Sweet, sour, bitter, salty — and umami. In 1908, Professor Kikunae Ikeda of Tokyo University identified the material he isolated from a kelp broth as glutamic acid. He found that its salt monosodium glutamate (MSG) gave an enhanced and meaty flavour to vegetable dishes and he named the crystals umami (Japanese for savoury or meaty).
What is curious about monosodium glutamate is that it does not add a specific taste of its own, as does salt. Instead, it seems to increase the sensitivity of taste receptors thus “multiplying” the natural flavour of meat and vegetables. But it does not have the same effect on fruits, sweet foods or eggs.
Mushrooms contain a large number of proteins based on glutamic acid and this might account for their slightly meaty flavour and the fact that they are often served with meat dishes.
Umami is the taste of protein in meat, cheese and fish. The importance of protein in our diet means that it makes sense for umami to create a pleasurable sensation in the brain, unlike bitterness, for example, which indicates danger.
Umami was only confirmed as the true “fifth taste” in 2000, when researchers at the University of Miami reported their discovery of a protein receptor on the human tongue. A mature, robust red wine has the umami taste.
The Ajinomoto (“essence of taste”) company was formed to manufacture and market MSG in Japan and the taste-enhancer remains the company’s signature product. It is now produced by the large-scale fermentation of starch or sugar.
Chinese restaurant syndrome (Kwok’s disease), with its mildly unpleasant symptoms of numbness in the neck, arms and back, weakness and palpitations, was traced to extravagant use of MSG by some Chinese chefs. It does not affect a large percentage of the population and has been relegated to the status of urban legend.
In fact MSG is more of a solution than a problem: if used as a replacement for salt it is possible to reduce sodium levels while still enjoying a tasty dish.
