Koji is very important to Sake. Just like with Beers you take grains and use Amylase enzymes from malted Barley to convert the Starches/carbohydrates into simpler sugars for fermentation. Koji is what you use instead of malted barley or amylase extracts. Koji does not use amylase but rather has a natural mold that converts carbohydrates into simple sugars.
Here is a better one step method for making Sake:
rice cooker, pot and steamer, or even a regular pot
1 gallon Jar/bucket/carboy…
4 cups rice (short grain japanese rice preferred)
1 cup koji
yeast (Wyeast Sake yeast preferred, beer or wine yeast is second best bet. Brewers yeast is highly not recommended because it may not survive the fermentation process which may allow other spoilage organisims to come in and ruin the Sake)
water (Very clean tasting water is important for Sake, I would spend the money on good spring/mineral water for this. Fiji water would be great for this. Make sure and NOT use distilled or reverse osmosis water.)
Nutrients (This is optional but highly recommended, see below on nutrient additions.)
1 gallon recipe and instructions
In the fridge submerge 4 cups of un-cooked rice in water for 8 hours exactly. Too long and the rice falls apart and too early makes it too hard for the Koji to work on. This all effects the flavor of the end product. Next strain the rice and allow to drip dry for 30 minutes and then steam the rice for 45 min. Steam helps to gelatinize the starches while also hardening the outside of the rice which makes a longer ferment, the longer the better. You can however use a rice cooker or pot and water; you will just have a cleaner taste with steamed rice.
Once the rice is cooled add it to your 1 gallon jug. Add in your water to about ¾ of the container. Add in your 1 cup of Koji next. Cap off the container and shake it a lot for 2 – 3 minutes. You will need plenty of oxygen added to the must at this point. Top off with water to one gallon & add nutrients if chosen to do so. Allow this to sit in a warm place for 2 days. After the mold on the Koji has done most of its work over the last two days you can now pitch your yeast & add an airlock.
(Like I said nutrients are optional but recommended because water and rice has very little nutrients. If you can not order online or find a home brew store with commercial nutrients then you have other options. Take 3 TBS of bread yeast and boil it on high in two cups of your spring water for 30 minutes along with 10 fine chopped raisins. Pour the resulting mixture lack the raisins into the must. If you are not using Spring/Mineral water then add in one pinch of Epsom salt and 1/4 tsp of “Morton salt substitute” which is potassium chloride)
This next part is very hard for some people but is a must for clean tasting Sake. The Sake should be cooled to 50*F – 55*F when yeast is pitched and kept there precisely for the duration of the fermentation. the closer to 50*F the better. You also want very little sunlight to hit the container so it should be in a dark place but not completely devoid of light. Since you are using a mold from the Koji to convert the carbohydrates you do not want that mold growing too much. The enzymes it produces in the earlier stages of rehydration is enough to get the job done. If you leave the must too warm and there is too much sunlight the mold on the Koji will start producing different enzymes and produce acids from reproduction creating a tangy & sourer taste to the end product.
The total fermentation time should take 2 – 3 weeks. You will know when this is done when the liquid clears and all the spent rice bits and yeast are at the bottom. Siphon off the lees and place in a secondary container. This should be refrigerated to help preserve and allow more sediment to drop out. Several days later you should be able to bottle. Enjoy the Sake over the next month. If you want to age it then pasteurize the bottles by placing in water that is at 150*F for 10 min but making sure to not let the glasses hit the bottom of your pot which may be hotter. If you want to add some back sweetening then you can pasteurize and add a half a tsp of white sugar or dextrose per 12oz bottle to taste.
Originally Posted by the-martian-gringo
And that's the other reason I chose rice wine, I don't have to buy a bunch of fancy equipment or let it age for a super long time. It takes less than a day to make and it's ready for consumption in about a month!
Hahaha.....Sorry...... Sake is one of the most complicated fermentation processes I know of. The above instructions and ingredients are a cut corner but decent way of making Sake. Any less steps than above and you will have a sour liquid of 2% - 3% ABV that you are disapointed with. If you really want a quick and easy drink then look up JAOM. "Joes Ancent Orange Mead" It uses all ingredients at the super market and is drinkable in 3 months. There are many wine recipes that use juice concentrate that ferment quickly and are "drinkable" in a month if done correctly. I think Sake is cool so would suggest you read a lot more about it and give it a try. Take a look at the following web site that is probably one of the best guides on Sake I have ever seen.
Hope I popped no bubbles and wish you luck.