to be flushed down the drain.
However, it can still be a health risk because ethyl acetate is toxic and can leave a chemical taste in the tea. This is why it’s not considered a healthy option by many.
Another option is carbon dioxide decaffeination, which can be done at a much larger scale. This involves placing the tea leaves in a closed container and putting it under enormous pressure. This pressure turns the CO2 into a liquid and it’s then forced through the tea leaves to bind with the caffeine and remove it from the leaves. This is the most environmentally friendly and safe method, but it can still strip some of the tea’s antioxidants.
Carbon Dioxide Process
Carbon dioxide is one of the most abundant naturally-occurring gases in the atmosphere, and plays an important role in vital plant and animal processes like photosynthesis and respiration. Carbon dioxide is found in the air we breathe, dissolved in water and in foods such as fruits and vegetables. It is also used to produce synthetic fuels, as a refrigerant and in the production of carbonated beverages.
The Carbon Dioxide Process, discovered by Kurt Zosel in the early 1970’s is a safe, non-toxic and effective method of decaffeinating green tea. The basic method is to soak the tea leaves with liquid CO2 at a high temperature and pressure, which causes the caffeine molecules to bond to the CO2. The CO2 can then be easily removed from the tea, leaving behind only the naturally-occurring caffeine-free antioxidants called catechins.
Carbon dioxide is readily available in high-pressure cylinders, as a refrigerated liquid or as dry ice. It has many uses including refrigerating and cooling equipment, in fire extinguishers for inflating life rafts and life jackets, blasting coal and foaming rubber and plastics. It is also used to promote the growth of plants in greenhouses and immobilize animals before slaughter. Carbon dioxide is a component of the carbon cycle, wherein carbon is transferred between the atmosphere, terrestrial biosphere (which includes soil and freshwater systems), oceans, and sediments including fossil fuels. Concentrations of carbon dioxide in the atmosphere are increasing largely due to human activities like burning fossil fuels for energy, and are currently 387 parts per million—the highest concentration in two million years.
Methylene Chloride Process
The methylene chloride process is a method for decaffeinating tea which is used in some countries. The methylene chloride molecules bond with the caffeine molecules, so they can be removed from the tea leaves, leaving behind only small amounts of caffeine. This method is also less harmful to the environment than other methods of decaffeination. Teas decaffeinated using this method are sometimes contaminated with methylene chloride, but it is usually at a level that is acceptable for human consumption. Methylene chloride is a commonly used chemical and is found in paint strippers, nail polish removers, wood preservatives, metal cleaning and finishing, odor removal products and as an auxiliary blowing agent for slabstock flexible polyurethane foam production.
There is one downside to the methylene chloride process; it may leave your tea with a slight flavor profile that tastes like chemicals. The methylene chloride is also a carcinogen and has been linked to many diseases including cancer. Because of this, some countries have banned teas processed with methylene chloride. In the United States, only trace levels of methylene chloride are allowed in food and beverages, five parts per million.
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