Why does orange juice taste disgusting after I ve cleaned my teeth

A.� This phenomenon, known as 'the orange juice effect' has been widely studied.

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The nasty flavour is caused by the detergent added to toothpaste. The detergent, the most commonly used one is sodium lauryl sulphate, produces the foam that we are used to when brushing our teeth.

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Q.� Why should a detergent affect how I taste things

A.� Because the active layer in our taste system is a phospholipid layer. Detergents interfere with the way lipids work, so that when you brush your teeth you temporarily loose the ability to taste sweet things. Additionally anything that normally tastes sour tastes really bitter instead.

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Oranges contain a fair bit of citric acid, which has both a bitter and a sour taste. So, after you've cleaned your teeth, you loose the sweetness of the juice, leaving only a very bitter taste in your mouth.

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Q.� Why is detergent added to toothpaste

A.� Mainly because it foams when you brush, acting as a visual signal to us that the toothpaste is doing its job.

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Q.� Does the detergent just effect the taste of orange juice

A.� No, it can affect the taste of most things for anything up to two hours afterwards.

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Do you want to know how something affects our normal sensory perceptions Just click here to ask.

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by Lisa Cardy