Friday, April 15, 2016

Koji-Rubbed Steak – New Age Dry Age

First, let me give credit where credit’s due; and by “credit,” I mean possible blame. I got the idea from this article in Bon Appetit, where they showed how to use koji rice to simulate dry aging a steak. They say they borrowed the idea from Trentina chef, Jonathon Sawyer, and we’ll take them at their word.

Anyway, I tried it out, and had mixed results. The smell and flavor were vaguely reminiscent of dry-aged beef, but it didn’t have those same cheesy/funky/earthy background notes. As far as the texture goes, there was no difference from a regular steak, and it may have even given it a somewhat firmer texture.

That may have come from letting it go almost three days, instead of two, but hey, I was within the range. Besides, I’m not even sure anything happened. The idea here is that the fungus on the koji rice, which breaks down the proteins in beans, to make things like miso, would work the same magic on a steak.

While it did look like the koji had “bloomed” a bit, and there was more “white stuff” at the end of the process, there was no obvious signs that the meat had been “broken down.” The appearance was darker, and it kind of had that waxy look of dry aged meat, but that could’ve simply come from sitting uncovered in the fridge.

I found it a bit suspicious that there were no other posts regarding this online, but maybe it’s just too new. Time will tell. I'm looking at you, food blogger. In the meantime, any and all feedback is welcomed, especially if you are familiar with using koji rice. I’m not sure if you should give this a try, but, as always, enjoy!

koji rice (I used this one)


Unknown said...

Hmm maybe bigger grains result in less adhesion and less surface area, making the dry-aging process less effective and therefore slowing down the process?

This looks interesting though.

Evan said...

I think you were looking for this.


Unknown said...

I am glad it didn't ruin that beautiful set of steaks you had. Being from the Midwest I will be taking your advise and not trying this.

Thanks for "taking one for the team" Chef John

Unknown said...

Very interesting - I've found similar findings from salting a steak 24-48 hours in advance. The surface moisture has been drawn out to yield a better sear at the expense of some loss of tenderness. I am sure that the way to run further tests would be to compare powdered vs. mortar/pestle and see how steaks of various days of "aging" stack up - though in all honesty, I get the impression that the linked article is overselling how closely the steak mimics dry-aging. Maybe give it a shot on some pork chops since we tend to expect those to be a little bit firmer due to the higher temp?

claritas et obscuritas said...

To say the least, it is a very unique way of using koji rice, which should be fermented with salt and water. Google search "shio koji" or "salt koji" for more information.

Unknown said...

Hey John, thanks for the article + video. I love your channel, especially for your honest opinions if something didn't work. Unfortunately, in this case I have to try this anyway - sounds super cool.


Frank said...

Nice review, Chef.
I don't think I will be trying this one.
I love steak. I spent the money once to try a dry aged steak from my butcher and I did not think the extra money spent was worth it.

Jeremy said...

Hey John!
I loved your video. I'm sorry your results didn't turn out as you hoped. Next time use the spores of Aspergillus oryzae instead of the pre made koji-kin. You'll obtain the results you're looking for. I work extensively with koji and can happily answer any questions that you may have about the technique. Check out this TED Talk about the technique:


Unknown said...

Also consider checking out the reverse sear method as popularized by Kenji from Serious Eats - the premise behind it being that you slow cook a thick piece of meat in a low temp oven until it comes close to your desired internal temperature and follow that with a finishing sear. This has actually become my go-to method for steaks and chops; bear in mind that I do not have access to a grill or sous vide. I think the big benefit of this method (besides a consistent internal temperature in a thick steak) is that it dehydrates the surface slightly to yield a better sear without having the curing effect as noted by overnight salt/koji/etc. treatments. With that said, the smaller timeframe it spends on the cast iron yields less fond for a pan sauce - but life's all about compromise right?

Unknown said...

Total waste of time, Chef John. If you have the money to spend, then spend it on a nice cut of prime beef. Leave it uncovered on a baking rack in the fridge for a day or so to reduce the moisture content.

When ready to cook, pull it our of the fridge and let it come to room temp - about 1 hour. Season with salt and pepper and grill/pan fry/broil to the desired doneness.


Chris K. said...

Article from SF Gate in 2013 about koji and shio koji. It includes supplier information and several interesting recipes:

Unknown said...

Oh Chef John, if that's the ponytailed bearded guy from the video speaking to you, please let him guide you into another try, that would be so awesome.

Annie said...

Chef John - Just recently discovered your wonderful blog. I am slowly working my way through a couple at a time. I'm loving your no-nonsense approach to some classic dishes. A bit of a food show junkie, I've been watching them since back when Graham Kerr was Galloping into our foodie lives.
As far as steaks go, I'm bemoaning the fact that it's damned hard to find a nice simple bacon wrapped filet these days. How is that, in the midst of all this bacon frenzy in the food scene?
Thanks for the videos. Slainte. Judith

doctorbeer said...

In addition to the partial decomposition of the meat, dry-aging also results in significant evaporation of water in the meat, thereby concentrating the flavor. I'm not sure that two days in the refrigerator accomplishes that. A good experiment might be to coat just one steak with the koji, leave the other one plain, and age them and cook them the same?

mekman said...

We home age all our steaks by sprinkling garlic salt OR steak seasoning OR just plain salt and pepper. Put them in the (less used fridge) uncovered for 24-48 hrs, we have never been disappointed with flavor texture or appearance (and we always cook them on coals) blah propane!

aiko said...

You did it completely wrong. You didn't even read the instruction on the back of the back, did you? You are supposed to make salt brine with dried Koji, that takes 7-10 days to culture depending on the weather and temp. End result is white slurry with bits of rice which you can mush with your fingers soft. If you feel hard bits in between your fingers, it needs to culture some more. You can keep the end product in your fridge. It lasts months and you only use a little bit to marinade your meat anyway.

Horrible way to waste a good bag of Koji. I'm upset and disappointed.
Get somebody who can read the instruction to you and do it right the next time! Hate when someone just wings it. Shame on you.

aiko said...

You are supposed to make salt brine with Koji. Takes 7-10 days to culture, depending on weather and room temp. Culture until soft, you can mush with your fingers soft. If you feel hard bits still, culture some more days. End result is white-grayish slurry. Keep in fridge, lasts for months. You use a table spoon or two to marinade stakes like that. I hand blend mine so that it's smooth, easy to use.You wipe away the excess before grilling or pan frying. Koji, naturally made from rice grain. It will burn like any other starch.

Very upset you didn't do it right. You didn't even read the instruction on the back of the bag. You just winged it. Shame on you. You are in a position of introducing foods from different culture. At least get someone who can read the instruction to you. Very very disappointed with your poor decision. You are located in a place where there are many Japanese around, no?

Do it right the next time. What a waste of good stakums... Better to use on chicken, or pork anyway.

Unknown said...

I make salt-koji at home and marinate meat all the time. I really can't describe the taste, but it's just a lot better than just sprinkle s&p. Also, meat doesn't spoiled easily. Downside? I have to plan ahead... The article is awesome and helpful, Chiris K.

Chef John said...

Aiko, Thank you for your lovely comments. We were NOT trying to use the koji as directed on the package! We were testing an online story about dry-aging using a powder made from the crushed koji. That is why it was not used with water and salt.

aiko said...

sorry, i seemed to have sent my message twice.
Dried Koji obviously is barely active as culture, comes alive room temp with lots of moisture.
Never really in fridge temp, it is a living thing.
Won't do anything to anything if its dry and cold.
If that's what you were trying to prove, then, my bad.
Your experiment was successful.

Unknown said...

I read the article, but it says "Before cooking, rinse the meat thoroughly in cold water to remove all the koji rub that has become a paste, then pat dry." Using water may be given you a different result...?

Daryl said...

Chef John, I prepared this recipe a couple of days ago (I ordered the koji the day of your post and it took about 5 weeks to receive it, from Japan). I pulverized the koji in a food processor to a powder as stated in the Bon Appetit article, coated the steaks (tenderloins) really well, aged them on a wire rack for 2 1/2 days, rinsed them with cold water, and dried them before cooking. Results? Well, similar to yours. They were good, but not better than good. While it was fun doing it differently, I won't prepare steaks that way again. It isn't worth the trouble.

Unknown said...

I honestly haven't tried the dry koji rub yet. It looks interesting! I don't mind the hard texture.

I used the shio koji before to marinate beef. The stir fry beef came out extremely tender and tasty. I did marinate it for a couple of days in the fridge.

Mind you I make my own shio koji from scratch. Started with raw organic white rice...long process but definitely worth it.

IsobeFood said...

Chef, check this method from Cooks Science.

Could perhaps be a way to prep the meat prior to your dry aging process. Any idea if that would work?

Unknown said...


I recently did a spatchcocked turkey rubbed with a salt/ground koji mixture, based off of Bon Appetit's Koji Roast Chicken recipe. I had similar results in that I really couldn't tell the difference between this turkey and any other years'.

I think the above commenter might be right, that using a shio koji brine might be the best way to use koji (I haven't tried it myself, but I trust that they seem to have been pretty thorough in their testing.

Unknown said...

You can't dry age a steak, only whole cuts of beef!

See here for explanation

Try this again with a prime rib roast and the flavor will curl your toes.

Unknown said...

Chef John, I think this may be made better if you added some water and salt to the koji, as well as grinding it up. I know a good deal about fungus, this will help it colonize the meat more.

Check out this article:

Larry Jr. said...

Do you think the meat needs to be exposed to air or can it koji-age wrapped in plastic?