Japanese sake brewing project (7) ~ The second batch

Different type of KOJI

The first batch is now aging stage, I probably need to rack it some time a few weeks from now.   It has not been clear yet.   In a mean while, I started the second batch with some adjustments.

Here is some points of the adjustments:

1. Different type of KOJI
2. Reduce the amount of KOJI
3. Reduce water

The first batch, a freeze-dry type KOJI was used.    There is another type of KOJI in a local Japanese grocery store.   It is still a "dry" KOJI, but the one in the photo above has more moisture.   Also, the amount of KOJI for the previous experiments could be too much.  It may impact to the color and flavor.   The second batch used only a little more than half of the previous batch.

Then the last one is the amount of water.  I reduced around 20%.

The starter process started last night and I observed bubbles from the air lock.   It seems to be much slower fermentation than the previous batches.

(To be continue)

Japanese sake brewing project (6) ~ Pressing / Pasteurization

Pasteurization -- deactivate fermentation and kill unexpected bacteria and etc.

Pressing

After the last addition (the third addition), the fermentation was active for more than 2 weeks.   A timing the fermentation to be stopped is one of key decision for brewing sake.   Many article on the internet mentioned, it would be around 2~4 weeks from the last addition.

In my first brewing, I decided to stop the fermentation after 17 days.

Pressing method

In my test brewing before this batch, it is very hard to press just using a close.  Therefore, I thought using a metal mesh would be a good idea to separate / extract the liquid part and sediment.  My fermentation tank has  "a down spout".   When I brew beer, using it to take beer out from the tank.  The contents will be separated with 3 layers after a several days of the fermentation.   The middle part is the liquid part and it is probably easy to extract the liquid part from the down spout.

Actually, it was a good idea.   The middle part is really liquid and not much sediment included.  Then we can minimize the pressing effort.   I extracted the middle layer from the spout and total amount of the liquid part is about 1.5 gallon.   Then the left over is pressed with a metal mesh.   However, the sediment is soft and if we press the sediment, then the sediment passed through the mesh.   With this process, I got about extra 1 gallon of liquid with a lot of sediment, it is called "Nigori" in Japanese.

Pasteurization

After pressing process, I did pasteurization that deactivates the fermentation and kill unexpected bacteria and etc. to store in the room temperature.   The process is put a jar that has the liquid part into a larger jar to heat up.   I put a thermometer to monitor the liquid temperature.   Based on the information on the internet, the temperature needs to be up to 60C+ (140F+).   Then chilling the liquid immediately.   After that, it will put in jars to store.    It will take a few weeks to settle the sediment into the bottom.

Tasting

 I tasted it after the process.   The taste was not too bad.  Actually, it is much better than I expected.  I still needs to wait more time for aging the sake.   However, I started considering how I will proceed the next batch.

(To be continue)