OK, so the bodai moto based sake I am working on, rested for about 1 month after pressing. Normally, I would have racked it after a couple of weeks but the lees were just not dropping out. I have not had a sake that was so slow to drop its leas before. After one month the sake appeared as in the picture below:
Not very encouraging in turns of being able to recover a large percentage of the sake as clear sake. Anyway, I had been thinking about filtering sake and thought that this maybe a good batch to give it a try with. You may recall that the fermentation went very slow and I pressed it too early despite it having had more time to ferment than most. The moromi went through stages of smelling like green apples, strawberries and finally banana’s. These aromas have been very strong and are very evident the minute I open the cooler. At one month after pressing the banana aroma continues to be very strong; Ginjo-ka on steroids.
The equipment I used for filtering consists of a 5 gallon Cornelious keg, and a plate filter with a 7 micron filter paper. I also have 3 micron and 1 micron filter paper but I was afraid that the filter would clog and I would lose too much sake. As it turned out the filter was very close to being clogged if not actually clogged at the end of pushing about one gallon of sake with leas through it. The following picture shows the front and back sides of the 7 micron paper filter and the back plate of the filter housing.
The rough side of the paper filter is the side that contacts the sake. The grooves in the back plate are placed up against this rough side and act as the channels for the moromi to spread out over the entire filter area. With the rough side of each paper filter against the plates the moromi flows from the supply tube to the grooves to the filter leaving most of the leas while the sake passes through the filter into the middle of the housing where it exits to the bottle. The next picture shows the complete setup laid out.
Using this setup I pushed one of two jugs of sake through this system. The other I left for my usual racking. The next picture is that of the resulting filtered sake. Actually this picture was taken about half way through the process.
As you can see in the above picture, the filtering is not fine enough to make the sake all that clear.
When I opened the filter I can see just how thick the leas on the filter are and how the filter had started to crack and break across the edge of the fine side of the filter. This is the side facing into the middle of the filter housing. I had started pressing with 5 PSI and move up to about 10 PSI near the end of the filtering to overcome the back pressure of the clogged filter.
This was the first good chance to see how the sake, made with a bodai moto, is turning out. First the aroma was not very strong, especially in relation to the aroma that is coming out of the cooler. While not strong the filtered sake has an off putting aroma, kind of a soapy aroma. There is also a soapiness to the taste as well and it is pretty harsh. Needs more time to mellow.
In comparison, the other half of the sake that I simply racked (no filtering) does not have any soapy aroma or taste. It is much smoother with a much nicer mouth feel.
Both the filtered and unfiltered versions of this sake have a bit of a different taste than your average sake, whatever that may be. I have not decided if I like it yet but it is definitely not off putting or repulsive. I will let it age a little longer and try it again to see if the difference persists. I am wondering if the soapy aroma and taste has been added by the filter.
So a little more conditioning and then I will do some analysis on this sake as well as a final tasting. Till then…
P.S. The first post on this Bodai-moto based sake was: