On Making Sake

Recently Douglas and I thought it would be a great idea to offer a one gallon Sake making kit with our friends at Kato Sake Works in Bushwick, as part of our NYC Brewery Series. We have been friends with the owner and founder, Shinobu Kato for a few years. We’ve even had Shinobu on our podcast (See What You Can Brew) extolling the virtues of sake. We’re generally bullish on him as a person as he is an extremely nice guy, and his sake is fantastic as well.

We contacted Shinobu and he was very happy to offer us a recipe and instructions under one condition, we had to make it ourselves first. As we are inveterate experimenters when it comes to brewing, we heartily agreed. We both made the same recipe so we could do a taste comparison. Shinobu supplied us with the 6.6 lbs of polished rice needed to make one gallon of sake, as we had everything else we needed at the shop.

While there are many different types of sake (see here for more info on the varieties of sake), the type we were making is referred to as “Junmai” which broadly means pure rice sake. The alcohol by volume typically varies between 14 and 18% and is meant to be consumed cold.

Making the Koji Rice (Kome-koji)

The first step in the process was to make Koji rice (Kome-koji), sometimes also called malt rice. The rice must be steamed before adding the Koji mold. This requires thoroughly rinsing about a quarter of the polished rice (~1.6 lbs) and then soaking it in cool water for an hour and a half. After soaking, let it drain in a sieve for around 20 minutes to drain off excess water.

The next step was to steam the rice for one hour. I wrapped the rice in a clean cotton cloth to avoid condensation dripping on it, put it in a large colander and suspended it over a pot of boiling water with a lid on top for one hour. It’s important that the rice does not touch the boiling water, it has to be steamed, not boiled. If you have a large rice steamer you will have an easier time than I did, but it really wasn’t that hard. I knew the rice was finished when it was both translucent and chewy in texture.

Steaming Rice Steaming Koji Rice Steamed Rice

I cooled the rice down to 86˚F (30˚C) and put it in a stainless steel bowl. I sprinkled 3 grams of Koji mold (Koji-Kin) evenly across the rice. Then I put the bowl of soon to be Koji rice in my oven without turning the gas on. I put a thermometer in the rice and checked it periodically to make sure it stayed at 86˚F. I kept the oven door slightly ajar and was able to maintain the temperature pretty well. After about 40 hours the rice was covered with a fine white mold, it was now Koji rice!
This may seem like a lot to do, but it is mostly a lot of waiting and is a very important step in the whole process.

Koji Starter Moldy Koji Rice

If you’re familiar with mashing malted barley for beer, then you’ll see the similarities between the two processes. Koji mold converts the rice starch to sugar just like mashing malted barley does in beer making. The big difference is that the Koji rice is added to more steamed rice and water along with lager yeast. As the mold breaks the starch into sugar the yeast consumes the sugar and creates alcohol. This happens concurrently allowing the yeast to adapt slowly to the alcohol in its environment making it able to ferment higher levels of sugar and survive in more alcohol than it normally can. Typically beer yeasts start stalling out once they reach between 10-12% ABV, but Sake can climb up to 18% due to the addition of the koji mold.

Perfect your Rice Steaming Skills

Once I had the Koji mold ready it was time to…steam more rice. Five pounds of it! I was able to do this in a larger strainer over a larger pot, but if you don’t have a big enough steamer you can do it in batches. The process is the same, rinse, soak, drain, and steam. While I was busy steaming the remaining rice, I used that time to prepare for fermentation. I added the following to a sanitized, 2 gallon food-grade plastic bucket (with lid, to be used later):

  • 1 Gallon Water
  • 1 Pack Saflager 34/70 Yeast
  • 1.5ml Lactic Acid OR 3 grams Citric Acid
  • 1.6 lbs Kome-Koji Rice (the previously “koji’d” rice)

We add the acid specifically to help keep any spoilage bacteria from forming during fermentation (bacteria don’t like acidic environments). Once the 5 pounds of rice was finished steaming I cooled it down to room temperature (68˚F, 20˚C). I then added the cooled steamed rice to the water mixture and gently stirred it with a large sanitized steel spoon until all of the rice was submerged. It will be very thick and difficult to mix, so be prepared to get a small workout.

Once everything was mixed well, I covered the bucket lightly with a lid. Making sake starts with an open fermentation so I kept the lid loose. After a few hours the rice absorbed the water and became pretty solid. Doing my best to not break the rice up too much, I stirred the mixture every 6 hours. After a while the Koji mold starts breaking down the rice and liquifying it. It literally turns from a semi-solid into a mostly liquid form as the rice breaks down, which is pretty cool! Each time I stirred I made sure I kept the rice below the water line to prevent any contamination. After about 2 days it was obvious the entire batch had liquified. Now fermentation could begin!

Sake rice, koji, water and yeast Liquification

Slow, cool fermentation makes the best sake, which is why we used lager yeast. I put the loosely covered fermenter into my wine cooler at 50˚F, stirring it once a day. I put a small cookie sheet under the fermenter to catch any spillover from fermentation. Good thing I did because it bubbled over after the first few days. I kept the outside of the fermenter clean by wiping it with a paper towel soaked in star san solution.

Fermenting Sake in Fridge Fermenting Sake Fermented Sake After 6 Weeks

I stirred the sake every day and watched it ferment and bubble. I waited until there was no noticeable sign of fermentation (about 6 weeks) and then let it sit another two weeks just in case. I tasted it along the way and I was surprised and impressed at how good it was tasting! With beer we usually know when fermentation is complete because we know the Original Gravity and the estimated Final Gravity. There is no easy way to know your ABV (alcohol by volume) with sake as it is fermenting at the same time as starch conversion, and therefore no “true” Original Gravity. There is a calculator that can get you a pretty good approximation of your ABV, but it requires taking both a hydrometer and refractometer reading once your fermentation is complete. My sake came out to 14% ABV.

Once fermentation was finished I could have drank the sake if I felt so inclined. Unfiltered sake is called Doburoku, and it is delicious, but I wanted to experience the whole process and get as much sake out as I could after waiting so long.

I could have just poured the sake into a mesh bag and squeezed it by hand into another vessel and then bottled it, but Shinobu told me my yield would be less. After all this time I wanted as much sake as I could get! I procured another 2 gallon bucket and drilled a bunch of small holes in the bottom. I then poured my sake out of my fermenter into a clean pot, cleaned my fermenting bucket out and put the bucket with the holes drilled in it into the fermenting bucket (and sanitized both buckets).

Makeshift Sake Press Transfering Sake to Press Bag Pressing Sake

They were the same size so they stacked. I then took the sake and poured it into a mesh bag in the drilled bucket. I folded the bag over and put another bucket on top with a 20 pound weight as a press. I put a siphon hose on the fermenter spigot and pressed the sake into a one gallon glass jar. I let this go for two days, occasionally flipping the bag of sake over so I pressed every grain. I yielded almost a full gallon of sake in a one gallon jug. It was still somewhat cloudy but no large chunks. I realized while I was doing this method that I could have also put the bag with the sake in it into a colander with a lid and weight on it and pressed it into a pot.

Transfering Sake to Jug Transfered Sake

I could have bottled it right then but I wanted it to be clear so I capped the gallon jug and put it in the fridge for a few days until the sediment settled out (also known as “cold-crashing”). Then I simply siphoned the clear sake into bottles which yielded about 3 quarts. I also bottled the cloudy stuff at the bottom because I wanted to see if it was appreciably different. Shinobu told me that the finished sake would not be shelf stable for very long so I had to either drink it quickly, or pasteurize it. If I didn’t pasteurize it it would eventually go sour or become dangerously over-carbonated (i.e. a “bottle-bomb”). So, I opted for pasteurization - which was pretty easy and meant I could enjoy my sake at a reasonable pace.

After I bottled the sake and before I capped the bottles I put the bottles into a pot of boiling water with a thermometer in one of them. Once the sake got to 150˚F I turned off the heat and let it sit for one minute. I then covered the top of the bottles with some foil and let it cool down on my kitchen counter until it was cool to the touch. Then I put it in my fridge to get cold. Once they were cold I capped the bottles.

Pasteurizing Sake Cooling Pasteurized Sake

And there you have it, I had successfully made a gallon of super delicious sake. Unlike the stuff they heat in restaurants in the United States (which Shinobu informed me is usually used for cooking rather than drinking in Japan), my sake was smooth, and slightly sweet with rice aromatics.

Shinobu brought some of the one gallon batch sake he made at the same time as me to our monthly beer swap and I poured the sake that I made. Everyone was really impressed that I could make something almost as good as Shinobu, especially for the first time.

I highly recommend making your own sake, it takes time and some dedication but it is fun and is quite delicious. Learning the process has really informed my appreciation of sake as well - I’ll never look at it in the same way again!

Glass of Sake

Thank you to Shinobu and Kato sake works for all of their help throughout this project.

John LaPolla