This is part five of a series on making sake at home, part one is here.
After ten days of gently stirring and peering at our moto for ten days, it was time to build the main fermentation, or moromi. During the moromi, you add more rice, water and koji rice in stages as the alcohol level of the sake rises.
I lowered the temperature of our brew fridge to 15C, santised a 10L brewing bucket, and started steaming rice in bigger batches than before.
The method we followed was, again, from Advanced Brewing, the same site from which our koji kin came. I’ve simplified their instructions below.
Total ingredients for the moromi:
- 700g koji rice
- 2250g uncooked sushi rice
- all of the moto
Day 1: Steam 375g rice. Cool it and combine with 450ml of water, all of the moto and 150g koji rice in a sanitised 10 litre brewing bucket.
Stir thoroughly, then set aside to ferment at 10-15C. After about 15 hours stir gently* and stir again every few hours.
Day 2: Stir
Day 3: Steam 750g rice. Cool it and add it to the moromi with 225g grams koji rice and 1200ml of water. Mix well. After about ten hours stir,* then stir every few hours.
Day 4: Steam 1125g of rice. Cool it and add it to the moromi with 335g koji rice and 2250ml water, mix well. After about ten hours stir,* then stir every few hours.
Day 5-7: The fermentation will seem very active and frothy. Keep stirring. At around this time I started to notice a very pleasant, fruity-floral sake smell. Hopes rose!
Day 8: The fermentation will slow down, and the sake will smell increasingly alcoholic. The taste of ours was now less rice-sweet, more bitter and complex.
Days 9-20: Keep stirring, the alcohol levels will be rising and the yeast activity slowing.
By day 20 you will have something like 19% alcohol (though it’s impossible to know how much without fancy equipment), and the sake is ready to be strained.
*Vision Brewing and others are very deep into stirring schedules as combinations of delays, then regular stirring apparently “helps the yeast and alcohol production” in ways I don’t yet understand. I stirred the rice whenever I thought about it; more early on, when the rice formed a cap, then less in later days, as the rice degraded into a kind of soup. Never overnight or when I was off at work; I decided that was a bridge too far.
So far so good. It was time to press, pasteurise and bottle.