“Growing koji on meat” or “Coating meat with koji”?


Growing koji on meat or coating meat with koji? That is the question.

It seems like that growing koji on meat to mature it in shorter time is being global trend. Although it certainly stimulates my nosy personality, I have been wondering how it is different from simply coating meat with koji powder. Shouldn’t it work in the same way? And doesn’t it achieve the same effect in easier and safer way?

     I assume that the main purpose of growing koji on meat is to let it produce protease (protein degrading enzyme) during its growth and then let the protease work on meat to draw umami. If my assumption is correct, I thought I should be able to have similar, if not same, effect by coating meat with koji powder. So as an experimental freak, I decided to give it a go.

My first experiment (ribeye and fillet)

    I first purchased two pieces of meat, beef ribeye and beef fillet and coat them with soybean koji powder. I used soybean koji as it is much more protease-oriented than rice koji. I wrapped the meat with cling film and leave them to rest for a few days in fridge to see what effect koji has on them.

    However, I realised I have chosen a wrong portion! Ribeye and fillet are both softer and tastier portion and even without koji it is tasty anyway (so koji’s capability won’t be apparent). 

Coated with soybean koji powder
Wrapped in cling film
3 days later
Grilled for comparison
Soybean koji
Soybean koji powder

My second experiment - top side block

So let’s start again. In my second experiment, I purchased a top side block. I salted it lightly with shio-koji, coated them with soybean koji powder, wrapped it with kelp (as in Kobujime) and finally wrap the meat with cling-film to prevent it from drying. The idea is that shio-koji will draw water from meat, which helps soybean koji’s protease works better. Soybean koji’s protease should break the meat protein into amino acid which should increase umami flavour of meat. And then kelp piece should absorb water from meat and, at the same time, it should give plant- based glutamic acid (source of umami) to meat in exchange. Theoretically it should work, I think….. Finger crossed🤞🏻 I left it for 4 days. I made roasted beef and beef tataki with them. And it WAS VERY TASTY😍!!!


    Well, in order to make the objective conclusion, I know I should really compare the result No 2 with the meat grown with koji. However, I am too happy with the texture, flavour and taste of my tataki-beef from my experiment No 2 and I have completely lost my fighter’s spirit to move on….     So if there is anyone local who would like to continue my experiment I am happy to donate my soybean koji powder (comparison for control group)!
Wrapped with kelp piece
Still coated with soybean koji powder
Soybean koji powder scraped

Related Articles

The rainy season and plum works

Tsuyu, the rainy season in Japan, is translated as plum rain, because June is the time the plums ripen. The Japanese makes many kinds of plum preserves in this rainy season. I am introducing some plum preserves using koji.

Read More

scallop shoyu and fava shoyu

Two new types of shoyu recently joined in my shoyu collection♥
lovely scallop flavoured shoyu &
gluten free fava shoyu
In this post, these two are analysed.

Read More

What to look for in koji

Commercially available rice koji might look all same in appearance but the enzyme balance could be very different! Are they up to your intended use!?

Read More

Partially polished rice miso

I made very special miso today, which is a privilege as a koji grower. When you make your own koji, you can choose your own substrate and enzyme balance therefore you can design the taste and flavour of miso.

Read More

Koji sourdough bread

I am going to introduce a little trivia of the history of Japanese bread. Original form of Japanese bread made using koji! What is it different from western born bread?

Read More


Contents writer

The Koji Fermenteria Privacy Policy

This Privacy Policy describes Our policies and procedures on the collection, use and disclosure of Your information when You use the Service and tells You about Your privacy rights and how the law protects You.

We use Your Personal data to provide and improve the Service. By using the Service, You agree to the collection and use of information in accordance with this Privacy Policy.

The Koji Fermenteria Cookie Policy

This Cookies Policy explains what Cookies are and how We use them. You should read this policy so You can understand what type of cookies We use, or the information We collect using Cookies and how that information is used.

Cookies do not typically contain any information that personally identifies a user, but personal information that we store about You may be linked to the information stored in and obtained from Cookies. For further information on how We use, store and keep your personal data secure, see our Privacy Policy.

We do not store sensitive personal information, such as mailing addresses, account passwords, etc. in the Cookies We use.

Get in touch

Want to get in touch? We’d love to hear from you.

Latest News

11 May 2021

Will be back in Stroud Green

We will be back in Stroud Green. Koji natto, Pink shiokoji, Spicy soy dressing, Miso sesame dressing, Wild garlic pesto
11 May 2021

Koji for Life 6 copies remaining

Only 6 copies left in stock. Order now to avoid disappointment
11 May 2021

Koji starters restocked

Premium koji starters from Hishiroku restocked - 40 bags for rice and 20 bags for protein substrates

Koji Making - Online

The online koji making class takes place over the span of 10 days. The class structure is as follows.

Day 1       Guidance session (Zoom 1 hour):

What is koji?   Koji making overview Tools & equipment required

Day 7-9 Practical (Zoom & Facebook Live):

Day 7  Steam Inoculation Zoom 4 hours) Day 8  Mixing (Facebook Live) Day 9  Drying(Facebook Live)

Day 10     Wrap up (Zoom 1.5 hour)

        Review, Troubleshooting, QA         Koji application

Keep up to date for new dates ?

Stay in touch !

Stay up to date with our latest news and get notified with new event?