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October 21, 2009, 1:21 pm

How do bubbles tickle the tongue?

You know that delicious, bubbly, tickly feeling on your tongue when you taste fizzy drinks... but how does the tongue "taste" the bubbles of carbon dioxide?

What was discovered?

Tiny bubbles of carbon dioxide in fizzy drinks stimulate the same receptors on our tongue as sour foods!

These receptors are found in the membranes of the taste receptors on the tongue, and the active part which does the tasting is called carbonic anhydrase 4. This is an enzyme, and it can send signals to nerve cells (neorons) so that we detect the taste.

How was it discovered?

Tiny electrodes in nerves from taste receptors could detect stimulation when carbonated drinks were given to mice! But which kind of taste receptors were important?

Using genetic mutants that do not have the sour taste-receptors, and also by using chemicals called inhibitors which can stop enzymes such as carbonic anhydrase 4 working, the scientists found out that without a working sour receptor, fizzy drinks taste flat!

Why is it important?

Charles Zuker, who led this research, explained to the audience at the June 2009 Forum LIVE!  in Stockholm, the importance of understanding how our sense of taste works - without it we may eat poisonous foods and that may not be good for our survival!

Charles ZukerCharles Zuker

Action:

Try your favourite fizzy drink without the added carbon dioxide by letting all the bubbles escape before drinking it to see the effects of carbonation on taste... do you like it?

(Hint - use only half of your drink to do this - save the other half to drink the usual way with its bubbles of carbon dioxide to act as a control in your experiment. You can now compare the tastes with and without bubbles!)