The Process

Making Sake, Part II – The Actual Process

Ok, step-by-step, here’s how to make a batch of sake.

Moto (酛)
(Total time: 14 days)

  1. Prepare 2.5 cups (600 ml) of cold water by adding 0.75 tsp (4 gm) yeast nutrient and a pinch (0.7 gm) of Epsom salt and stirring until completely dissolved. Then add 0.5 cup (118 ml) of koji and stir it into the water. Put this into the fridge at the same time as you put your rice to soak for steaming.

    If you want to use the shubo method of starter by adding acid to lower the pH, add 1 teaspoon (3.8 ml) of 88% lactic acid solution to the water used in the above step.

  2. Prepare 1.5 cups (355 ml) of rice as described on page 6 (wash, soak, steam).

  3. After steaming, add the hot rice to the cold koji and water mixture in your fermenter (there’s no reason to use an intermediate vessel here) to produce a starting temperature of about 74ºF (23ºC). Mix well with a sanitized spoon, and put this fermenter somewhere where it will remain at this temperature for the next couple days. Stir twice a day with a sanitized spoon. In the first few hours the rice will soak up almost all of the liquid (see image), but after 48 hours the koji enzymes will cause the rice to liquefy again.

  4. After two days, cool to 50-60ºF (10-15ºC) and add the yeast on top. Cover and let stand for 12 hours. The cool temperature at this stage is very important (sake yeast is a lager yeast) – remember the sour flavors I mentioned earlier? Move the fermenter to your basement or into a temperature-controlled refrigerator.

  5. After 12 hours have gone by, allow the temperature to come back up to 68-72ºF (20-22ºC) and stir the moto mixture with a sanitized spoon. Stir twice a day for 3 days, then once a day for three more days.

  6. The basic ferment of the moto is now finished, and the temperature should again be lowered to 50ºF (10ºC). Allow the moto to rest for 5 more days. Now you are ready for moromi fermentation!

    If you’ve added lactic acid for a shubo style starter, then you can skip this second week of resting the moto at cooler temperatures and just move on to the moromi buildup.

Moromi (醪) and Odori (踊)
(Total time: 26 days)

Fred Ekhardt wrote in his book:

The moromi ferment will be a three-stage buildup over a four day period. The slow buildup is necessary to ensure a maximum alcohol content. The stages, or additions, are called first addition (hatsuzoe), middle addition (nakazoe), and tomezoe or last addition. Each consists of a further portion of koji, steamed rice, and water. These sequential additions each double the volume of the mash until the full ferment can take place over about three weeks.

I realize that the timetable of additions I describe here can be a little bit confusing. What we’re doing is adding 3 rice additions over 4 days and each addition is going to double the total volume of our moromi. I’ve worked up this handy little example image to illustrate how this would look on a calendar.

Hatsuzoe (初添): (Day 1 – 2)

  1. Day -1: The night before you expect to add this addition (that’s going to be on the 14th day of the moto), wash and soak 2.5 cups (591 ml) of rice in cold water. At the same time, add 1 cup (237 ml) of koji to the moto, which has now been working for 2 weeks. Stir the koji in with a sanitized spoon.

  2. Day 1: After soaking, prepare the rice with the usual steaming method. While the rice is steaming, dissolve 1.25 teaspoon (7.0 gm) of Morton salt substitute (or potassium chloride) in a little warm water, then add more cold water to make a total of 2.75 cups (650 ml). Stash this in the fridge to chill.

  3. Day 1: When finished steaming, de-pan the rice and add the above mentioned chilled water addition. Mix thoroughly with your clean hands, making sure to break up any clumps you find. When the rice gets down below 85ºF (29.5ºC), add it to the moto.

  4. Day 1 – 2: At this point you can switch to a very large and well-sanitized spoon. Once the rice and water mixture is added to the moto, stir the whole thing thoroughly and vigorously. This should take you 15 minutes or so, the goal here is to aerate the contents of your fermenter so that the yeast cells have ready access to the oxygen they need for the reproduction phase that is about to start. Yes, I know this is a lot of stirring, but I promise you this is the last time you’ll have to do it. After this, aeration is no longer required. When you’re done, put the lid and airlock back on and keep the temperature at around 70ºF (21ºC). Stir with a sanitized spoon at 2 hour intervals for the next 12 hours, then twice a day for the next 2 days. You have now tripled the volume of your original moto.

Nakazoe (仲添): (Day 2 – 3)

  1. Day 2: 12-18 hours early, wash and soak 6 cups (1.42 L) of rice. At the same time, add 1.5 cups (355 ml) of koji to the fermenter. Stir it in with a sanitized spoon.

  2. Day 3: Steam your rice as usual. Then de-pan the hot steamed rice and add 8.75 cups (2.1 L) of very cold water. Mix with your clean hands to break up all the clumps, then add the whole thing to the fermenter. Again, switch to your giant, sanitized spoon and stir thoroughly.

  3. Day 3: Put the lid back on, keep the temperature at about 70ºF (21.5ºC), and stir it up after 12 hours. By now your volume is about 2 gallons (7.6 L).

Tomezoe (留添): (Day 3 – 4)

  1. Day 3: After you stir the mash up in the last step, add all of the remaining 20 oz of koji (570 gm) (if you made your own koji, you’ll need 3 cups [710 ml] of it here) to the moromi and stir it in. At the same time, wash and soak the remaining 5 pounds (2.27 kg) of rice.

  2. Day 4: The next day, 24 hours after starting the nakazoe step, steam your rice (in batches if necessary, this is a lot of rice). Add 1 gallon + 1 cup (4.3 L) of cold water to the hot steamed rice to cool it down, break up the clumps with your clean hands, and add the whole lot to the moromi. Then break out the giant sanitized spoon and mix thoroughly into the moromi. This will again double your volume to around 3.5 gallons (13.25 liters). Leave this alone at 70ºF (21ºC) overnight. At this time you can observe odori – the dancing ferment. This bubbling action of happy yeasties is a familiar sight to anyone who has made their own beer or wine before.

I receive a lot of e-mail and forum questions about the subject of yeast foam jumping out of the fermenter – sometimes explosively! – at this point in the process. Well, different yeast strains make different degrees of foam, but they all make foam during fermentation and this fact was taken into consideration when I recommended the commonly available 6 gallon bucket as the fermenter of choice for this size batch of sake.

The fact is, if you’re using really fresh yeast, really fresh homemade koji, and have gotten all of your moto steps right, then having a crop of yeast in your starter that are healthy enough to make some serious foam is perfectly normal. In fact, this is actually a desirable sign of a healthy fermentation! As long as your fermenter isn’t over-full, then the measure you should take to calm that foam down at this point in the process is to simply cool the fermenter down immediately. If you open the fermenter to add that final addition of rice and you see this, then skip the final overnight 70ºF (21ºC) rest and move your fermenter into the fridge (or whatever temperature control solution you’re using) and get it down to 50ºF (10ºC) right after adding the final dose of rice.

The overnight warm temperature rest is only there to give the fermentation a chance to really get going, and can be skipped at the brewer’s discretion.

From the fifth day on, you want to maintain a cooler temperature for the fermentation. After the room-temperature overnight period between days 4 and 5, you should chill it down to as close to 50ºF (10ºC) as you can get, or at least keep it between 45ºF (7.2ºC) and 55ºF (12.7ºC). Believe me, you want to ferment this cool. A warm sake fermentation can lead to some funky flavors, so try to avoid it. This is why the Japanese traditionally only made sake during the cold winter months, which is why this is called the kan-zukuri (寒作り) or “cold-brewed” method. Stir at 12 hour intervals through the 6th day, then leave it alone for the next three weeks. Somewhere between day 19 and day 21, the fermentation should pretty much be over (a hydrometer would read at 1.000 or less at this point). Note that, since there’s no way to determine an original gravity for sake, it’s not really possible to calculate ABV for the product. You’ll know it’s alcoholic when you taste it, though!

Ok, on to the next step:

Yodan (四段)
(Total time: a few hours to a day)

The “stabilizing addition.” I really only mention this for sake of completeness, as I always skip any post-fermentation additions because I prefer the driest and most alcoholic sake possible. There are two ways you can go here: you can add water to decrease the alcoholic strength of the product, or you can add koji and/or rice to sweeten the sake. Here are the calculated water additions:

  • 0 fl. oz. – If you add no water in this step, the sake should finish with an alcohol content above 18.5% ABV. This is genshu sake (原酒).

  • 30 fl. oz. (0.89 L) – This will yield about 16% ABV, which we could call “ordinary” sake.

  • 68 fl. oz. (2 L) – The alcohol level will decrease to about 14% ABV.

  • 120 fl. oz. (3.5 L) – Add just under a gallon of water and you’ll be down to about 12% ABV, which is the usual strength of fruit-flavored sakes.

  • 178 fl. oz. (5.25 L) – This will yield 10-11% ABV, which is low enough to allow you to prime and bottle condition the sake for a carbonated product.

Why would you do this? Beats me, I’m just parroting the math. I’ve never done any of these water additions.

Last, but certainly not least, adding 2 cups (473 ml)(uncooked amount) of steamed rice and 1/2 cup (118 ml) of koji to the sake at this point will add more sugar than the yeast can ferment, which will sweeten the sake. This amount of rice and koji will produce a very sweet sake called mirin, which is used in Japanese cooking to make such things as teriyaki sauce. Basically, the Japanese tend to use mirin in place of sugar wherever a sweetener is needed. If you prefer your sake to be sweeter, but not so sweet as mirin, you can decrease the amount of rice (or omit it entirely, just adding koji will add body and a little sweetness) added in this step. Obviously this kind of fine-tuning will require some trial and error on the brewer’s part.