New substrates – Oats koji


Growing koji on new substrates

    As growing koji on new innovative substrates (raw meat, fruits and vegetables) is being viral, I decided to jump on the bandwagon.  Although I have to admit my challenge is a bit low key…

    The substrates I have chosen are

       A: Roasted buckwheat
       B: Polished wheat
       C:  Steel cut oats

Problem, in case of oats

    They all have different tricky points.   Let’s tackle with oats first.    Koji stands no chance on unpolished oats groats. Koji’s mycelium is tender and the surface of oats groats is  way too hard for them to penetrate into. Brown rice bran is too hard and it need to be germinated before growing koji on it. However, not like rice, wheats and barleys can be over-soaked which makes it difficult to grow koji under good control. Because the appearance of oats is analogous to wheats and barleys, I guess oats can also be over-soaked. Oatmeal is likely to be too soggy and mushy when steamed.

    I have done some research and found that there is another form of oats available called steel cut oats. I thought this is it! My problem solved.

However, to my disappointment, soaked and steamed steel cut oats are too sticky for my (koji’s) liking. Koji can’t breeze on it.  Well, koji is quite fussy grower.
Also koji (mold) is slow growing compared to bacteria or yeast and, by time koji is ready to flourish, the oats will be filled with other types of microbe. So there would be no space for koji to grow…
Koji requires nutrition, temperature, oxygen, moisture (NB: not water!). Among these four conditions, I envisage “Oxygen” and possibly “Moisture” could be tricky factor.

Consideration and assumption

    So I have decided to borrow the idea of using roasted barley powder I use when I make soybean koji. Soybeans are slimy after steaming. If you grow koji on slimy surface of soybeans, natto bacteria would definitely dominate on soybean surface. After all, natto is a wild extremophile where as koji is a sheltered microbe which requires tender care. Koji would stand no chance. (I heard many horror stories that you intended to make soybean koji, end up with having natto…) In order to prevent this happens and give koji a clear advantage, steamed soybeans are mixed with roasted barley powder (so that excess water is soaked) before the inoculation. I am pretty sure this would work as my solution for oats.

    Instead of using roasted barley powder, I used roasted and powdered oatmeal because then I need only one ingredient. Make it simple. So first I mixed oatmeal powder with koji spores and then sprinkled them on steamed oats.



      Below is the picture taken 48 hours after, proving my assumption worked nicely!

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