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Making Koji for Homebrewing Sake - The Taylor-MadeAK Way
10/17/08
09:05:26 pm by Bob Taylor, Categories: Homebrewing, Sake , Tags: homebrew, homebrewing, koji, koji-kin, kome-koji, sake, tane-koji The Coup de Grâce
I've saved the best part for last. Are you ready for some information you can't get anywhere else? This is the coup de grâce for the secret that every kura worldwide has so jealously guarded over the centuries that information regarding it is not available anywhere on the English-speaking or Japanese-speaking internet (I asked John Gautner to look on the Japanese side for me and even ask his toji friends). The one thing that the people who make money from koji and related products (especially Vision Brewing) does not want you to know.
This is the answer to the question that I often receive, of which this is but one example:
Comment from Forrest O. [Visitor]
Here's a question for you, can you make koji from some of the last batch of koji, instead of koji-kin?
An infinite supply of koji to fill your sake homebrewing requirements, for nothing more than the cost of your first pack of spores and the rice you put into making it? Hmmmmm....
Yes, it can be done! But not in the way that our friend Forrest here is assuming. It needs to be understood that koji, while being a fungus, is not yeast. It's not possible to culture more of it by simply mixing some of a previous batch of koji with some steamed rice. It won't spread kernel-to-kernel like that, it's just not how it works.
But, in my scouring of the internet in search of any information on the subject of harvesting koji-kin spores, I found one very brief, very obscure (so obscure that I can't re-find the document to link it here, I'm relying on my memory) reference to the old traditional Japanese method of inoculating freshly steamed and cooled rice with aspergillus oryzae spores. With that little scrap of information, some educated guessing, and a little luck, I figured out how to replicate that technique.
And now I'm going to tell you how I did it.
Equipment
I know, I know, there's already a huge list of equipment back at the beginning of this guide. But I'm mentioning this here because there's one particular item that you may not have around the house, and you'll want to make sure you pick one up. I'm talking about a good size shaker with small holes on the top. I grabbed this beauty at Wal*Mart for about $3.50 specifically for this task. You need to make sure that whatever shaker you use has small enough holes on it to prevent the rice grains from falling through, which means a pizzeria style cheese shaker is not appropriate unless you modify it with some kind of screen under the lid. You just want to be able to shake koji-kin spores out of it without the rice grains that is their source falling out.
You'll also need a small bowl or some other vessel to hold a small portion of your koji rice. Hopefully you made more than you needed for your upcoming batch of sake.
Method
This is actually very simple. As near as I can tell, two major factors trigger aspergillus oryzae into its spore-producing state: full maturity (time) and dehydration. Once the 40-50 hours of main incubation of your batch of koji is finished, take a small amount of the kome-koji (I used 1/4 cup, but this is a very small amount for experimental purposes), separate it from the koji you're about to refrigerate or freeze, and put it in a clean plastic bowl. This bowl you just move back to the incubator, which hopefully is still warm. Take out the cup of water or whatever other means you used to keep the incubator humid, leave the bowl of koji rice uncovered, put your temperature probe in the bowl, and seal the incubator back up.
The residual humidity inside the incubator is enough to keep the rice from drying out just long enough for the aspergillus oryzae to figure out that things are getting arid and prepare to start reproducing. In 24 hours, you'll have something that looks like this:
See the green splotches forming all over the place (more evident at the edges due to lower light intensity)? Spores! Carefully stir the grains up a little bit to separate them, but don't be too rough or you'll end up with a cloud of spores instead of nice green-covered grains. Place the bowl back in the warm incubator and check on it in another ten hours. Chances are, you'll see something like this:
Don't stir or otherwise disturb those grains or you'll get a face full of spores. Just leave the bowl where it is and come back to it in 10 to 12 hours. When next you see it, there may or may not be a big visible difference:
Grains of rice covered in yellow-green spores. This yellow-green color is the only exception to the "white-only" rule of making koji.
Provided that you did, indeed, remove the humidifier from your incubator, this tane-koji should now be dry enough to move to its final resting place. It might be prudent to consider using a piece of cellophane to cover the openings of both containers while you pour the tane-koji into the receiving vessel, just to prevent any spores that get knocked loose from flying all over the place (they're very fine, smoke-like when they become airborne):
The rice and its accompanying mold will dry out further over time in this shaker, and will keep pretty much indefinitely at room temperature. This shaker came with a plastic lid that fits over the top, which is pretty nice to keep contaminants out. If you don't have one, you could cover it with some plastic wrap and secure with a rubber band when not in use. To use this, just remove whatever cover there is from the holes, invert, and shake over the rice you wish to inoculate. Mix and repeat until you are satisfied that you've gotten enough spores into your freshly steamed rice - it's not really possible to overdo it with the spores, but not adding enough might be a concern. You want the inoculated rice to have a noticeable green tinge to it when you're done, which usually takes three applications of spores when I do it.
...And In Conclusion...
As I have herein shown, the process of growing your own koji from readily available mail-order (okay, internet-order) spores should be pretty clear and easy to follow successfully with only a few basic pieces of equipment necessary to maintain the proper environment. It's somewhat labor-intensive with all the stirring, but no more so than sake itself is. And hey, making your own sake utterly from scratch is worth it, right?
Additionally, with the knowledge that koji can be encouraged to spore and be used in the old-school Japanese style to inoculate further batches, your first pack of spores should also be the last one you ever need to buy.
Thanks for reading!
-]Bob Taylor, Taylor-MadeAK
69 comments
Comment from: shelley [Visitor] 
Your article is great! I just finished my first batch of koji and was looking for some photos to confirm mine is "ok". Thanks for the pictures! I used an electric roaster with a couple inches of water to create a warm, moist growing environment and it worked well, although required constant temperature monitoring.
Looking forward to starting the next step tonight!
10/21/08 @ 08:56
Comment from: Nick [Visitor]
What are the ideal temperature and humidity conditions for koji growth and sporulation?
11/02/08 @ 17:49
I'm sorry, Nick, I just don't have numbers to answer your question with. The only people who would have those numbers are professional sake producers, and they just aren't known for their habit of giving out trade secrets to homebrewers like me.As I wrote in this guide, I kept the inoculated rice in the 86º-88ºF range throughout its entire time in the incubator, but after 30 hours the temperature started rising past 90ºF very quickly as the mold kicked its metabolism into high gear. After 45 hours I called the koji "done" and moved the bulk of it to my freezer, but in the name of experimentation I left some in the incubator.
To encourage the mold to sporulate, I left the temperature controller set to where it was and removed the cup of water I was using to keep the humidity high, but did nothing else to encourage drying. Whether or not this is actually necessary I can't say because I've only done the experiment once. It's possible that the only factors that aspergillus oryzae needs to sporulate are high temperature and time - humidity, or the lack thereof, may be irrelevant to the mold reaching maturity once it has metabolized enough of the rice starch.
11/02/08 @ 19:01
Comment from: Michael [Visitor]
Greetings from Denmark,I do really admire your work,sir, and I appreciate your focusing on the enzymatic saccharification potential of the fungus Aspergillus Oryzae. I ordered 1 sachet of Koji-kin from the Australian Company
http://www.tibbs-vision.com/sake/
one year ago and I managed not only to propagate a spore culture on steamed rice but also on steamed wheat and quinoa kernels. I do sincerely recommend you also to seek out the possibilities in using koji-kin to produce your own homemade soy sauce (sho-yu), miso or even unmalted beer. I just recently started creating a Blog concerning these matters, so I look forward to reading more from you.
Kitchen laboratory experiments make great fun!
11/16/08 @ 10:26
Comment from: Harry Jarvis [Visitor]
Hi Bob,I am about to start my first batch of Koji (and, eventually, sake). I am confused about the length of soaking time for the rice. You have called for 18 hours all over this site, but above her, you add this addendum:
I'll update the rice-steaming instructions with this information later, but I timed this particular batch of rice while watching for the aforementioned volume increase: It took just over one hour. That's for regular old Kokuho Rose rice, not some fancy highly polished sake rice. Soaking another batch of rice overnight didn't produce a noticeable increase in volume, but it did result in steamed rice that stuck to my hands tenaciously, where the batch soaked for only an hour did not. So, there you have it: rice being prepared for steaming only needs to be soaked for an hour to absorb the necessary water, not overnight.
Are you changing the amount of time required for ALL soaks, just this pre-Koji soak, or am I not understanding?
Thanks,
Harry Jarvis
01/29/09 @ 13:51
I know the differing soak times are confusing, I really need to update the original sake making guide but I've been putting it off because I haven't been able to figure out how to update that information without generating even more confusion.Here's what happened: I did quite a bit of research on the matter of soaking rice prior to steaming for any step in the sake making process, and the only consistent answer (where I could find any answer at all) was that soaking time doesn't matter all that much. What does matter is how much water the rice absorbs, which for steaming means 25-33% of the rice's original volume or weight in water.
That makes sense, in a way. Rice is an agricultural product, and as such will differ from harvest to harvest as to how fast it will absorb water. But I performed this experiment anyway: I made two batches of koji in a row. For the first batch, I soaked the rice overnight as I usually do. For the second batch, I put the rice in a graduated container and soaked it until the original volume of the rice increased by 33% - this only took a couple of hours. The results were pretty similar, except that the rice that soaked overnight was stickier (tenaciously so, it stuck to my hands quite badly) than the rice that only soaked for a couple hours.
So, now I only soak my rice for a couple of hours whether I'm making koji or a full batch of sake, but I always watch for that increase in volume. If you're soaking 3 cups of rice, you'll know it's ready to steam when you have 4 cups of rice in whatever container you're using to soak it.
01/29/09 @ 14:04
Comment from: tony [Visitor]
thank you bob. I've been making sake for over 4 years. this has been very informative. I have been researching ways to improve my skills. again, thank you. i am going to make my next batch this week. wish me luck
tony
02/21/09 @ 21:26
Wow, four years and you're still finding ways to improve? That's great! I'm glad I could be of help, and I wish you the best of luck in all of your future batches of sake.
02/22/09 @ 22:58
Comment from: Geoff Steckel [Visitor]
Thanks for your very informative text & pictures! They've been very helpful.One question that's eluded me: where to get bags for straining the delicious result? I wound up using a lab centrifuge which let me spin down 3 liters at a time - not bad, but not authentic either. I'm currently culturing about 9 pounds of koji for a 5 (or so) gallon batch of sake and would like to be able to filter it correctly.
Thanks!
03/03/09 @ 08:30
I'm glad you found this guide to be so helpful, Geoff!To separate my sake from its kasu I use a small stainless steel fruit press and inexpensive 5-gallon capacity nylon paint straining bags that I pick up at my local Lowe's hardware store. Not traditional, either, but to date I have yet been unable to find a source for the burlap or canvas bags that are used by sake kura.
I suppose some day I may talk my wife into making some for me. =) Until then, the paint straining bags suffice.
03/03/09 @ 10:40
Comment from: Chuck Blanchard [Visitor]
Hi Bob,I was checking out the Gem Cultures website and noticed that they had 5 different strains of Koji-ken with one of them listed for sake and the rest for soy sauce and various misos. I didn't realize there were different cultures of Koji-ken until then. Have you tried the Gem Cultures sake spores (which are cheap if you buy the larger quantity) and if so, are they the same strain as the Vision Brewing spores.
I also just made a batch of sporulating Koji for my next batch and I was wondering about long-term ability to grow a mono-culture. It seems like over time the chance of something else building up in the spores that you are using would increase. Obviously just buying new spores from time to time would be a cheap solution.
Thanks,
Chuck
04/15/09 @ 21:21
I'm afraid I don't have definite answers for you either way, Chuck. I haven't tried the spores from Gem Cultures, mostly because I prefer to buy things locally when I can to support the small businesses around here. The spores used in my guide were the Vision Brewing ones, purchased from my local homebrew supply shop. What's the difference between those and the Gem Cultures spores? I haven't the slightest idea, sorry.
As for the viability of maintaining a long-term pure monoculture, I don't have any definite answers for that either as I just started growing my own koji last year. I am, however, operating on the working hypothesis that as long as your koji making method is sound and sanitary, you should be able to maintain a monoculture indefinitely. I have two pieces of evidence to back this up.
First is the way the mold itself works: koji produces filaments that coat and penetrate the rice grains just about completely, and is very active about doing so provided you've set up the right kind of environment for it. It's also snow white, so it's pretty darn easy to identify when you have something funky and non-koji growing in there. It's not like yeast where you have a bunch of free-floating microscopic critters in an aqueous solution, and so the only way to get a pure monoculture is to start with a single isolated cell and culture up from there in a rigorously sterile environment.
Second is tradition: the method I describe for propagating spores is pretty much exactly the same method the Japanese brewers have been using for hundreds of years with a great deal of success.
Now you know as much as I do. Good luck on discovering your own answers!
04/15/09 @ 21:42
Comment from: Chuck Blanchard [Visitor]
Hi Bob,Is any biological activity expected prior to pitching the yeast. 24 hours into letting the rice and koji mixture sit as part of making the moto, there is definitely a little bubbling going on. I think it may be a wild yeast, but I'm not sure.
04/18/09 @ 10:03
Hi Chuck! Wild yeast and lactobacillus activity are to be expected unless you're using the shubo technique (adding lactic acid, which I don't do).
04/18/09 @ 10:07
Comment from: Jeff [Visitor]
Hi Bob, Do you have a ratio of clear sake/leftover solids to make nigori? Thanks!
05/15/09 @ 20:57
I sure don't. When I make nigorizake, I just bottle it directly from pressing. It's a little thick that way, but nobody ever complains. =)
05/15/09 @ 21:06
Comment from: Jeff [Visitor]
oh.. Yea, makes sense that way. I tried a half and half mix... whoo boy.. there's a kick...
05/15/09 @ 21:23
Comment from: Joe [Visitor]
Hi Bob,I had experimented on a pan of Koji and "held back" causing dehydration where the rice then became tane-koji overnight. Being that now I have a pan of it...I can storage it. Assuming I cannot use it at this growth stage for adding to make sake as an alternative to the 'white?" Storage temps? Thanks very informative!
08/17/09 @ 00:12
You're right in koji that has gone to spore not being suitable for adding to sake - at that stage of its growth cycle, the fungus has started to produce kojic acid and other toxins that you wouldn't want present in something you intend to drink.As for storage, I just keep my tane-koji in a shaker in the cupboard above my stove. Once dry, the rice and spores aren't particularly temperature sensitive. When I want to make a batch of koji, I just take the shaker down, remove the dust cap, and shake the spores on.
08/17/09 @ 02:30
I've just had some good results using a heated propogator to grow the koji - just a cheap little one - no temperature control - and it worked great.Possibly a little too well, because having been very pleased with myself this morning seeing beautiful, white furry rice, I just went to box it up to discover it's all got a decidedly green tinge already and I'm going to have to start over.....
09/10/09 @ 04:25
Comment from: vince [Visitor]
how much Kome-Koji do you have to use to make enough spores for the next batch? And when you refrigerate kome-koji does that kill the mold or can you revive it by re-hydrating and warming it up. Just curious if some cold mt koji can be used to make spores
10/08/09 @ 20:48
Hey Vince! Sorry for the delayed response, for some reason I didn't get an e-mail from my back-end software about your comment. Not sure what's going on there. Better late than never, I guess. =)I reserved only 3/4 cup of kome-koji to turn into tane-koji - the very same 3/4 cup illustrated in this guide, by the way - and have since used it to inoculate 4 more batches. In fact, I won't say it's time to make more seed koji until it seems to be getting difficult to get spores out of that shaker. How many batches will that be? I have no idea. But 3/4 cup (more like 1/3 cup now that it's completely dried out) has been more than enough to make more koji with.
Refrigerating or freezing koji doesn't seem to hurt the mold much, if at all. I've had reports from people who have made tane-koji from their own frozen koji as well as from people who have done the very same with Cold Mountain Koji.
11/18/09 @ 15:54
Comment from: Peter [Visitor]
Bob,I came across this site long ago, well before the radio show brought up popularity and interest. I had a hard time sourcing koji-kin spores to start with so I lost interest and got heavily involved in beers and meads which are more easily sourced ingredient wise.
Now I got my rare and only pack of Koji-kin. My goal is not to make any Sake with it. I only want to make Koji and only tane-koji. So I want to take rice to growing koji to sporulating and then storing up a massive batch of spore laden rice to hand around to other brewers at the local brew club.
If I can do this then and only then I'll start working on actually making Sake from the next batch made from my own tane-koji.
That said, if the only goal is to make tane-koji can I just dispense with the whole expensive polished rice as I'm not seeking flavour attributes, just a cheap base to make nothing but tane-koji. Does short grain rice even matter or can one just use the cheapest available or even long grain and leave the short grain and highly polished rice for when actually making sake to drink?
Pete
12/18/09 @ 18:50
Hello, Peter! I'm sorry to hear that koji-kin is so difficult for you to source wherever you live. To answer your question:The type of rice you use to make tane-koji really doesn't matter. Indeed, the tradition is to use brown rice for that purpose. Why? I really don't know. I use plain old short grain sushi rice to make all of my koji (in fact, I use that rice for just about all of my sake, too) and have never had any ill affects from doing so.
Long grain rice? I honestly don't see why you couldn't use it. It's not traditional, but I can't see why it wouldn't work just to produce some tane-koji.
12/18/09 @ 22:10
Comment from: samuel sapp [Visitor]
Kome-koji how much you have to use to make sufficient spores for the next batch? When cool kome-koji does that kill the mold or can be revived by re-hydrate and heating. Just curious, if a cold mt koji can be used to make the spores
01/10/10 @ 22:25
Comment from: JJ [Visitor]
According to Vision's website: http://www.tibbs-vision.com/maltrice/index.html A 10 gram packet will produce approximately 6 kilos of Malt Rice (rice that has been enriched with enzymes from the growth of Koji mold. I am intending to steam 6 kilos of kokuho rose and inoculate it with the 10 grams of spores. Do you think this will work? I ask because they only provide the 1.5 gram to 400 gram recipe and I can't figure out how to multiply that up to 6 kilos. Thanks for the wonderful website.
02/06/10 @ 18:59
In all honesty, I've never been able to get Vision Brewing's math to add up either. That was my primary reason for discarding their instructions entirely and writing my own.The biggest problem you are likely to run into is incomplete coverage of the rice by the mold, which stems from using a sifter or other means to distribute a pre-measured amount of concentrated spores (or spores blended with flour) over a given amount rice. My experience since writing that guide has taught me that I get much better coverage by making my own tane-koji using the vision spores, then using the tane-koji inside a metal salt shaker to distribute spores over my steamed rice. No measuring of spores is required, just shake and mix and repeat until the rice takes on a noticeable green tinge from the spores.
02/06/10 @ 19:40
For anyone who might happen to be watching these comments in the feed:I've done a significant update to this guide. Two very important bits of information have been incorporated:
(1) The impact of incubation temperature on the final enzymatic properties of the koji, including updated incubation temperature ranges. In essence, koji likes to produce mostly protease in the lower portion of its preferred temperature range and mostly alpha amylase in the upper portion. This changes the target incubation temperature recommended in this guide from 85ºF to 96ºF.
(2) This hasn't happened to me, but it's worth pointing out that flour is a possible source of contaminants in your batch of kome-koji. In this guide I try to get around this in two ways: by using bleached flour, and by making sure that the amount of spores I'm using is triple the amount of flour that's being used to cut them. Still, I've added a note about the possible contamination issue, pointing out that the only way to eliminate it altogether would be to omit the flour.
I've also gone back through and tried to make the inclusion of Celcius temperature conversions more consistent.
Anyway, it's worth going back through and re-reading the guide to see the changes I've made. Hopefully it'll help you guys make better koji in the future.
02/16/10 @ 00:13
Comment from: Little Grasshopper [Visitor]
Re: Tane Koji...I am making koji with the hopes of making both tane-koji and koji.
Am I to understand that whole rice (not polished, i.e. with husks) are best for making koji and tane-koji?
I was thinking that my whole grain bhutanese short grain rice seems to have a nice structure (solid, etc) and might make for good koji - or am I mistaken? Have you tried brown rice?
I've made koji from Vision spores before, I'll keep you updated. Still no source of red-koji, I have been trying to look for a lab, but no luck yet.
02/16/10 @ 13:19
Comment from: Little Grasshopper [Visitor]
Bob - The tane-koji I made I stored in a mason jar with a perferated screen on top. It started to mat together, like fibers. A bit like koji, in fact. Most of it is still green, though, and I'm just curious - does this seem right? I am considering taking a half cup of my frozen koji back to warmpth to create more spores, rather than risk this whole thing, whaddyathink?
03/11/10 @ 20:58
Sounds to me like things might have gotten a bit humid in your tane-koji storage solution, so some of your spores may be sprouting. That's just a guess, though, I can't say for sure.If in doubt, throw it out. =( It's better to have to start over than risk making yourself or someone else sick.
03/12/10 @ 13:02
Comment from: Little Grasshopper [Visitor]
Thanks always, Bob. I've got out and warmed a half cup of my own koji I had frozen, and now it's just turning green. I'm wondering if I just had a bit too much tani-koji in the jar, and the humidity just couldn't escape. It's been unusually humid here (desert) this year so maybe it's dryer during the winter in Ak with the heat on? Not sure...Anyway, thanks again.
03/12/10 @ 13:07
Comment from: Marcus M [Visitor]
A query for you, if i may: Apart from the spore colour and smell, is there any way of positively identifying a potential koji culture as such? i ask because I have followed the instructions in Bill Mollison's "Permaculture Book of Ferment and Human Nutrition" for capturing a wild strain of Koji by hanging balls of steamed rice in bamboo-leaf slings under the eaves of a house and allowing spores and mycelia to grow on them. Of the two that i have tested so far (two of bamboo leaves, a further two wrapped in banana leaves that i haven't opened yet), one was covered in black spores, the other had a mixture of black and a good patch of green. I made a culture of both colours in seperate sealed containers of steamed rice and the green one seems to be pretty viable and closer to the 'ideal' (the spores it's producing are about the right colour, the mycelia tried to form a clump, etc.), but as it's a wild strain, i'm a little hesitant to use it in a brewing.
Short of sending a sample to the CSIRO for analysis, how can i get a positive ID for this?
Thank you kindly.
03/29/10 @ 21:43
Comment from: Don Veasey [Visitor]
Thanks for the guide! I started my first attempt to make Koji-kin today. The cold
mountain brand is just not in Florida. Wish
me luck.
04/08/10 @ 09:41
Comment from: gbsk [Visitor]
Bob,I live in Wasilla. I was wondering if I could see your operation and talk to you about making koji and/or malt rice. I will be coming to Anchorage on Sat. if that would work. This is a great site with lots of info although I am still a little confused.
Thanks
04/09/10 @ 00:43
Comment from: James Blond [Visitor]
Hey!So this time, to avoid rotten rice-tane-koji, I just froze the shaker that had the tane-koji, until I was ready to use it. Worked like a charm!
Natch~!
04/30/10 @ 08:21
Comment from: Alejandro [Visitor]
Hi BobThis is my problem. i only have Aspergillus oryzae cultived like colonies on a inclined essay tube in the laboratory and in my country (Chile) don't sell the koji's spores. i put some colonies on a broth of malt extract to activate and proliferate the Aspegillus, and then i spray this broth on the rice to inoculate, simulating the addition of koji's spores that you do in your guide. At 24 hour later, the 50% rice grains begin to color itself with a green-mint color (inside the grain, not outside) and at 48 hours is almost all of that color. Along this 2 days, the rice smells like nuts with a sweet touch. this is alright? What you recommend to do?
exist some way to send you a photo of this?
05/27/10 @ 18:47
Comment from: Derick Jones [Visitor]
I will be trying to make Koji for the first time this weekend. I am so glad that I got to read about these tips and also look at the images. At least I can gauge if I am on the right track. Super cool! Thanks.
06/29/10 @ 21:20
Comment from: Kim [Visitor]
Mr. Taylor.I found your webpage 6 weeks ago when I was on my search for koji making to make miso. Your site is the only one that is most impressive, and the only one shows how to reproduced the Koji spores. A few months ago I started to make tempeh and learned how to reproduce the spores, and your technique is so similar. I have been successfully making many batches of Koji rice and wheat since. I like to share my experience with your reader, especially those who has not have much success in making koji. The first batch I made with long grain white rice, it came out good, but I was not too impressed. The next batch I used organic short grain brown rice, it came out perfect, but when I put some on a plastice container to let the spores mature, it did not turn out as green as I hope, but I was able to use it for my next batch. I cooled the rest of the koji rice and left refridged in plastic bag, a week later I took it out to use, to my surprise, lots of the grains look light green. I Picked out those grains and let it dry, and used in my next batch. Since then I have made many more batches of Koji seeds. My routine is to washed soaked brown rice or wheat for 4-6 hrs, drain 1-2 hrs, steam in cheese cloth 1 hr, take the rice out of the steamer in the cloth and placed in a baking pan, let it cool down then springkled spores on it and mix it a few time, then twisted the cloth to make it into a ball, sprayed with filtered water, and placed into a large salad bowl. I mixed it up every 12 hrs, and moisted with spraying water each time( I also used 2 in/out temperature gages, it's a must). I spread it out on a baking tray when it getting too hot(104 or higher), also turn the lamp off at this time, but kept the cloth on until I see some greens. I used the oven and an adjustable lamp, I also placed a large bowl of water on the bottom of the oven. This weekend I made koji with the malted wheat I got at the brewery, and it turns out to be the best so far. I's very sweet, and already has green dust by 36 hrs. I let it dry in my cupboard until I get back from my work next week, then I'll mix it with some lightly roasted rice powder, and grind it into powder in the coffee grinder ( this is the technique I used for my Tempeh spores.)
Just want to let you know how much I appreciated your works and your webpage. And if has not been for you, I wouldn't have a life time supply of koji spores:).
07/05/10 @ 11:36
Comment from: Russell Taylor [Visitor]
Hi Bob,just thought id mention your warning on mixing koji with flour with contaminants. I read you can heat the flour on a skillet for a couple of minutes before adding spores to make it sterile.
08/18/10 @ 03:02
Comment from: Daniel Levy [Visitor]
I've followed this guide twice on making koji , and I think it's pretty good, but I have to say that the temperature spike as the koji reaches it's final steps is *really* annoying as is the need to break up and cool it. But I've never seemed to be sure if I let the koji grow for enough time before freezing it. ( as I'm I'm fairly sure I'm close to the correct end product, somewhere between the second and third pictures/ tan vs white..). But I'm rambling.. my main question is that if you are unsure how thoroughly complete the koji is, how good an idea is it to add some extra koji to compensate for potentially less enzymes.
12/18/10 @ 03:44
That is entirely a judgment call on the part of the brewer, Levy, and not really something I can give good advice on. If it were me, I would just follow the recipe and observe the results for myself. If I had some question of the potency of my koji, I would first make some amazake with it. If it doesn't reduce three times its volume in rice to complete mush in 30 minutes at 155ºF, then I would start to question its potency and maybe make adjustments to the amount I add to the sake.More likely, however, I would just start a new batch of koji and hope I do a better job the next time around. =)
12/18/10 @ 12:52
Comment from: lars [Visitor]
I was wondering if you had a gram/micro scale. Just so I can pin down what the 1.5 teaspoons of aspergillus amounts to exactly.Thanks a lot for the great site.
01/13/11 @ 09:24
I don't have a gram/micro scale, lars, sorry. I can tell you, however, that 1.5 teaspoons is 7 milliliters.
01/13/11 @ 11:06
Comment from: john [Visitor]
What do you think of this method of making koji? Scroll down a bit to get to the "Old fashioned koji" parthttp://www.permacultureproduce.com.au/how-to/56-make-your-own-miso
03/29/11 @ 12:06
I think it's a good way to make somebody sick. While there are usable varieties of koji that are black or grey, but allowing them to get that far in their life cycle means that they will have begun producing kojic acid. Which is toxic. Other than that, there is also significant risk of growing other, more toxic varieties of mold instead of the koji you're aiming for. Remember, aspergillus is everywhere, but the specific varieties used for making miso and sake were native to Japan. The likelihood that you'll find those varieties floating around in your back yard is pretty low, and almost every other variety is highly toxic.
I would only recommend making koji from known spores obtained from a reputable source.
03/29/11 @ 12:41
Comment from: Steve Covey [Visitor]
Bob thanks for this great informative site for making Sake. I've completed making the Koji and almost finished making the koji-kin spores. Sake is next, but I do have a question. Following all your instructions I could not predict that my wife would insist that we need to go into town. I was on the 44th hour making Koji, of the 48 to 50 hours you recommend. Problem was the Koji was making its own heat and getting over 100 deg in a hurry. I was taking it out to cool often and it was keeping me real busy. The wife said "let’s go", so I made a command decision to remove the Koji and placed it as is in the refrigerator, short of 1/2 cup of Koji that I left without water in the incubator. I knew that I could not leave the Koji to overheat and I could not stay. I know that I'm about 4 to 8 hours short of some critical time making the Koji, by your example anyway. My question is; can I take the Cold Koji and put it back into the incubator, add water and finish the Koji process? Or do I just go with what I got and hope for the best in making the Sake? I will start the Sake process next week. I would like to get your expert opinion. The koji-kin spores seem to be drying well and should be ready for the next batch. I hated to leave at such an active part of the process, but you got to do what you got to do sometimes. I also don’t want to ruin the Koji by placing it in the incubator if will harm it in anyway. You may not have ever been in this situation before, so your best guess answer will work. Thanks again,
Steve
04/25/11 @ 12:04
Hey Steve, thanks for the wall-o-text! I totally understand about life (or wife, hah!) taking you away from your ongoing project before it's quite ready to rest. Happens to every guy at some time or another, I think. =)Fortunately, koji is pretty forgiving stuff in terms of incubation time. The important question is not "how long did it incubate?" but "how much coverage and how deep penetration did the mold achieve?" If the koji has covered most of the rice with mycelium and managed to work its way most of the way into the kernel (cut a piece in half lengthwise and inspect with a magnifying glass), then you're good to go.
If not, well, warming the koji back up and keeping it there should kickstart its metabolism again. Don't supply it with any more water, though. You want the mold to have to reach deeper into the rice to get the water it needs, which will in turn force it to produce more amylase.
04/25/11 @ 19:13
Comment from: KevinMH [Visitor]
After overshooting a batch of koji (First one failed, second one overshot the mark.) I've been letting it try to dry and spore.I notice that it's mentioned to put the sporing koji into a container and you leave it there to finish drying out. How long does it take to completely dry?
I've had mine in containers with opened lids for a few days, and I continue to see condensation in the container (Sides and bottom) as well as exothermic activity.
I'm loathe to shake it around to redistribute the heat and moisture, since it would mean spore loss, but at the same time, I don't want the spores to attempt to sprout and create another mat which it seems to be trying to do.
Does this happen to you (or anyone else)and any ideas on what to do to end the moisture and heat that's being generated from the sporing koji. Or do you just let it run even this full course, even with water visible on the inside of the container?
06/26/11 @ 22:47
Comment from: Bonsaier [Visitor]
Hi, I've been making very good sake for about 3 years and have come into posession of about 30 pounds of black rice. Have you ever made or heard of anyone who has attempted to make sake from the "forbidden" rice?
07/10/11 @ 20:30
Comment from: Chris P [Visitor]
Hi Bob! Let me first start out by thanking you for what is probably the best how-to manual I've ever read on the net.I've been having some trouble making koji though, and I was hoping you could give me some advice. I'll describe what seems to be happening and you can let me know what you think is wrong.
I finally had a good batch of steamed rice this past week, after learning how to use my new chinese steamer. So, I think I'm starting out with decent rice: it's gummy, pretty hard and not sticky to the touch (though I have to break apart clumps after the steaming is done).
I sprinkle the 1.5 teaspoons of koji-kin and .5 teaspoons of white flour (mixed) over the rice after it cools. Although, my sprinkler was a little damp, so I lost around a third of a teaspoon of spores. But I figured the mold would spread, right? (maybe this was the problem? let's see)
I made the same incubator as you have -- cooler, two hot blankets, tupperware 1 gallon container, cup with water for humidity. Everything is going well up until the 40 hour mark. My koji looks like yours does at the 40 hour mark.
But then things go downhill. At some point between 40 and 45 hours, the rice starts to turn a mint-green color, from the inside. The koji is still white and I can see strands of it, but it seemed to have stopped spreading. Instead, the rice is turning a little green. It's weird.
So, I never reach your final mat-of-koji stage in your final picture, instead I get a box of slightly green rice with a moderate amount of white koji spores. (about the amount shown in your 40-hour mark picture).
Again, the koji is white, but the rice is kind of green.
Could it be because there's too much humidity? When I open the cooler there is a lot of water condensation on the lid, so much that it runs down the side when I open the lid. Maybe the rice is rotting somehow?
Just for interest's sake I tried to make koji-spores with a 1/4 cup of this koji, but at the 30-hour mark the rice itself is very green, the koji itself is still mostly white. So weird.
Any help would be appreciated! Again, thank you for such a wonderful site.
09/02/11 @ 08:12
Comment from: Chris P [Visitor]
Sorry, another question -- does koji mold need darkness to grow?Because I'd rather use a lightbulb as heat. The heating blankets take a very long time to heat the cooler, I'm finding.
But I'm worried the light would maybe change the enzymes in some way that's difficult for me to detect (until the sake is made).
Thanks again!
09/02/11 @ 08:50
Thank you for the compliment!It's kind of hard to determine exactly what your problem is without seeing some pictures, but if I had to take a guess I'd say that what's happening is either your koji is going to spore on you or inadequate spore coverage and low sanitation resulted in some other strain of mold getting in there and competing with the koji. Either way, throw the batch out and start over.
On your next attempt, try this:
First, any flour you mix with your koji spores should heated (in a hot pan) to sanitize it, especially if you're like me and primarily keep unbleached all-purpose flour in the house. That will help keep your competing mold spores to a minimum.
For the first 20 hours incubate your koji at 92ºF with the water in place to provide high humidity. Then remove the water (to lower the humidity) and boost the temperature to 99ºF for the remaining 20 hours of incubation. When I switched to this more advanced bi-level technique, the results were faster mold growth, better penetration, and better coverage.
I don't think koji is affected by light, so you should be fine using an incandescent bulb for heat. =)
09/02/11 @ 08:54
Comment from: Chris P [Visitor]
Wow, thanks for the quick reply!As for the green rice, I really don't think it's a competing mold. There is no other mold-like growth on the rice, the rice just all of sudden has a greenish tint, from the inside. It's happened to both my batches so far, both times around the 40-45 hour mark.
But, I will try this again and use your bi-level technique and report back. And next time with pictures. :)
Using the light-bulb: I wonder if maybe I should cover the plastic bowl with a black cloth to shut out the light, just in case it affects the enzyme production? (I'm not paranoid... not at all...)
Thanks.
09/02/11 @ 09:33
Which is why I said it's hard for me to say exactly what might be wrong without seeing a picture or handling the rice in person. Here's something you might consider, however: steamed rice naturally has a yellow tint to it. This yellow tint could be perceived as green under certain lighting conditions. Anything that changes the way light refracts through the translucent rice grain or reflects off its surface would also have an effect on the perceived color.As for using the black cloth to protect your koji from light: it certainly couldn't hurt anything. Nothing wrong with a little paranoia. =)
Harkening back to one of your previous e-mails:
Koji does like to spread its mycelium around, but it's been my experience that it will only do so to a certain extent. If you don't get good coverage of your rice with mold spores to begin with, then you'll only have partial coverage of your rice grains with fuzzy white mold in the end.
But you know what? That's okay. The resulting koji can still be used to make sake or produce tane-koji. =)
09/02/11 @ 14:34
Geez Bob, just ordered 50 bucks worth of vision spores and threw out a tray of green koji, being VERY careful not to inhale any poisons. I really should slow down and read a bit more...and drink a bit less
09/11/11 @ 22:03
Koji isn't poisonous, man. It's not known for causing aspergillosis, either. Japanese sake brewers have been breathing those spores in for hundreds of years with no reported ill effects. I just put the warnings against inhaling the spores in my guide because it never hurts to be careful.
09/11/11 @ 22:08
Comment from: Rick [Visitor]
GREAT site, a million thanks! A quick question. During the fermenting of Koji, what humidity range do you think is needed? Like a RH of 50% or so? Then drop to 40% or so during making spores?
09/15/11 @ 04:46
Comment from: svetaxp [Visitor]
Great article! Maybe you know how to koji-fy more rice with ready rice koji? I just got a rice koji package from Japan, I'm planning to make amazake. I really need the package to last forever:), I've heard it's possibe to make more rice koji seeds with the koji you have, but I can't find how to do it. Amazake is great for milk production and my friend is going to have her first baby in a month.
10/22/11 @ 12:17
This forum thread on the topic of producing tane-koji from prepared koji is very likely what you are looking for, svetaxp:http://forum.northernbrewer.com/viewtopic.php?f=21&t=101189
10/22/11 @ 16:59
Comment from: Adam Kiryl [Visitor]
Thanks for the advice on making koji rice.I would like to make a test portion for making miso. I have been making natto for a while, in small batches and so far they have came out really well.
I have a small toshiba yogurth maker and I intend to use it to try making a batch. It can be setup to keep the temperature at a given level. If I take care of the humidity I think it will be fine.
11/07/11 @ 07:23
Comment from: Don Veasey [Visitor]
I'm using my third generation of Koji-Kin from this method. Works perfect.
12/12/11 @ 17:00
Comment from: RTM [Visitor]
I made koji rice and miso about eight years ago, using several varieties of rice, and several kinds of beans as well as artichoke hearts. All of my four batches came out great, but in reading this blog, I see references to keeping the humidity at a certain point. I didn't do that back then, and am about to make miso again. Is it important to keep the humidity to a particular level during the 46-48 hours that the koji is growing?
01/23/12 @ 16:40
Comment from: Juan [Visitor]
Hello, your work is great!I live in Argentina and koji spores are unavailable and cannot be mailed here. But I have some dried koji-rice left.
Is it possible to innoculate a new batch of rice using this rice-koji?
Thanks,
Juan
01/30/12 @ 04:43
Comment from: Kirsty [Visitor]
Okay, so I have attempted to grow spores like this however I ran into a slight problem. It seams the australian climate may be too humid or I'm having some control issue.While I was able to get the koji to take on that greenish colour and grow and look like yours it was not sporing, only in advanced levels of growth and died soon after. I got no spores from the koji.
Not totally sure what I did wrong.
Could it be something to do with the rice being too soft (I have been using a rice cooker to steam my rice)
03/06/12 @ 22:27
Comment from: Kirsty [Visitor]
Le sigh. So - I got a batch to spore and found a container almost like yours. I tried to innoculate a large batch of rice so I could take it and store it and not have to make some for a while.But alas I screwed up. Right up until the 30 hour mark in the evening everything was on track and it was the right colour, texture, smell everything was working... But somehow when I checked it at that point I must have contaminated it as the next morning I had this pinkish coloured mold growing in veins through my rice.
Had to throw the batch out.
The moral to this story - when you go to check on your rice and stirr it make sure you sluce down your equipment and hands to make sure there isn't any bacteria on them!
[Rolls eyes] Gotta start again!
04/01/12 @ 03:58
Comment from: Peter [Visitor]
OK, so I guess the kome koji will not turn green when I start making the sake in my primary fermenter? I am also worried if it can be too humid in my incubator, and if so what does that look like.I happened to have a chicken egg incubator lying around that my sisters had, and it works perfectly. I laid the thermometer on top of the batch and it fluctuated between 90 in the beginning and 96 as the koji started growing.
06/10/12 @ 17:56
Comment from: David [Visitor]
Hi Bob;I finally got around to making a koji grow box, with temp control, and followed your recipe using the "V Brewing" spores. Everything was going fine, but I came home today to see the koji has all turned that now famous 'light mint green' color, with only a scattering of fuzzy white grains. I'm confident there is no contamination just over ripe koji. I tasted several grains and they have a nutty, cheese like flavor with a very noticable sweet taste. I'm thinking this will act as the 'white' koji would but might have a stronger flavor addition to the finished product??? I know if I let this finish drying I could use this as the tane-koji for more seed spores, but could it be used for making a batch of sake? Just wondering... I'll start over and use this HUGE supply of spore stock to seed it if you think that's best. And THANKS for all the great info... I'd have NEVER tried this without the info you have here.
David
03/25/13 @ 15:12
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