roasted coffee beans.

Why are they so delicious?

You might be surprised by the answer.

Science.

- Maillard reaction is a chemical reaction that's driven by the heating of amino acids and sugars and they combine into fairly complex molecules.

- [Narrator] It's the browning process that gives so many favorite foods their flavor, and it's somewhat of an obsession for Bob Florence.

- I'm a chemist by trade and I like mixing stuff together.

- Florence is a soy sauce brewer in North Stonington, Connecticut.

- Soy sauce is a very slow motion in Maillard reaction.

So think of browning a steak in a pan, that's quick, and where a soy sauce is taking me a year to take those amino acids and sugars and drive 'em together.

- His curiosity for Asian cuisine began decades ago.

- That was my first experience is hopping on a plane to go to Japan in my mid 20s, and I thought it was the most exciting thing that I could ever do.

- [Narrator] He would spend years traveling to Asia for business, and there, a passion for soy sauce was born.

- I started making it in my house.

I was making some small bottles of soy sauce and I started to sample them to local restaurants.

- [Narrator] But he had questions about the brewing process that only an expert could answer.

(K. Iida speaking in Japanese) - [Narrator] K. Iida is the head of his family business, Chiba Shoyu.

His company is located in Chiba province, home to 40% of Japan's soy sauce makers.

- He very generously agreed to meet with me in Japan.

- [Narrator] Iida says that when it comes to making soy sauce, mastering the first step is critical.

(K. Iida speaking in Japanese) - What we do is we take the soybeans and the wheat, and we sprinkle on this mold called koji mold or aspergillus oryzae, where there's probably a trillion little koji spores in here.

All right, well welcome to the koji room.

You'll notice how warm it is in here.

If it gets too cold, the koji won't grow.

If it gets too wet, the koji won't grow.

So you can see how it's got this little dusted white snowy look on it.

And that's actually the koji mold that's starting to grow.

By tomorrow morning, this will be completely covered in mold and it'll actually form a mat that won't be so easily broken up.

- [Narrator] It's a practice with a long tradition.

- There's two great fermentation cultures in the world.

One is yeast fermentation.

Everyone's familiar with yeast in terms of making beer and yeast grew up in Europe primarily 'cause it's cold and wet in Europe.

And so yeast as an organism thrived in that environment.

But the lesser known, at least to Americans, is this mold technology which grew up in Asia.

Asia's hot and humid.

The Chinese have been fermenting soybeans forever.

Around the 13th centuries, monks from China brought this technology over to Japan and the Japanese have then been optimizing their version of soy sauce ever since.

(gentle music) - [Narrator] Today, soy sauce has industrialized.

Most is made from soybean grits, soybeans that have been pressed for their oils.

But Florence still does things the old-fashioned way.

- If you were to start with half the ingredients, you probably end up with half the flavor.

And so by starting with whole soybeans, that oil contributes things like grassy, fruity flavors to the soy sauce.

So much more flavorful.

- [Narrator] Meanwhile, in Chiba, K. Iida that has had to work to preserve these old ways as Japanese tastes westernize.

(K. Iida speaking in Japanese) (K. Iida speaking in Japanese) - [Narrator] So when he heard from a certain American, it was a source of optimism.

(K. Iida speaking in Japanese) (gentle music) (K. Iida speaking in Japanese) - After you've grown the mold, you're going into a barrel of salt water, and then that barrel of salt water ferments for about a year.

- [Narrator] Today, after a year of fermenting, Florence presses his soy sauce mash called moromi.

It's also the name of his company.

He pasteurizes it by heating the soy sauce to kill any bacteria.

The process is a bonus opportunity for a Maillard reaction to make it even more savory.

(gentle music) These final few steps challenge this chemist at heart to take a different approach.

- My ultimate test is not like how much salt it is or how much pH it is.

(gentle music) But it's when I taste it.

It's got this whole character to it that is just a complete story for a flavor.

(gentle music) Okay.

- You can find Moromi soy sauce in restaurants