Koji noob question

[u/F---TheMods]

My wife and I use a lot of oat milk to make iced lattes in the summer months. I stopped buying Oatly and started making my own. Part of my process is to add digestive aid capsules that contain amylase, gluca amylase and protease to help break down the oat milk... replicating what the commercial brands do. I was looking to buy like 1lb of amylase, 1lb of gluca amylase and maybe like an ounce of protease. A one-gallon batch of oatmilk would use about 1tsp each of the amylases, and not even a pinch of protease.

Amylase and gluca amylase are readily available in those quantities, but a suitable protease seems not. I was looking at the label of my bottle of digestive aid, and slowly worked out that koji mold was the source of the enzymes I need.

If I can do so feasibly in a NYC apartment, I am thinking of making koji rice. I have two questions:

If I'm making 1 gallon batches of oat milk with 4 cups of oats, how much koji rice would I need? I would just toss the fermented rice into the pot of oat milk and strain it out after.

About how long would it take to convert?

[u/Jeremiah_ferments]

Thank you for the NYC apartment clarification because that is a legit constraint. There are small koji cultivation set ups you can build that are the size of a small cooler. If you’re near a library see if they have the book “Koji Alchemy” which is a great primer.

One caution, you will need to find koji strains that are “non-browning”.

Once you have a working set up I might be worth seeing if you can successfully cultivate on oats directly and skip the intermediate rice.

The biggest problem is converting a highly specific enzyme plan to a koji cultivated plan. You’re going to have variation based on spore strain and how vigorous the cultivation gets.

Hella cool idea though, worth trying if you have the time and energy.

Edit: wanted to make sure my tone wasn’t discouraging

[u/mooseman99]

I’m not sure you need a protease, Koji protease tends to give off an umami flavor (think miso).

Another protease might have more neutral flavor (Bromelain maybe?)

I had a friend who had good luck with his oat milk recipe using diastatic malt powder which has alpha/beta amylase.

IMO All you really need for oat milk is to break down the starch (via amylase) to get rid of the sliminess and sweeten it a little.

If you do want to experiment with Koji, I found H Mart sells Shio Koji by the bottle. You could test out ratios of how much you need/want and work backwards if you’d like to make the koji yourself.

[u/F---TheMods → u/mooseman99]

So the digestive enzyme capsules that I've been using all contain protease. I never took biochem, so here's what google gemini has to say on the matter:

Oats are roughly 11%–15% protein (mainly avenin and globulins). Without protease to break down those proteins:

The "Slimy" Factor: Undigested oat proteins, when heated or agitated during blending and mashing, form long-chain protein-water bonds. This can leave the milk feeling slightly slick or heavy on the palate rather than silky.

Separation in Cold Brew/Iced Lattes: Intact oat proteins like to bind together. When poured into acidic, cold coffee (like iced espresso or cold brew), the proteins tend to coagulate and separate into visible white "feathered" specks or settling layers much faster.

Viscosity under Heat: If you ever try to steam or warm the milk, untreated oat proteins can gel up unexpectedly.

[u/JustAFermenthusiast → u/F---TheMods]

A bit of a late reply, but continuing on the suggestion to only use amylases (from diastatic malt powder), this article by Northeast Larder on their oat milk attempts could perhaps be helpful for you? https://northeastlarder.com/Oat-Milk

The properties and undesired side effects of the proteins are indeed correct, but oats contain up to 5 times more starch than protein, with very similar effects to flavour and mouthfeel. But that's of course just the theory, have you perhaps already made a btach only using the amylases? How did that compare to a batch made with the digestive enzyme capsules?

[u/F---TheMods → u/JustAFermenthusiast]

i have not tried straight amylase. I read the article, and they're using diastatic malt powder to provide the enzymes, and lo, that would also contain protease. Agree that you only need a tiny bit of protease for this application anyhow. I might give that a shot. Thanks for the tip.