Science in little things #1 – Making a cup of tea

The other day I was making tea. I have developed a liking for tea since I had to reduce the daily amount of coffee I introduce in my poor body and, while I was preparing my afternoon cup, I suddenly thought about how much science I can see in a simple cup of tea. Then I thought “Irene, don’t be selfish and share these thoughts”, so here I am beginning a new series of posts: Science in little things.

Do you know what a solid-liquid extraction (also called leaching) is? It seems some strange laboratory technique, right? Wrong. Or better, not only. It’s nothing more than a cup of tea.

Solid-liquid extraction is a process that can be used to extract substances from a solid matrix by using a liquid solvent. Whenever you prepare an infusion, you use this process: hot water (the solvent) seeps through the solid’s micro-porosities so that the solutes (soluble and aromatic substances), that are dispersed into the solid (tea leafs for instance), are dissolved in the liquid. The difference of concentration, which is higher into the solid phase and lower into the liquid phase, results in the diffusion of the dissolved substances into the solvent. That’s why when you put a teabag into hot water you can see a sort of coloured cloud spreading through the water. Easy like that.

Next time you are making tea or coffee and someone asks you “what are you doing?” you can answer “I’m performing a solid-liquid extraction”. Then write to let me know the reactions, please.

Just another thing: do you know that theine and caffeine are the same molecule and a cup of tea contains more or less the same amount of caffeine contained in an espresso?

Stay tuned for other “science in little things” posts!

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