On a recent September morning in Napa Valley, a sake-pairing session at the Culinary Institute of America's annual Worlds of Flavor conference began with a lesson in organic chemistry. The theme of the seminar was "sake and umami," a topic tantalizing enough to fill the room with food and beverage professionals who had traveled to the California conference from around the world to explore trends in gastronomy. Pens scratched notes furiously as Kumiko Ninomiya, of the Umami Information Center in Tokyo explained the science behind umami, the fifth taste, discovered by Japanese biochemist Kikunae Ikeda in 1908.

A fascination with umami has pervaded the food world for the past five years. Chefs are obsessed with it, food writers pepper their articles with references to it and the American hamburger chain Umami Burger spikes everything on the menu with umami-boosting seasonings.

But despite the ubiquity of the term, confusion remains as to what, exactly, umami is. The word describes the savory taste that comes from amino acids and nucleotides in foods such as fish, cheese, tomatoes and dried mushrooms. Unlike the other four basic tastes — sweet, sour, bitter and salty — umami is subtle, more of a feeling than a flavor. Imagine eating a piece of wagyū beef; the mouthwatering, tongue-coating sensation that follows chewing it, and the way that the meaty flavor blooms across the palate. Umami is the tool that allows your tongue to taste in three dimensions.