The question seemed so simple.

What does this broth taste like?

A Japanese chemist named Kikunai Ikeda asked himself that very question one day in 1907.

He was sipping a savory broth called Dashi, and he considered each of the four basic tastes in turn.

Was this broth sweet, salty, bitter, sour?

For 2300 years ever since Aristotle, that's how people thought about food in terms of those four elements.

Sweet, salty, bitter, and sour.

But to Ikeda, the Dashi broth did not taste like any of those things.

He could taste something else in Dashi beyond the usual quartet.

But what?

Then he remembered something.

A decade earlier, at age 35, Ikeda had been studying chemistry in graduate school in Germany.

Frankly, he found it hard to fit in there.

He struggled with the language and with the unusual customs.

But he enjoyed the exotic foods.

He ate strange things like tomatoes and cheese.

He could still remember the surprise of biting into them for the first time.

The memories were vivid.

And now Ikeda sense that his broth shared some quality with those German foods.

He wondered if there was some common element to them all, deep down.

It turns out that Ikeda was right.

Those foods did share something deep down.

...