Pressing – Joso (上槽)
(Total time: a few hours)
If you made no additions at yodan, then it is now time for joso – the pressing of the moromi. Clean and sanitize three one-gallon jugs, a small (1-2 qt range) stainless steel or other non-reactive pot with a handle (you’ll be using this as a dipper), a nylon paint straining bag (or a natural cotton canvas joso bag like the Japanese use), your standard bottling bucket, and one-hole stoppers with airlocks for each of the jugs.
How you go about doing your pressing is up to you, but here is one method I’ve used: Line your bottling bucket with the straining bag, then use your sanitized dipper to carefully ladle out as much of the moromi as your joso bag will hold and use your hands to press as much nigorizake out of the moromi as you can (if you have a small fruit press this will be a lot easier, though your method will obviously differ considerably).
Another method that is still used by certain artisanal kura is to not actively press your sake at all. Simply transfer your moromi to a straining bag, then suspend it over your bottling bucket so that the bottom of the bag will not touch the sake that drains out and let gravity and time do the rest. This obviously requires some patience and a very clean environment, but it’s another option to consider.
After the pressing is done, it’s a simple matter to open the valve on your bottling bucket and fill your sanitized jugs. Leave a little head space in the jugs and close them with your one-hole stoppers and appropriate airlocks.
If you want some nigorizake (cloudy sake) from this batch, this is a good (but not the only) time to draw off, bottle, and pasteurize some. See how that works? You don’t have to commit an entire batch to it!
(Total time: up to 14 days)
Affix stoppers and airlocks to these jugs, then keep them right at that 50ºF (10ºC) temperature for the next couple weeks. This will allow any residual fermentation to finish up and will allow the rice solids and yeast to settle out, leaving your sake relatively clear.
If you intend to make a fruit-flavored sake by adding fruit juice or puree, this would be the appropriate time to add it.
At this point you could just put a tight lid on your jugs of sake and store it in your fridge for anywhere from 2 weeks to a month before you drink it all. This is called nama sake, and I seriously don’t recommend doing this with an entire batch because any longer and lactobacillus can and will take over and turn your sake very, very sour. To get some shelf life out of your sake, the next step will have to be pasteurization.