Science - February 3, 2005

Humans smell sweet and savoury tastes

We not only use our mouths but also our noses to sense the basic tastes, salt, sweet, sour, bitter and savoury. Researchers at the recently disbanded research institute A&F have made this discovery.

Much of what we refer to as ‘tasting’ in everyday language has little to do with the mouth. According to scientists, tasting with the mouth is only done for the basic flavours sweet, salt and savoury. The rest of what we call tasting happens in the nose, as volatile substances in food are released from the food in our mouth and make their way through the throat to the sensors in the nose.

According to the A&F researchers the mouth does even less than scientists thought. Taste researcher Dr Jos Mojet had already shown that the sense of taste of elderly people works less well than that of younger people. That was news, despite the fact that it was already known that the elderly have a less sharp sense of smell than young people.

When Mojet repeated her tests, this time closing off the noses of the test subjects, she noticed that the difference between young and old disappeared for about seventy percent. That could only mean one thing: the sensory perception of basic tastes also requires the nose.

Mojet gave flavours dissolved in water to her subjects. During her experiments Mojet discovered that there is one important exception: test subjects, old and young, can hardly smell the savoury flavour monosodium glutamate. This is probably because MSG is found in quite high concentrations in saliva anyway, and the human nose no longer notices it.

Mojet published her findings in the January edition of Chemical Senses. / WK