The Science of Sustainability

How Do You Decaffeinate Tea?

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The Water Processing Method.

There are some traditions I have around writing. First off, in my apartment I have my write or do nothing chair. The only two things I am allowed to do in it are write or do nothing. It is where I am sitting right now as I am type this. The second tradition is classical musical in the background; this is especially helpful for long bouts of writing requiring more focus. The third is a pot of tea. The third tradition is problematic late at night, as then I don’t sleep due to the caffeine. Which made me ponder an alternative and how it is derived – how is tea decaffeinated?

Real tea comes from the leaves from the Camellia sinesis or Camellia assamica plant . These leaves naturally contain caffeine in varying amounts. Black teas are the most strongly caffeinated while white teas contain the least amount of caffeine. At night, one could drink herbal tea but these are not actually genuine teas. They are just herbal tinctures derived from other plants.

One could enjoy an actual cup of decaffeinated tea by pouring out the first cup and re-steeping. This works best with loose-leaf tea; about 80% of the caffeine in tea is released in the first thirty seconds of steeping. Pouring out the first batch steeped and then adding more hot water will get rid of the majority of caffeine while maintaining the flavor of the tea.

This is the water method of decaffeination. There are three other methods used for decaffeination:

Methylene chloride processing – in this process Methylene chloride is used as a solvent. Molecules of caffeine bond to the molecules of Methylene chloride. This processing can be done directly in a bath of Methylene chloride or indirectly by extracting the caffeine in a water bath.

Ethyl acetate processing – Ethyl acetate is a naturally occurring chemical in most fruits. Caffeine molecules bond to Ethyl acetate and caffeine can be removed either directly or indirectly using Ethyl acetate as the solvent. Products coined as “Naturally decaffeinated” are usually decaffeinated using this method.

Carbon dioxide processing – In this process, water softened materials are “pressure cooked” with the gas. At high pressures, CO2 sublimates and acts as both a gas and a liquid. As a solvent, the non-polar molecules will attract the smaller caffeine molecules. Since the flavor molecules are larger they remain intact. This process retains the flavor of the tea better than the other two solvent methods.

In all these methods some caffeine will remain but it drastically reduced. Federal regulations in the US mandate that labeled decaffeinated products must not contain more the 2.5% caffeine. So what happens to all the caffeine that is taken out in processing? It is put into other products. Soft drinks are primarily caffeinated from the caffeine taken out from decaffeination. So that soft drink might include the caffeine from tea leaves or coffee beans. So by choosing decaffeinated tea tonight, that caffeine was repurposed in another caffeine beverage!

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Cat

About the Author ()

Cathleen (Cat) is the former Special Projects Manager at California Academy of Sciences and worked in the public programs division. Before working at the Academy, Cat got her start as an intern at Lindsay Wildlife Museum for four years and worked with animals ranging from snakes and hawks to foxes and bobcats. She has a deep curiosity about the natural world and native California wildlife.