You've probably seen Chinese restaurants touting their food's MSG-free status. You may have even noticed strange symptoms after eating food you suspected had MSG. What is this strange ingredient, and why is it so vilified?
At the turn of the 20th century, a Japanese man named Kikunae Ikeda noticed something interesting about the dashi broth his wife used in her cooking. There was something to it that was unlike the four basic tastes we knew about. Luckily, Ikeda was a chemistry professor at the University of Tokyo, so he quickly got to work studying and isolating this mysterious flavor from the kombu seaweed that formed the basis of the broth. What he created was the molecule C5H9NO4, or glutamic acid—the compound responsible for the new flavor he coined umami, from the Japanese umai, or "delicious". By adding salt, he was able to turn the molecule into a more stable, granular substance that could be sprinkled on food, and monosodium glutamate (MSG) was born.