What is Koji and how can it affect gut health?

yourWrapping a package of koji for the first time can easily make you feel like a professional chef about to take down the competition on a heated cooking show (or a kid on Christmas morning). After all, you’re dealing with an ingredient packed with umami goodness that will take your cooking skills from zero to 100.

What is koji, you ask? Well, it’s a safe to eat mushroom, also known as Aspergillus oryzae, which is traditionally used in Japanese cooking to make everything from sake to miso to soy sauce. It has also been linked to improving digestion, skin, and gut health. To learn more about the benefits of consuming koji, we spoke with several experts, including a Japanese food historian, registered dietitian, and culinary chef, for a comprehensive rundown on this fermented food. Also, a summary of how eating koji for a week affected my digestion and sleep: FYI, it was a 10 out of 10 in my book.

What is koji, according to a Japanese food historian

To learn more about the cultural significance of cooking with koji, we spoke with Eric Rath, PhD, professor of pre-modern Japanese history and dietary cultures at the University of Kansas. “Koji refers to a variety of molds used in fermentation…[it] it contains about 50 enzymes, and these break down the starch in grains like rice into sugars so they are available for yeast to consume in fermentation,” says Dr. Rath.

According to the professor, the product derived from fermented rice dates back centuries in Japanese history, to the 8th century, and is used to make many of the Japanese ingredients we know, love and consume on a daily basis today. “In Japan, koji is essential for making alcoholic beverages like sake and awamori, flavorings like miso and soy sauce, and fermented foods like traditional forms of sushi and pickles,” says Dr. Rath.

In recent years, chefs and food enthusiasts around the world have begun experimenting more and more with koji, as it’s an easy and delicious way to impart tons of umami-rich flavor to proteins and vegetables. and can also be used to cure meats. “A modern use of koji is as ‘salty koji,’ known as shio koji in Japanese, which is a mixture of salt, koji-infused rice, and water,” says Dr. Rath. “Many chefs and consumers are surprised at the many ways koji can impart sweetness and umami to foods.”

A registered dietitian weighs in on the health benefits of consuming koji

In addition to its rich history and delicious sweet and sour taste, know that koji is Really good for you. “Like other fermented foods, koji is beneficial because of the probiotics it contains, which are friendly gut bacteria that can improve digestion and overall health,” says Laura Iu, RD, CDN, CNSC, registered dietitian nutritionist. “It’s also rich in essential B vitamins, which are vital in skin cell regeneration, energy, and brain function.”

Iu explains that koji can be found in many different food products and is a gut-healthy way to add umami flavor to almost any type of food. “For example, common uses for shio koji are for marinating and softening proteins, while shoyu koji is a soy sauce that can be delicious in salad dressings. As a super versatile ingredient, koji adds rich flavor to plant-based dishes and enhances meat-based dishes,” he says.

As for who can (and should) eat this flavor-enhancing food, Iu says it’s been around for centuries and is a staple in Japanese cooking that’s considered safe for most people when eaten in moderation. Studies have also indicated that this ingredient contains a compound called glycosylceramide that works as a prebiotic that could be the connection between Japanese cuisine, gut microbial flora, and longevity. Although, as always, he recommends consulting a nutritionist to ensure that it is well suited to your personal needs.

How a professional chef recommends cooking with it at home

Christopher Arturo, Culinary Arts chef-instructor at the Institute of Culinary Education, has such a deep love for koji that he began growing it on his own in the school’s fermentation lab. With a balance of ingredients, science, and a lot of patience, Arturo discovered the best ways to incorporate koji into his daily cooking. He explains that humidity and temperature are two key elements that he must control when making koji from scratch.

In the lab, Arturo grows koji in a temperature and humidity controlled cedar chamber at about 85°F and 70% humidity, which allows mold spores to spread in the cooked rice. Although it can take him several weeks to grow, the chef enjoys making it from scratch as it gives him the freedom to control flavors more precisely and gives him access to the freshly made ingredient every time. Of course, he points out that if he’s short on time or doesn’t have the fancy equipment to do it yourself, he says he can find many excellent packaged koji products at Japanese grocery stores, specialty markets, or online. Looking for a high-quality product, Arturo says a good batch of koji smells like a freshly opened bottle of sake and has a “sweet funk.”

One of Arturo’s favorite ways to use this ingredient is flash dry-aging steak, where he uses shio koji as a marinade that transforms protein into a super-tender, umami-rich dish. “The koji is a super thirsty mold, and through the wonderful science of osmosis, it will continue to extract moisture from the protein so that it can drink,” he says. When this happens, Arturo explains that the mold undergoes an enzymatic reaction that breaks down the outer protein to form glutamate, which is one of the building blocks of umami, resulting in a sweeter, richer, and even tastier food.

Although making a koji-marinated tenderloin steak is Arturo’s way forward, he says he shouldn’t stop there. He has also experimented with pickling everything from bell peppers to cucumbers to plums using the transformative powers of the koji.

I Tried Eating Koji Every Day For A Week – Here’s What Happened

Growing up in a Japanese-American household, eating foods derived from koji, such as soy sauce and miso, was the norm. However, with limited access to imported Japanese foods in my hometown, koji alone was never something I used. Now, living in California, where there are specialty markets with much more accessibility to international ingredients, and thanks to overnight delivery on Amazon, getting a package of shio koji was more than easy. To really understand the benefits of this fermented food, I decided to take the advice of our helpful koji experts to try a variety of koji-infused dishes for a week. This is what I discovered.

First, my taste buds jumped for joy at the shio koji made with just four ingredients (rice, sugar, salt, and koji). I quickly realized what the hype was about. The paste had a nutty, savory, and slightly funky flavor, much like creamy salted butter mixed with a hint of miso-y spice. I used the product to marinate a New York strip steak, thinly sliced ​​pickled carrots, and roasted sweet potatoes. Each of these dishes was absolutely perfect. The shio koji enchanted each recipe with its enzymatic powers to create super-tender steak, tart yet sweet carrots, and luscious sweet potatoes. My favorite part? The absolute versatility of this ingredient. No matter the protein or the product, the koji imparted so much umami that I was on cloud nine all week.

Aside from my taste buds feeling great, my gut also benefited from this fermented food. Shio koji, which already has salt in it, meant I reduced the amount of sodium I used while cooking, as the product exudes flavor on its own. My gut felt well balanced and digestion was very regular, but maybe that was because I was so relaxed from all the good food I was enjoying.

Want more koji-infused fermented goodness? Look at this:

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