There's been a lot of talk recently about umami, the so-called fifth taste, alongside sweet, sour, salt, bitter.
The concept of umami was founded in 1908 by a Japanese professor who became interested in the delicious flavour that traditional Japanese seaweed broth gave to anything that was cooked with it. He discovered that the giant kelp, so popular in Japanese cuisine, was incredibly high in glutamic acid, the naturally occurring form of MSG. Glutamic acid gives food a richly savoury taste, a sensation that fills the mouth, harmonizing the flavours.
He named this taste umami, the Japanese for deliciousness. The second highest concentration of this free glutamate is in Parmesan, which itself is closely followed by sun-dried tomatoes and tomato paste: the simple addictiveness of pasta with a tomato sauce and Parmesan becomes suddenly obvious.