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.
Tasting results:
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:
Possibly the first ever Bodai moto made outside of Japan!
Hi all. I have been brewing sake for a couple of seasons according to Will’s awesome directions and this year I am experimenting with milling rates and also trying both a yamahai moto and a bodai moto. The bodai moto was started last night. I will let the ferment go for as long as it wants and let you know the results.
Very nice. I can’t wait to see how the Bodai turns out for you.
I’ve been using Biofine Clear in my commercial beer brewing for los angeles ale works. We make casks and add it to our main batch. I decided I wanted to see how this finning agent worked with sake and stupidly, didn’t pull off a test. As soon as the Biofine hit the sake, the entire solution turned opaque gray. The finning did the exact opposite of what was intended. I’ve used speedy bentonite to try to clear it up, but it looks like it’s not working either. At this point, I’m looking at filtering.
Sort of a roundabout way of asking a question. Have you ever used biofine clear for sake? It’s silicone dioxide dissolved in water. I’m not sure what happened, but I’m itching to find a solution as I don’t want to dump my latest batch unless I have to. Did your sake ever lose it’s soapy flavor? Did it turn out to be the filters? I’m not sure if a 1 micron filter is fine enough to remove the biofine.
Cheers,
Kip
Kip,
I have not use Biofine clear. I don’t understand why you would get the result you have.
The soapy flavor did wane a bit but the sake remained very viscus. Interestingly, a friend who has a very good wine palate mentioned that it was very similar to chardonnay. I didn’t notice this before but once pointed out I found it quite striking an more palatable.
Thanks,
Will
I have some insights for you. The soapy flavor is a typical off flavor from yeast autolysis (yeast death). The yeasts contain a certain amount of fatty acids that begin to degrade and break down after the yeast cells die. Soap forms from the salts of the breakdown of these fatty acids. Therefore, what you are literally tasting is indeed soap. With such a long racking time waiting for the lees to fall, you’re letting the sake sit on dead yeast.
My suggestion for fixing this issue is using bentonite just before pasteurizing the batch and then cold crashing within five degrees F. of freezing. I would then be sure to rack off the lees and dead yeast within about two weeks from cold crashing.
Another option for filtering sake at home would be using canister filters instead of the paper disc filters. CO2 would be required just like in your setup there to push the sake through the filtration. You can buy the canisters at most hardware stores for water filtration and gang as many of them together as necessary. For example, the first one might be a 1 micron paper filter, the next might be a GAC carbon filter. The beautiful thing is, the’re designed to withstand a certain amount of pressure and the paper post filters work better the more clogged they get (albeit the flow slows down dramatically).
hi,
please can you tell me what for a filtering equipment do you buy, how much did it cost and if the plates are reusable and if you think it help, another question what gas did you use for pushing
thanks
Angel, Hi,
I got the filter plate from William’s Brewing along with the filters. I got the kegging system from Main Brew. However, you could get these from most any home-brew shop. The filter plate is about $50 with filters around $4 for a pair. William’s also carries a “pressure tank” for around $60 so that would be around $120 and the pressure tank is hand pumped air. The keg system was around $210 from Main Brew and uses CO2 for the gas. I will use it for beer as well or I would not have gone with the keg.
All in all to get good clear sake you will need to use smaller than the 7micron filter than I used. Also, there is a different taste and smell that may have come from the filtering and if it does not dissipate I will not be happy.