When I was at school, I was taught that there were four tastes - sweet, sour, salty and bitter. We learned that the tongue is divided into four sections, each of which could sense a particular taste - the tip of the tongue was for sweet, the sides responded to sourness, etc.

It seems that everything I was taught was wrong. It is now accepted that there is a fifth taste - umami. It sounds like something Vic Reeves would shout on Shooting Stars, but it is the Japanese word for glutamate. It was discovered by Professor Kikunae Ikeda of Tokyo Imperial University in 1908, but it has only become accepted in the west in recent years.

So what does Yo Mama taste like? Well, it's hard to describe - it's a sophisticated flavour found in asparagus, oysters, mushrooms, shellfish, seaweed, and is sometimes described as 'savoury', 'earthy' or just plain 'delicious'. It is the taste of protein [which immediately leads me to identify the taste in - oh - you know. Ooh mummy!]. Umami, or glutamic acid, is one of the 20 amino acids of which proteins are built.

And now new research has emerged which suggests that the tongue is not divided into specific taste areas at all. "It's a myth that has perpetuated and is still taught at schools and universities," says Professor Laing, director of the Centre for Advanced Food Research at the University of Western Sydney.