June 24, 2011

Final Notes (for Now) on Nukadoko and Nukazuke/ぬか床とぬか漬けに関する(今のところ)最後の注意点

Nukadoko requires daily maintenance. More specifically,

1. You must mix your nukadoko once a day in the winter (room temperature < 15C) and twice a day in other seasons.
2. You must keep your nukadoko in a temperature range of 20-25C. If the room temperature is above 25C, consider putting the nukadoko in the vegetable compartment of the refrigerator.
3. Keep your nukadoko at a salt concentration of around 7%, and keep it slightly less moist than miso. To do so, remove any excess water from your nukadoko, and replenish your nukadoko with nuka (rice bran) with 7% salt (for example, 100 g nuka plus 7 g salt) when necessary.
4. If you cannot take care of your nukadoko for a few days, put it in the refrigerator (< 5C).
5. If you want to stop nuka zuke (rice bran pickling) for a long time, say, one or two months, put your nukadoko in the freezer.

1. 冬(室温<15度)では一日に一回、他の季節では一日に二回、ぬか床をかき混ぜる。
2. ぬか床は20~25度の範囲に保つ必要があります。室温が25度以上であれば、冷蔵庫の野菜室にぬか床を入れることを考慮して下さい。
3. ぬか床は塩分濃度を7%程度に保ち、また味噌より少し水分が少ない程度に保つ必要があります。そのためには、ぬか床から余分な水分を除去し、必要に応じて、7%の塩を含むぬか(100 gのぬか+7 gの塩)をぬか床に補充してください。
4. ぬか床を数日間、世話できない場合は、冷蔵庫(5度以下)に入れてください。
5. ぬか漬けを長期間(例えば、1~2ヶ月)中止したい場合は、冷凍庫に入れて下さい。

This morning, when I opened the lid, I immediately noticed paint thinner smell. I was a little upset, and checked the temperature of my nukadoko. It was 27C. I mixed it thoroughly, and put it in the vegetable compartment. At around 2 in the afternoon, I checked the nukadoko, and was relieved to find that the paint thinner smell was gone.

My nukadoko on June 23, after I took it out of the fridge:

I hadn't expected that the nukadoko could get smelly so quickly. Last night, I checked the temperature, and it was 25C, and I thought it was in good condition.



Sissi said...

Hiroyuki, thank you for all the posts about your experience with nukadoko and nukazuke. I have just tasted today my first pickled half-cucumber (I was worried i would spoil everything, so I put just half of it). It is really good, very delicate taste, it changed cokour like the Russian/Polish cucumbers pickled in salted water. It is slightly bitter too. I will try to leave it next time for 24 hours at least and will roll it in more salt.
I am constantly worried about the bran smell... Since I have never seen it nor tasted the pickles, I am not sure if it's correct. It smells a bit like nuts with a hint of...sake! Is it possible?
Should I take out the konbu and the hot peppers? (I have left them since I wasn't sure).

Hiroyuki said...

Sissi: I will answer only one of your questions for now. It's 23:30 here in Japan. I will answer the rest tomorrow.

Only one site explicitly says to remove the kombu from the nukadoko after the nukadoko is fully fermented but leave the red peppers in the nukadoko.

Sissi said...

Thank you Hiroyuki. Sometimes I don't realise what time difference there is between us... It's not very urgent!

Hiroyuki said...

Sissi: I have bookmarked more than 15 sites on nukazuke for reference. The following is my personal comments based on these sites, as well as my experience:

1. If the cucumbers themselves are bitter, do itazuri or rub with salt properly.
Over-fermentation may cause bitter components to be produced. Possible causes of over-fermentation include low salt concentration, insufficient mixing, and high storage temperature. To stop over-fermentation, add some salt and/or karashi (Japanese mustard powder), mix thoroughly, and store the nukadoko in a cool place or in the fridge for a while, with no vegetables in it.
You may have to discard much of your nukadoko and add additional nuka, salt, and water.
2. I suppose you describe your nuka as nutty because you roasted it properly. Some describe the fermentation smell as miso or sake smell. But if your nukadoko smells of alcohol, it is a bad sign because it means alcoholic fermentation is occurring (by yeast) due to the lack of oxygen.
If this is the case, mix your nukadoko thoroughly and store in a cook place or in the fridge. Low salt concentration may also cause alcoholic fermentation; you may want to add some salt to your nukadoko.
3. Leave the red peppers in the nukadoko, and add additional ones if necessary. Remove the kombu in 5-10 days, when you think you have extrated all umami components from it. You can have the pickled kombu. (I inavertently threw it away with cabbage leaves!)

Hiroyuki said...

And, if you use an air-tight container and store it at room temperature, avoid placing the lid tightly; leave some space so that air can enter the container.

Sissi said...

Hiroyuki, thank you for these precious points. My lid is tightly sealed and maybe the sake smell means there is not enough salt.
I shall add some salt today and keep the lid slightly open... and will taste the pickled konbu soon! I will put another cucumber today.
Thank you so much!

Sissi said...

I have just tasted the pickled konbu! It's amazingly good! I will maybe have it in a salad with fresh cucumber... Incredible!
I have added some salt, mixed the bran and I think unfortunately there is no more nutty smell... and no more sake smell. I hop the smell is not the paint thinner-like. Difficult to say.
Thank you once more!

Hiroyuki said...

Sissi: You have done it already??

It's hard for me to describe the smell of nukadoko, too. I think the initial nutty smell will be gone by the time the nukadoko is fully fermented. Anyway, your nukadoko will be good as long as it doesn't smell of garbage.

Sissi said...

It doesn't smell of garbage yet. The temperature is not very high in the kitchen, so I hope everything will be ok.
I will put a cucumber today to see how adding the salt changed the nukadoko.