Experiments in sake making: From simple to syruping and doubling (Part 3)

By Christopher G. Prince

Part 1 of this article covered using Chinese yeast balls to make an alcoholic rice beverage, and Part 2 covered making koji rice. In this final part of the article, I cover my experiments using koji rice to make sake.

Using the koji rice in brewing

My initial forays into using koji rice in brewing sake were interesting, but hardly successful. I was still in the mode (and continued to be): How can I simplify? Do I really need complicated multi-rice additions described in recipes like this?

I made a few attempts, and here’s a recipe I followed. This uses koji rice and brews using a single step. I tried this and got a beverage that was palatable, perhaps better tasting than my Chinese yeast ball recipe, but had little alcohol. I don’t (yet) have a hydrometer or other instrument for measuring alcohol content (not expensive, I need to get one!) but I am a pretty good judge of a weak alcoholic beverage. I’m guessing the resulting beverage was lower than 5% alcohol.

Multiple rice additions

After having successfully grown my own koji rice, and done various (not very successful) experiments with trying to make sake using koji rice, I was ready to step up to the full-blown sake making process. I emphasize the method of multiple rice additions here because that seems critical. So far, I have been unable to get a high alcohol content beverage, using koji rice, without the use of a multiple rice addition method.

But, what is the multiple rice addition method? Unfortunately, it’s not just adding rice multiple times. The basics go like this:

First, you make the moto. You combine cooked rice with koji rice, yeast and water. And refrigerate for about 10 days. Moto is also called shubo or seed mash.

Second, and this is what I really think of as the “multiple rice addition”, you take the moto out of the fridge and across several days add both cooked rice and koji rice. You do this three times, each time adding both cooked rice and koji rice. By the end of these additions you have a strongly fermenting mixture!

I’m generally following this recipe (it also describes making the koji rice; I just happened to follow a different recipe — described above). Here’s the summary I have pasted in my brewing notebook:

More specifics:

a) I used a single Lalvin K1-V1116 dry yeast packet.

b) For each of these steps (not for the koji rice itself) I used regular cooked rice, made in a rice cooker. I am willing to be convinced otherwise, but this is simple (simpler than steamed rice) and seems to be working.

c) I had my koji rice in the freezer. I am taking the portion of that needed for the next step out of the freezer the night before to warm up to room temperature. While I didn’t do it, next time I plan to take the moto out of the fridge the night before. I think these warm-ups can get the fermentation action working more quickly.

d) I used the entire batch of koji rice I described above (based on 4 cups raw rice) across the various steps of the current recipe. Possibly too much, but I had it on hand and wanted to get rid of it.

I had a bit of a sake emergency the morning I added the rice and koji rice in the final step. When I added the rice and koji rice, I left about two inches of space below the top of my 2-gallon plastic fermentation tub. That was not enough! After about an hour here’s what happened:

Godzilla! :)

The fermenting rice literally blew the top of the container! With the lid off, this is what it looked like:

Make sure to leave about 25% of the top of your vessel free: I didn’t and paid the price!

No longer two inches of space from the top to the fermenting rice! 1/2 inch at best.

I think a better rule is to never fill up to within say 25% of the top of your fermentation vessel. This process would have been better in a 3- or 5-gallon vessel. On the positive side, the fermentation is really active! This is a good sign.

My main learning from this so far is that the multiple rice-addition method really works! It ferments well. I do need to taste the resulting beverage, but so far I’m sold.

I’ve seen this multiple rice-addition magic described as syruping:

In order to ensure a complete fermentation, it’s best not to add all of the rice and koji at once. Just like syruping a wine, gradually adding the fermentables coaxes the yeast into going above and beyond their usual alcohol tolerance. Rice, koji, and water are added three times over a period of four days.

And as doubling:

The doubling stage system, … allowed the ferment to develop much higher alcohol levels [to around 19% abv]. Until then one could produce sake only to about 9%abv. … Those early brewers found that they could use this initial sake as a starter mash, and then double the mash to start a real ferment, which was doubled again after a day of rest, and doubled twice more (a total of four doublings).

During the period after the third rice addition, the fermentation was strong, as evidenced by the good bubbling action. I often saw more than one bubble per second.

On 9/23/20, the day of the third rice addition (ultrafast bubbling!):

On 9/29/20. This was more typical of the period after the third rice addition:

Sake fermentation: The last day

On 10/9/20, I ran the results through my handy fine-mesh colander. Here’s what it looks like in that process:

Processing the final result through my colander

And:

The final result

The alcohol content is high, at least as high as what I’ve gotten out of using the Chinese yeast balls. The taste seems smoother, good and more cohesive (according to my wife). A better taste than the Chinese yeast ball procedure to my palate — less sharp. A definite success!! I’m next going to start making my koji incubator to get better temperature control when making the koji rice.

Conclusions

If you want a simple method, the Chinese yeast ball recipe is a pretty straightforward way to get a strong alcoholic beverage from rice. It does have its limitations though. You can vary the type of rice, the type of yeast ball, but so far the flavor that I’ve seen is pretty much the same — not bad, but pretty sharp.

To get more control, you need a fair amount more motivation. If you can find a good source of koji rice pre-made, you may be able to avoid that step. I enjoy cooking though, and am liking this step. The multi-rice additions after that seem necessary too to get a reasonably high alcohol content. I’ve been glad that I’ve leveled up and am making “serious sake”! :)

I still remain focused on figuring out the difference between steps you can ignore or leave until later and steps that are essential. Here are my thoughts to date:

Essentials:

  1. Use steamed rice when making the koji rice.
  2. Carefully control the temperature when you make the koji rice.
  3. The need for multiple rice additions.

Lower priority, or possible steps to ignore:

1. Rinsing the rice. Perhaps this is very trusting of me, but I’ve been skipping this. Implicitly I’m believing that the rice I get is clean. Possibly I’m too trusting of the rice manufacturers? Perhaps rinsing the rice has other impacts in the sake making process. Of course, I can’t ignore “rinsing” to some degree while making the steamed rice. A necessary step in steaming rice is to soak the rice, and the subsequent draining off of the water certainly constitutes one step of rinsing. Aside from that though, I’ve not been rinsing my rice.

2. Steaming the rice you use in the main fermentation steps. While I’m sold on steaming the rice I use in making the koji rice, I haven’t been steaming the rice I use otherwise. It adds time and complexity and I remain unconvinced as to why I ought to do it. I cook the rice using the standard boiling method, let it cool overnight, and then use it in my next rice addition or sake making step.

3. The type of white rice to use. Reading about sake making, you see a lot of opinion about this. And perhaps it makes a difference, in the final flavor or the amount of alcohol. So far I’m not worrying much about it though. I wouldn’t use Uncle Ben’s pre-cooked rice, but so far any general purpose white rice seems to work for me.

4. The type of yeast to use. This is for the koji-based process, and not the Chinese yeast ball process. I’ve been using wine yeast, but would like to try just bread yeast and see what the results yield. I am a big believer in using fresh yeast. I have made bread using old yeast and gotten poor results. I keep my sake yeast in the fridge, and my bread yeast in the freezer. So while I use fresh yeast and I treat it well, I remain unconvinced about the impact of specific types of yeast.

5. The temperature control used in the main fermenting steps. While I generally have been keeping my sake fermentation tub in the basement, and in my house that’s fairly cool, I’ve not been worrying too much about this. I definitely haven’t imposed any specific temperature control on the fermentation tub. I was interested to see that while making the moto in this koji-based sake making effort (described above), that fermentation was pretty active while the moto was in the fridge.

6. The need for yeast nutrients and citric (or lactic) acid. In my last sake batch, I did use yeast nutrients and some citric acid. I’m not sure if either of these are necessary, but they are relatively low cost and take little effort. The yeast nutrients are supposed to augment the food for the yeast — yeast doesn’t live on just sugar alone? But how much will your results vary without it? The citric acid is supposed to help eliminate unwanted molds or fungus in your fermentation. Again, I’m not sure.

7. The specific type of koji to use. I’ve heard some people talk about the importance of specific kinds of koji. I suspect this is where sake making turns into a fine art. And I’m a long ways away from having a palate that could appreciate the differences!

In closing I add one more observation. I’m now seeing the reason for either pasteurizing your resulting sake or refrigerating it or both. I left the jugs of my brew, resulting from the multiple rice addition method, out of the fridge and didn’t pasteurize them. And after a week, the taste isn’t quite so good any more! It’s sharper. Whoops! Not bad, but more like the taste of the previous Chinese yeast ball recipe. I’ve now got it in the fridge, and plan to both pasteurize and refrigerate my next batch.

Other Resources

A source of Chinese yeast balls from Canada. I’ve not tried these, but would like to (the shipping price is high).

How to make “sake” by micro brewing method: A relatively simple overview of the full sake making process.

Sometimes people buy their koji rice. Here’s a recipe if you do that.

Two possible sources of koji rice:
Cold Mountain Koji
homebrewsake.com

Another koji rice recipe (with a nice wooden koji rice box!)

Koji Propagation, with a step on spore generation
Another writeup on propagating koji spores
And see both https://www.organic-cultures.com/instructions_sheets/koji_rice_from_koji_spores and
https://controlledmold.com/growing-koji/

One of the few related active forums I’ve found. This one is on koji:
https://www.reddit.com/r/Koji/

A new sake-making forum:
https://groups.google.com/g/sakemaking

--

--

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store