As I understand it, The steam would be the “gelatinization” step for the rice.
The enzymes in Koji converts the starch to sugar just like the enzymes in the mash do. When you toss the koji into your mash it’ll just denature the koji enzymes and kill the Koji. It may give you flavor though since you are mixing the koji stuff in your mash
The honest answer is that you might maybe get a *bit* of flavor added by the koji, but it’s going to get bowled over by malt, hops, and yeast. You’d need to use a *significant* percentage for it to be noticeable.
The koji fungus is aspergillus, and it’s a natural source of Amyloglucosidase, the enzyme that converts starches to sugars. The exact same stuff you use to make a brut IPA or to dry out a beer. Since sake is not traditionally mashed, the koji is used to convert in lieu of diastatic amylase enzymes from malt.
By adding it to the mash, you’re either going to get that bonus conversion or just nuke it (highly temp sensitive) and get nothing out of it past fancy rice and time wasted. And unless you’re using a wild amount of unmodified malt and roasted barley, you’re not going to need the AMG for your mash.
When you’re talking about sours using koji, they’re predominately using it during secondary/during souring, where it’ll have more of an impact.
I’ve used it in a beer before, but only on a homebrew level. Instead of spending a ton of time steaming and inoculating, I just bought already koji’d rice bricks (Miyaki koji “malted rice”) and broke them up into my mash tun. I can only assume it did what I need it to do, but I went hard on the beer with sake yeast, fruit, and a light dryhopping so… past some conversion from the AMG and rice as a fermentable, who knows.
I've done this before, and I have no idea what batch size you're after, but just be prepared the process itself doesn't "scale" particularly well. Heat management is critical, as 5 degrees F of difference will result in a different enzymatic balance between Amalyse and Protease. So you can't just pile them up. You have to have a lot of trays, or way to keep the layers just a few inches deep while maintaining a consistent humidity and temperature.
It'll be 20HL(16 US BBL). Wass thinking of getting multiple perforated kitchen trays, lined with cheese cloth. Will probably be around 100kg to inoculate
Craft beer and sake brewer here: pretty much reinforce what has been said. You will denatured the enzymes in the mash, you will likely not get much flavor from the Koji unless its 20-30% of grist, and even then the earthy notes are subtle.
Best results I've had for both impact and flavor are using it in primary fermentation. Pretty amazing and wild stuff can develop there!
I have a beer fermenting now with 15kg koji rice in the fermenter, 10bbl batch size
It’s great, they always drop below zero so you gotta be careful, and never go above 7% or the lack of body makes the beer just taste like jet fuel. I feel like it even destroys a lot of the hop flavors as well so it’s great for a super dry lager
Ok maybe I shall consider adding a little into the fermentor. Guessing that Koji isn't gonna be an issue for cross contamination as its highly heat sensitive?
This is similar to the process that I've heard about from others who have made this sort of beer before. I agree that the steaming is the gelatinization step, what you're getting from the koji is the flavor of the ferment which - yes - does include a certain percentage of acid production.
There is white koji vs yellow koji. One of them produces citric acid and is meant to be used in other fermented beverages like beer and the other is used to make sake. If you don’t want the acidity, use the one that doesn’t create as much acid
I’m a brewer in Japan and I just did a collab with this method. We boiled the rice and just left it in for 24 hours
I don’t remember the % but it wasn’t huge but somehow we did get a touch of sake/koji flavor
DM if you need more details and I’ll send you the email of the guy we collabed with, he’s super nice and loves talking about it
I wasn’t there for that part cause it was the day before but my friend said he just cooked the rice in a rice cooker and then put it in the mash tun. When it got down to 40 he sprinkled koji (the mold, not the rice) on it and just let it sit overnight.
The next morning we just did the regular mash on top of it
As I understand it, The steam would be the “gelatinization” step for the rice. The enzymes in Koji converts the starch to sugar just like the enzymes in the mash do. When you toss the koji into your mash it’ll just denature the koji enzymes and kill the Koji. It may give you flavor though since you are mixing the koji stuff in your mash
The honest answer is that you might maybe get a *bit* of flavor added by the koji, but it’s going to get bowled over by malt, hops, and yeast. You’d need to use a *significant* percentage for it to be noticeable. The koji fungus is aspergillus, and it’s a natural source of Amyloglucosidase, the enzyme that converts starches to sugars. The exact same stuff you use to make a brut IPA or to dry out a beer. Since sake is not traditionally mashed, the koji is used to convert in lieu of diastatic amylase enzymes from malt. By adding it to the mash, you’re either going to get that bonus conversion or just nuke it (highly temp sensitive) and get nothing out of it past fancy rice and time wasted. And unless you’re using a wild amount of unmodified malt and roasted barley, you’re not going to need the AMG for your mash. When you’re talking about sours using koji, they’re predominately using it during secondary/during souring, where it’ll have more of an impact. I’ve used it in a beer before, but only on a homebrew level. Instead of spending a ton of time steaming and inoculating, I just bought already koji’d rice bricks (Miyaki koji “malted rice”) and broke them up into my mash tun. I can only assume it did what I need it to do, but I went hard on the beer with sake yeast, fruit, and a light dryhopping so… past some conversion from the AMG and rice as a fermentable, who knows.
I've done this before, and I have no idea what batch size you're after, but just be prepared the process itself doesn't "scale" particularly well. Heat management is critical, as 5 degrees F of difference will result in a different enzymatic balance between Amalyse and Protease. So you can't just pile them up. You have to have a lot of trays, or way to keep the layers just a few inches deep while maintaining a consistent humidity and temperature.
It'll be 20HL(16 US BBL). Wass thinking of getting multiple perforated kitchen trays, lined with cheese cloth. Will probably be around 100kg to inoculate
Craft beer and sake brewer here: pretty much reinforce what has been said. You will denatured the enzymes in the mash, you will likely not get much flavor from the Koji unless its 20-30% of grist, and even then the earthy notes are subtle. Best results I've had for both impact and flavor are using it in primary fermentation. Pretty amazing and wild stuff can develop there!
I have a beer fermenting now with 15kg koji rice in the fermenter, 10bbl batch size It’s great, they always drop below zero so you gotta be careful, and never go above 7% or the lack of body makes the beer just taste like jet fuel. I feel like it even destroys a lot of the hop flavors as well so it’s great for a super dry lager
Ok maybe I shall consider adding a little into the fermentor. Guessing that Koji isn't gonna be an issue for cross contamination as its highly heat sensitive?
Yeah it starts to die around 40c, and it’s not very strong anyways. We put 15kg in 10bbl but I heard if you put less it takes forever to finish
This is similar to the process that I've heard about from others who have made this sort of beer before. I agree that the steaming is the gelatinization step, what you're getting from the koji is the flavor of the ferment which - yes - does include a certain percentage of acid production.
There is white koji vs yellow koji. One of them produces citric acid and is meant to be used in other fermented beverages like beer and the other is used to make sake. If you don’t want the acidity, use the one that doesn’t create as much acid
I’m a brewer in Japan and I just did a collab with this method. We boiled the rice and just left it in for 24 hours I don’t remember the % but it wasn’t huge but somehow we did get a touch of sake/koji flavor DM if you need more details and I’ll send you the email of the guy we collabed with, he’s super nice and loves talking about it
Yeah I'd like to hear more, especially how you treated the rice
I wasn’t there for that part cause it was the day before but my friend said he just cooked the rice in a rice cooker and then put it in the mash tun. When it got down to 40 he sprinkled koji (the mold, not the rice) on it and just let it sit overnight. The next morning we just did the regular mash on top of it