Understanding Koji?

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twisted_times
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Understanding Koji?

Post by twisted_times »

So today and tonight I have been making my AG and reading up on my next batch of AG rice with Koji. I am just throwing thing out here to understand better.
I am in WA U.S. A local store sells Koji rice with A. Niger and oryzae in it also sells sake Lee's and soy koji.

I started off searching this site with the HD Google search and read till my brain is mush then went to a standard Google search. I came across this site. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4136118/" onclick="window.open(this.href);return false;" rel="nofollow
Some fairly heavy reading. The standard defining workings of Koji

I found another site that can not remember the name of that said Koji does not propogate like yeast. It grows by sending out spores when the original colony is subjected to stress, ideally by drying out of the rice.

So in theory putting an active colony of Koji rice that is slowly drying out next to all of your rice to be used in your grain bill will cause it to inoculate the new grain? Would this speed up the process of fermentation? A big consideration as the first webpage says it is 10-20 days for the first ferment before even adding it to the primary ferment which could run another 10-20 days. If it is not stressed and in ideal living conditions will it not grow and ferment slow due to small quantitys of kojis in the mash converting large quantities of starches and sugars in parralell?

So being like enzymes that do not reproduce when happy the more of the A. Niger and oryzae. Grown by stressing the Koji and forcing it to propogate could cause a higher and quicker conversion rate?
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hotmaildotcom1
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Re: Understanding Koji?

Post by hotmaildotcom1 »

Excellent source on the paper. It was a very good read! I'm not a pro on the topic by any means but I'm going to throw everything I've got at it.

I know that many bacteria and yeast go through distinctive stages in their life cycles as you've stated above. All of the enzymes that will be produced in the process are going to be unique to where those microorganisms are in their life cycles. I would imagine that the initial inoculation of the rice in this process would be almost inconsequential however in the overall time frame that is needed for the process as a whole.

I would imagine proper exposure to the spores used to create the initial environment would absolutely help secure the footing of those initial species present. However it is pretty evident from the linked paper that at each stage in the production of the final product, there is a completely unique microbiota present. I would imagine while some of those species present in stage one might be aiding in the breakdown of the rice (via enzyme or metabolic cycle of some other nature), many of the other species might not be. It could be the case though, that even though some species aren't directly metabolizing the rice into final product, they might be setting up the proper living conditions for the next microbiota that comes down the line in the production of the sake.

The reason I think the overall production might not speed up is because the original species that you are talking about stressing in order to speed up inoculation is indeed a fungus that reproduces via spores. However the paper that you referenced shows that throughout production of the final product the majority of the species present are bacteria. Most of those bacteria mentioned in the paper appear to be found on almost every surface, they just really enjoy this environment in particular so they reproduce more there. I might imagine that by increasing the amount of the fungal species present in step one, you might not increase the overall production as that fungus might play a minor role in setting the stage for step two. That or the fungus might contribute strongly to fifty percent of the overall environment needed for step two, but it would still need the bacterial growth in step one to catch up.

I do not remember how many steps there are in the production of sake from start to finish, but I do remember from reading prior to my own failure at sake that there are quite a few. If there were even one of the bottlenecks mentioned in my last blurb that could immediately retard the overall speed of production. And that's just if one bottleneck was present and there are many opportunities in such a long and concerted process for a bottleneck to develop. The reason I even thought of this as an issue to your hypothesis is because this "bottlenecking" is actually seen throughout a ton of biochemical mechanisms in all sorts of microorganisms and microbiota in general.

All of that being said, maybe the fungus present in step one would just make a ton of food for step two and you'd just throttle through the process as you suggested having given it that initial push. Still though; all of the digestion is going to occur on the surface of the rice. The species present can only penetrate that surface so far and so fast based on food content, moisture content, and overall quantity of the species present. I would imagine that this is one of the reasons that the rice is polished in higher quality sake as not only does it stop that outer layer from shedding into the product, but it allows for the more complete digestion of the rice that is left after polishing.

All and all I'm just making some guesses based on what I know about completely separate systems. Once again it was a great read though! Definitely a saved paper and a good thought process. You should give it a shot!
twisted_times
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Re: Understanding Koji?

Post by twisted_times »

Thank you for the great info hotmail. It seems as though you are quite correct. As reading more pages along with reading the first multiple times again that an over abundance of Koji in the primary ferment would cause an off balance of one thing or the other. This may cause multiple issues ranging from the ph to be off to a specific mirco to become more dominant in the ferment. So although a very different animal compared to other enzynes it reacts very similar. As with all grain. An over abundance of any particular component can prohibit proper ferments. The Saccharomyces cerevisiae (yeast) may not have the optimal living conditions to thrive.

https://meishu-no-yutaka.blogspot.com/2 ... lowed.html" onclick="window.open(this.href);return false;" rel="nofollow

This page goes through a pretty specific process of Koji kome production.

http://drinks.seriouseats.com/2011/02/s ... rains.html" onclick="window.open(this.href);return false;" rel="nofollow

This one goes more into Temps for sake fermentation Temps which suprisingly is very low compared to a standard grain. There is a little conflict as the last page describes an extreme amount of sterility in production environment but the previous ones describe spore saturation of work surfaces which in turn would help with the right strains if you will forming, I do not remember which page mentions workers not even allowed to eat certain food due to possible contamination of production spaces.

A very intriguing topic as a lot of sake has the ability to ferment to around 20% naturally with very little off flavors and bakers or lagers will only get to 12-14+-. And if pushed to hard will create odd results. Curious as to if using a Koji kome in. American grains with a highly controlled ferment could result in a 20% yeild without off flavors.
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hotmaildotcom1
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Re: Understanding Koji?

Post by hotmaildotcom1 »

I'll have to get around to getting on those other articles some time soon. I agree that seeing the low temps is pretty surprising, but if I remember right it is a very long process. Immediately what comes to mind are cold lagered beers which I know also use low temps and long fermentation processes.

I understand the fascination with sake as I had one last year about this time. I tried three batches while doing increasing research after each failure. While they all made some product it definitely wasn't something I was going to be very excited about. I started going around and purchasing different grades and qualities of sake to even see if it was worth trying that hard over and decided against it in the long run. I was just starting to understand how much treating my mash well was effecting my end spirits, so I abandoned half assing things. It is a very involved process for what I considered the end result to be worth. Still though, it is very interesting. I still really enjoy reading about the process as it's pretty damn cool.

Regarding your suggestion that other grains be inoculated with the koji fungus; I honestly have no idea. This paper you provided is the first reading I have done as to the different species other than yeast that are normally present in a ferment. I would assume, with no justification I might add, that the species present in the sake ferment though might be very similar to those found in your average beer or mash ferment. I'll run it buy some of the brewing program guys that I go to school with if I see them in the building at all and see what they have to say about it.

Finally on the subject of high ABV yielding fermentation. I don't know why but this definitely tickles my interest more than a little bit. I recently found out about the power of specifically bred yeast, rather than my off the shelf bread yeast. I started using champagne yeast in almost everything I make, as it is known to go as high as 25% ABV in highly controlled environments. With little to no effort however I get about 14% to 17% from the little suckers and that's in fermentation with little nutritional value. If koji had the ability to ferment other grains as well as they do sake rice, that indeed could get pretty high ABV wise. I would be pretty stoked to see it happen. It's all such a long process though and without a cleanroom of some sort it would be very hard to pull off without contamination I think. Also you could always get it as high as possible in the fermenter without creating those off tastes, and then go see what the spirit taste like!
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DenisO
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Re: Understanding Koji?

Post by DenisO »

Does anyone successfully got any flavored product with Koji?
Please share your experience
I'm still getting not bad smell mash, but no flavor in product (or smell like medicine)
I'm using pot still for first distillation and reflux 500 mm column, for cut distillation
Will try use pot still only next time
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