If your rice is covered in mold, it’s garbage, right? Or is it?

That depends upon the mold. If it’s aspergillus, you’re probably onto something good.

Aspergillus is a fungus whose spores are present in the air we breathe. And, rice that is inoculated with aspergillus becomes koji ─ the essential fermenting agent for making miso, a staple in Chinese and Japanese food cultures for thousands of years.

What is Miso, Really?

Traditionally, miso is made from fermenting soy beans. Once the peas and koji are combined with water and salt, the mixture is shaped into balls, pressed into a crock, covered and stored for years at a time until it is ready to use.

From a health standpoint, miso and other fermented foods such as yogurt and sauerkraut are rich sources of probiotics that enhance digestion and improve gut health.

The process of preparing hand-made miso hasn’t changed much since its ancient origins, except now you can buy packaged koji on Amazon.com, and you have the help of time-saving kitchen gizmos like an Irinox® blast chiller to quick chill the miso mixture, and a Pacojet® processer to whiz it into a silky smooth paste. “This is where ten thousand years of tradition meet ten years of equipment,” said Culinary Vegetable Institute Chef Jamie Simpson.

Tradition aside, Chef Jamie said you can miso just about anything.

TCG: What are you using today?

JS: Carolina Gold rice and Sea Island red peas, both from our partner Anson Mills®.

TCG: So, what is koji, exactly?

JS: It’s a firm, granular aspergillus grown on wet rice, then dried and packed.

TCG: What else have you miso-d?

JS: We did celery root and white soybean. We did pine nuts.

TCG: How long did it take until you could use it?

JS: It took about a year, and then lasted about three years.

TCG: Besides soup, which pretty much everyone has heard of, how else can you use miso?

JS: You can use it for marinades, rubs, sauces. It’s added as a glutamate to a lot of things.

TCG: Glutamate?

JS: That umami taste.

TCG: How long did you ferment the batch you’re using today?

JS: We made it December 12, 2016. So, a little over two years.

TCG: When you took off the cover, it was moldy and, frankly, it looked pretty gross.

JS: You have to cover the surface to inhibit surface mold, but you’re always going to get some. But it’s not like black mold.

TCG: Is it safe to eat, even after you’ve scraped it off?

JS: Of course.

TCG: It seemed like you put a ton of salt into it.

JS: In China and Japan, they originally used salt to preserve it. Then the aspergillus did what it does, and it just got better over time.

TCG: Is it supposed to be super salty?

JS: It won’t be. When all of the sugars come out of the beans, it’s balanced.

TCG: How do you know when it’s ready to use?

JS: If you open it too soon, it smells like fingernail polish.

Red Peas and Rice Recipe with Miso Butter

8 oz. (234 g.) Carolina gold rice

1 ½ c. water

8 oz. (234 g) Sea Island red peas

2 ½ c. water

9 T. salt

2 ½ c. koji

1 T. existing unpasteurized koji

8 oz. water