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Koji fail

I just went through a full packet of Vision Brewing Koji-kin and have two gallon-sized rubbermaid takealongs full of yellowish moldy rice to show for it. It’s moldy but it’s not white. What am I doing wrong? I followed the Taylor-MadeAK instructions very carefully. It seems to start OK but then slowly turns yellow. I have made several hundred batches of beer and a few meads but I can’t even get thru step 1 of sake.

More details about your equipment and process would be helpful. Not that you followed my guide, mind you, but what you actually did. You kept notes, right?

Thanks for responding.

I thoroughly washed 2 pounds Kokumo Rose Sushi Rice and then soaked for 1 hour and 15 minutes (1.5 hours on second batch, final weight of second batch after soaking was 2.6 pounds) and then steamed in a cheesecloth-lined bamboo steamer for 45 minutes (1 hour on second batch). Dumped it onto an aluminum half-sheet pan and broke it up with my hands (I wore latex gloves at every step to try and be sanitary). Then I mixed 1.5 tsp koji-kin with .5 tsp bleached white flour that had been heated in the oven to sanitize (I only heated the flour, not the koji-kin). I evenly distributed the koji-kin mixture in 3 batches using a small tea strainer, mixing it in each batch. Then it all went into a 1 gallon rubbermaid takealong and then into a Coleman cooler with a heating pad, heating pad had a small glass of water on top. I used a digital meat thermometer to monitor temp. Everything was sanitized prior to use. Temp was mostly kept between 90 F and 97 F but both batches reached 100 F at the peak of generating their own heat (at which point the heating pad was completely off). I only opened the cooler to stir which was done every 10 hours. On the second batch, I would dump a little boiling water from a teakettle into the bottom of the cooler to try and quickly replace the moisture that had escaped from opening the cooler. There was condensation on the walls and inner lid surface of the cooler for both batches. I also placed a single layer of cheesecloth on top of the rice for the second batch

I think it was your site that said that it was maturity and dehydration that caused sporing so I was trying to prevent dehydration on the second batch, hence the slightly longer soak and steam…and dumping the boiling water in the cooler…and the cheesecloth. But both batches went almost identically; white mold at first (noticeable at the 20 hour stir) that just turned more and more yellow as it went along. Each batch was generating enough heat to turn off the heating pad between the 20 and 30 hour stir.

I probably forgot something but I think that’s about it. Oh yea, it tasted nutty/slightly sweet and fuzzy; but it’s not white.

Here’s a pic but the slightly reddish area in the center is not really red, just a bad photo. It looks more yellow than the pic:

EDIT: Here’s a better pic with an egg placed on top of plastic wrap to illustrate how not-white the ‘koji’ is. You can also see a few broken pieces showing the mycelia penetration.

For me, Vision spores makes koji consistantly more yellow-white than white. Akita Konno Special Ginjo Koji makes white koji, same process in both.

Vision I suspect is a soybean koji, not a true sake koji. The higher temps just make Vision mature faster. In order to get the high amalayse levels, using vision requires some pretty good treatment and steaming of the rice. Because the koji seems to mature faster, too much moisture causes the koji not to go deep and seems to want to spore sooner.

When I bust up the koji matting, it turns more yellow like that. I’ve made 8 batches of vision, all turn out more yellow-white than white.

I agree with dray, that looks like a pretty normal batch of koji from vision spores to me, and I can’t find anything off with your process. I would go ahead and use it to make some sake.

OK, thanks guys! Hopefully all goes well from this point.


Hi all. In lieu of started a new thread, it seemed a good call to revive this one with a variation.

Basically I am wondering if I have koji that has gone to spore, about to go to spore or ‘normal’ koji from Vision spores.

In theory I have followed the Taylor-Made guide. That’s what I suspect they all say, so here’s the notes - assume proper sanitation. :

  1. Soaked 8 cups Kohuho Rose (3.66 lbs) in water (after rinsing) for 1 hour. Drained 1/2 hour. Soaked weight 5 lbs.

  2. Steamed 45 minutes

  3. Cooled to 95 F

  4. Into the cooler, with heating pad on bottom, with bowl of warm water on top, and bin of rice suspended above.

10 hours - stirred. Temperature remained 95-97 F (using controller specified), probe in rice). No sign of growth and specifically no aroma of sulfur or anything else.

20 hours - stirred. ‘Spots’ rice…although not a perfect white. 94-97
26 hours - stirred. No real change. Made a decision based on lack of aroma and less moisture than I believe should have been there to boil some water, cool it, and spritz down the rice while stirring.
36 hours - Activity! Temperature up 101 F. More tan-yellowish coverage.
38 hours - this was 11 pm and just happened to get up and decided to check in - DAMN!! 107 F. I ‘fought’ for the next 2 hours to get and keep in down under 100F, stirring and cooling every time it got above 100 F. Nearly every 15 minutes. Continued to mist with coolish water. The rice was never wet. Went to bed
44 hours - Very full coverage. rather tan koji, with hints of oche yellow. My eyesight (not bad, but '40’s annoying) and a lack of magnifying glass kept me from seeing penetration. Temperature hovering in the 98 F range, with more cooling every couple hours now. Tasting sweet, nutty and smelling finally.
50 hours - coverage continues and color deepens. No longer going exothermic. Holding nicely 96-97.
56 hours - Of course, now starting to wonder if it went to spore. Does not seem green enough, but uncertainty has taken hold. Nice nutty aroma. Good sweet flavor. Decided to pull all but 1 cup.

Below is a few photos. The 1 cup is still in the incubator, water removed, holding at 96 F.

[attachment=2]koji 2 small 2.jpg[/attachment]
[attachment=1]koji grains.jpg[/attachment]

So, does anyone have and opinion if I have classic Vision koji or spored koji? And if I can use it for sake.

Thanks for any input. Right now the bag of koji is in the refrigerator. Sake brewing in a week or so, assuming I don’t need to make more koji.

I’d say that is about as mature as you would want to go. Maybe there was extra condensation?

Looks like beginning stages of fruiting to me. Personally if the color of the photo is correct, a little green for me, but its right on that line in my opinion. Getting closer!

From what I’ve seen in my Cold Mountain Koji growth, these photos and the yellowish descriptions, I’d have to guess that CMK uses Vision Spores…or at least the same species after all.

Thanks for the reply. I am going to move forward and see what I get. I left about 1/2 lb in the incubator and it is now very green, 3 days later. Very clearly in spore.

Dray, the humidity was quite high. I had moisture on the was of the incubator, but due to my arrangement, not on the walls of the container where the koji was. Why do you mention that maybe there was extra condensation? I know there is a variation of the koji growing procedure that has you reduce the humidity after the first 24 hour or so. Is to that what you refer?


When I have too much moisture, I get that mottled look. If there is too much condensing moisture, I believe the koji won’t penetrate into the rice as deep and will mature faster and start sporing. The off-color matting is the precursors to spore structures, I think. When I see koji like this then in as little as 8-10 hours later it turns green, no longer any doubt.

The flip side to this is: I get a bunch of dried out rice grains with no growth…

For me its either dried out rice grains or near over mature…

Thanks Dray. I think that helps. It’s funny. I found it too dry (because it was not progressing) but then it seems too damp. I think I may have over drained in fear of being too wet in the beginning.

I’m just about to start my Moto tonight with this Koji…with, as I’ve decided, my ‘constant proportions and exact doubling’ (see the next thread down about ratios) and see what I get. Horrid scientific method I know, changing more than one variable, but it is as it is.

I made a google spread sheet after I saw your post.
Dray’s Google Sheet Sake Calculator

When I plug in the values in Taylor-MadeAK’s guide, they are very close (cups to lbs is not precise) and could be used to determine the additions.

Hope this helps,


I just wanted to report in.

I’ve used the above koji in my current batch. I had an unpleasant shock that the resulting liquid turned a greenish color. :shock: But it went away after about 18 hours. I think there could well have been a touch of spore, but I’m thinking it was broken down just fine. Due to a calculation error, I had to make a 2nd addition to my Moto, and gave the koji a very fast water dunk and rinse. A bit of green was left behind and my Moto did not turn any odd colors. I plan on doing this same rinse for each addition. It certainly didn’t hurt the enzyme activity as evident from the wonderful conversion/breakdown I am getting. Better than CM IMO.

Yeast is now in and I have a very nice white thin (yay enzymes) tangy/sweet slurry going.


Hello John,

Not to cause panic (buried in the forums is a discussion on toxicity), and I wish I had more solid information, when the mold starts to spore a different set of mold toxins are produced. To what degree I do not know, I just understand that once it goes green then the process enters a more hazardous zone.

Young sake in my readings can indicate a slight greenish tint which may or may not be attributed to over-ripe koji.

So all I am trying to say is… just be careful :slight_smile: Even if you knock off a slight spore layer, the substrate (the moldy rice) will have additional enzymes/acids that may not be compatible with human consumption…

Then again, you might have to eat 1/2lb of greenish rice to hurt you? dunno.
Sounds like the moto is doing its thing!

Noted and I’ve thought of that. And also noting that some toxins can be flavorless, so far it is tasting exactly like it should. And good to hear young sake in the makings can have a slight green tint.

Having watched this batch go fully to spore, what I’m using is didn’t go fully there. My gut feeling says it’s ok, but I will of course be careful.

It came to mind today that I can do better than ‘being careful’. In my previous incarnation I worked as an analytical organic chemist…organic acids being something I am familiar with.

I’ve been in contact with some lab associates and am putting together samples to send down for analysis of kojic acid in my raw rice (control negative), koji (sample), koji-kin (potential known positive) rice and sake (also sample) in process.

We will be extracting, making a derivative, and analyzing by GC/MS. I’ve got a little number crunching to do before hand to make sure what we can see is useful. That we don’t end up with a meaningless ‘non-detect’.

I’ll report back on what I find.

John, the alchemist and chemist :smiley:

After a couple hours searching and reading toxicity data for kojic acid, I used these pieces to base my extraction scheme on:

[quote]Because of these inhibitory properties on a variety of oxidases, Kojic acid has been
commercially used in Japan for many years as a food additive in fresh vegetables, crabs and
shrimps in order to maintain their freshness (antioxidant) and to inhibit discoloration, as a
preservative, as an antioxidant for fats and oils, in the preparation of derivative esters (i.e.
Kojic oleate, Kojic stearate), inadhesives, in chelate-forming resins and as a plant growthregulating agent to increase production, early maturing and increase sweetness. Kojic acid
has been used in flavourings at 0.2% to add lustre, to prevent discolouration on vegetables
at 1.0%, in flour production at 0.1%, in meat production at 0.2%, in syrup at 0.05%.

[quote]The LD50and its
95% confidence limits were calculated to be 1800 (1500 – 2000) mg/kg bw[/quote]

[quote]It was estimated that the no effect level of Kojic acid is 125 mg/kg bw/day when
administered orally to male rats over a period of 26 weeks. [/quote]

[quote]It was concluded that the NOAEL for thyroid tumour-promoting effect for Kojic acid is
0.03% or 15.5 mg/kg bw/day under experimentalconditions chosen and that the substance
possesses weak tumourigenic activity in rats due to continuous serum TSH stimulation by a
non-genotoxic mechanism. [/quote]

And most of that is from … GU&cad=rja

I rather find that first one a bit alarming…and comforting at the same time. It’s seeming like kojic acid is certainly toxic, but not alarmingly so at lower (less than 0.1%) concentrations with limited exposure.

Well, the samples are off to the lab. Sake, koji, rice and tane-koji. I had to make some assumptions about the detection limits on the instrumentation to get the extraction scheme going. We should easily be able to see 100 mg/L in the finished sake (0.001%) and 100 mg/kg (the level where wildly contaminated koji would produce a level of 0.1% in finished sake(‘additive level’)) for the solid samples. If all goes right, the references for instrument detection will be nicely dated, and we may be able to see 100 times lower than this. But either way, I believe I have it at a level to give meaningful data.

We will see.

Very interesting and would be great to see what the measurements are.

Thanks for checking it out.

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