According to today's Chicago Tribune:
Chefs, nutritionists, cookbook authors and food processors are salivating over the merits of umami, the "fifth taste" that is neither salty, sweet, bitter nor sour.
. . . for food processors, boosting umami levels in their products could mean less reliance on salt, or more-palatable low-sodium products.
. . . Umami — pronounced "oo-MA-mee"—comes from a Japanese word meaning "deliciousness." This somewhat elusive flavor shows up in a wide variety of protein-rich foods.
. . . This savory taste was isolated 100 years ago by Kikunae Ikeda, a Japanese scientist who wanted to figure out what gave dashi, a Japanese seaweed soup, its distinct flavor. He concluded that the umami flavor came from glutamate, an amino acid and protein building block.
That means protein-rich foods like meat and dairy products tend to be high in umami, especially when the cooking or processing of the foods gives the proteins time to break down into glutamates. Curing, aging, browning and slow-cooking enhance the umami taste of those foods.
Although the concept has been around for a century, the fifth taste has been slow to catch on in America and other Western countries. For starters, there's the name, a strange-sounding foreign word.
. . . Chefs are increasingly incorporating umami flavors into their recipes. New York's Jean-Georges Vongerichten makes a custard with Gruyere, goat and Parmesan cheeses, topped with shaved black truffle. He calls it "an umami bomb."