Humans have a 5th taste other than sweet, sour, salty and bitter. It’s called ‘umami’ which means ‘delicious’. It was discovered by a Japanese chemist Kikunae Ikeda after studying the taste of dashi- a Japanese soup made from seaweed.
"Umami" has long existed in our food but was not fully known until Japanese chemist Kikunae Ikeda formally identified the "finger-licking" taste. The reason why it took so long to be discovered is because the taste was neither sweet, sour, salty, bitter nor any combination of the four, the taste is also not as obvious as other tastes and may require some training. Scientists didn't think it was a real taste but rather "all in the head". As Ikeda tasted the soup, he noted a "common taste of tomatoes, cheese and meat" but he could not identify any of the four well known tastes. As a chemist, he went into his lab and found the secret ingredient. He wrote in a journal for the Chemical Society of Tokyo that the taste was actually of glutamic acid. It was however renamed "umami," in his honour, which means "delicious" or "yummy" in Japanese.