Maybe you’ve heard about the famous 45 days aged steak. It’s known for its tenderness and its interesting funky flavor. Just as described by the name, this steak is aged for 30 to 45 days in a sterile storage with controlled air-flow, temperature, and humidity to enhance the texture and taste.

The only downside to 45 days aged steak, is that it takes a long time to make and usually quite expensive if you buy it in the market.

But, did you know that you can rapidly dry age a steak for 48 hours with rice koji? It’s easy to make at home and it only takes two ingredients: a piece of steak and rice koji powder.

First Of All, What Is Rice Koji?

Dry Age Steak With Koji Rice

Rice koji is a steamed rice grain that’s been inoculated and fermented with koji mold. Rice koji is a traditional Japanese ingredient that is used to make all kinds of things like miso, soy sauce, sake, mirin, and many others.

Koji is also propagated on all kinds of ingredients other than rice, including wheat and beans. These variants of koji will have different taste profiles.

Read more about koji here:

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What is Koji? Introducing the Kinds of Koji and How to Use It
Koji is an indispensable word when talking about Japanese fermented food. You can't finish making Japanese fermented food, such as miso, shoyu, mirin, sake, etc., without creating the koji as its first step. This article is about the complete guide about koji and everything you need to learn about it. Let's dive further into the Japanese fermentation food culture!
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Koji rice is steamed rice that has been propagated and fermented with koji starter. You can use koji rice into various foods!
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Shio Koji is not uncommon in Japanese cooking. In fact, its rustic nature goes beyond oriental cooking and successfully made its way into western cooking. Learn how to include this special ingredient into your everyday meal, explore what constitutes shio koji, its versatile uses and for those who’d like to try it hands-on, shio koji making at home!
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Getting To Know Rice Koji Steak

Dry Age Steak With Koji Rice

Rice koji steak, or koji beef, is a steak cut that is aged using a rice koji rub. Aging your steak with rice koji will shorten the time process. Using koji, you can rapidly age the steak only in 48 hours. The powerful enzymes that reside in koji will help tenderize the meat and add a special flavor reminiscent to 45 days aged steak.

Of course, rice koji steak won’t have the exact result as a 45 days aged steak. You can say that rice koji steak is a completely different style of steak altogether. Compared to the regular technique, rice koji steak won’t be as tender as 45 days aged steak. But, it will have a sweeter aroma from koji that makes this steak a totally different thing.

So, is it worth the hassle to do?


Though koji rubbed steak may not have the same taste compared to regular dry aged steak, koji steak is still great cooking to try. Koji powder will add a hint of sweetness to the steak and it will be an interesting experience. Besides, it only takes around two days to completely age a steak with koji and the process is really hard to mess up.

The Characteristics of Koji Aged Steak
Sears a lot faster on the surface
Slightly sweet aroma
Tender, but not as tender as 45 days aged steak

How to Dry Age Steak With Rice Koji

There are a few techniques on how to apply rice koji on the steak. Some suggest using the paste version of koji instead of the dried ones. There is no wrong technique, it’s just a matter of preference. For this tutorial, we’ll use the dried powdered form of rice koji.

The difference between using paste rice koji and powdered rice koji:

Paste Rice Koji Powdered Rice Koji
If you want to use paste rice koji to age your steak, you can use fresh rice koji or dried rice koji that has been rehydrated.

The koji texture will be more moist and pasty.

After you apply paste rice koji to the steak, wrap the steak with cheesecloth to keep the paste stay in place.

Age the steak the same way as using powdered rice koji.
Powdered rice koji is dried rice koji that has been pulverized.

Using powdered koji to make koji beef is actually easier to do since you don’t need to wrap the whole thing in cheesecloth.

STEP 1 Prepare the powdered rice koji

Use rice koji powder so the koji can be absorbed thoroughly.
You can find rice koji powder here. If you don’t have rice koji powder, you can use dried rice koji. Blend dried rice koji in a blender or food processor until fully powdered.


STEP 2 Rub the rice koji powder on the steak

Sprinkle liberally all over the surface. Make sure to fully coat the steak and pat it in.


STEP 3 Dry age the steak for 48 to 72 hours.

Put the steak on a wire rack. Let it uncovered to dry age in the fridge for 48 to 72 hours. By using a wire rack, it will be easier for air to circulate to the bottom part of the steak as well.


STEP 4 Scrape the rice koji powder and cook the steak

After letting it age for 48 to 72 hours, the koji on the outside of the steak should look darker.

Scrape and rinse the rice koji powder from the surface of the steak and cook it on a frying pan. Just add simple seasoning like salt and pepper, we don’t want to overpower the rice koji flavor. You can also sous vide the steak first, before searing it on the frying pan.

Rice koji steak sears really fast. This is caused by enzymes in the koji that break down starch and protein into sugar, making the surface of the steak all caramelly and delicious. Make sure to adjust the heat so the surface won’t burn too quick.


Tips On Aging Steak With Rice Koji Powder

Age the koji rubbed steak in a cool and clean place. If you make it at home, you can use the fridge.

Rinse the koji from the steak before cooking. Or, you can also scrape it with the back of your knife. Leaving the koji crust on the surface is not wrong per se, it’s just gonna sear faster on the frying pan. This will cause the surface to char faster before the meat inside is fully cooked.

Avoid aging rice koji steak for more than 2-3 days. Aging the steak for too long may result in tougher meat.

Do not overseason the steak when you cook it. Dry aging with rice koji will result in an already flavorful piece of steak. So you may want to avoid overly salting your cut when you cook it. The best way to enjoy this steak is to avoid adding multiple herbs and seasonings other than salt and pepper.

Frequently Asked Questions

Can you replace regular dry aging with the rice koji technique?
No. Both are unique in their own way. And even though somewhat similar, they are not interchangeable.

Rice koji aging won’t result in the same taste and tenderness of 45 days aged steak. Due to the natural aroma of koji, the rice koji aged steak will also have a hint of sweetness and a delightful flavor profile. So all in all, they can be considered as two different things.
Does the rice koji powder tenderize the meat?
Yes. Though it might not be as effective as the 45 days aging technique. But aging the steak in rice koji powder can do pretty good in the short time period.
Can I use chicken instead of meat?
You can, but we don’t recommend it. It’s not impossible, but it may be too risky to let chicken meat out for days in the fridge.

To make a flavorful chicken with koji, we recommend marinating chicken in shio koji (salt koji).
What to do with koji rice powder besides making steak?
Using powdered rice koji, you can make all kinds of things like amazake, salt koji, and others. You can also mix rice koji powder when you make bread or cookies.

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