Tsukemono, which are pickles fermented in rice bran (Nukadoko), is the perfect companion to plain steamed rice. This is because of the refreshingly acidic taste and aroma that is produced when fermenting ingredients in rice bran (nukadoko) because the lactic acid and yeast grow in balance.
What is Tsukemono?
Tsukemono means a pickled thing in Japanese. It is said that Tsukemono is developed in colder regions for preserving and storing vegetables. There are many different ways of classifying tsukemono, however, they are typically classified by the condiments used to pickle, such as salt (shiozuke) miso (misozuke), soy sauce (shōyuzuke), rice vinegar (amazuzuke), rice bran (nukazuke), sake lees (sake kasuzuke) etc in Japanese cooking. Further, in addition to vegetables, seafood, and fruits are also be pickled in Japan.
What is Nukazuke?
Nukazuke, one of the staple fermented pickles, has been on Japanese tables and a magnificent nutritional food since there was no means of preservation such as a refrigerator. Nukazuke is mainly vegetables pickled in rice bran bed called “Nukadoko” made from mixing rice bran (nuka), salt and water. Vegetables have microorganisms such as lactic acid bacteria and yeast. Rice bran mixture (nukadoko) is a suitable environment for those microorganisms to ferment, which enhance the nutritional value of the vegetables. Reference
What’s in the Rice Bran Fermenting Bed (Nukadoko)?
Nukadoko consists of rice bran, salt, water, kelp and chili flake.
- Rice bran (Nuka) is the most important ingredient. The rice bran (nuka) is the exodermis of rice that is removed from brown rice when it is milled into white rice.
- Salt – the amount of salt is calculated at 10% – 12% of the rice bran weight.
- Water – The water needs to be boiled and cooled before added in order to remove the chlorine in the water.
- Kelp – will add umami to the pickling bed.
- Chilli flake – are added for antiseptic and antioxidants. Mustard powder is often added as well.
Other Optional Ingredients
The following ingredients are optional which add some flavour to the rice bran fermenting bed. Garlic, Japanese pepper (sanshō), yuzu, ginger, dried shiitake mushrooms, etc.
Suitable Containers for Nukadoko
In terms of materials, you can use a wooden container, pottery, enamel, plastic though, in my humble opinion, the enamel is the best because 1. It’s resistant to acid and salt. 2. Unlike plastic, the chemical substances never dissolve. You will need 12-15 cups volume container for 2lb(1kg) of rice bran. I use a rectangle enamel container(link).
How to Make Nukadoko?
It takes about 10 days to 2 weeks before Nukadoko is able to pickle vegetables and other foods. Prepare a container and gather all rice-bran pickling bed ingredients listed above. Then you need to gather vegetable scraps such as outer leaves of cabbages. This process is called “Sute zuke”. Turn the nukadoko once every day in winter and twice in summer with changing the vegetable scraps every 2-3 days. Continues doing so for about 2 weeks to let the fermenting rice bran bed mature.
Once it is ready to pickle anything, you need to store it in a place where the temperature is 68-77°F(20 – 25°C). I usually keep mine in refrigerator in summer as Brisbane, Australia is quite hot and in winter it is sitting on my kitchen bench. Basically, you need to stir upside down every day with your hand in order to promote fermentation, growing both the lactic acid bacteria and yeast in good balance.
Pickling Ingredients and Time for Tsukemono.
Most vegetables, fish and meat can be pickled though, I have never tried fish and meat myself. My absolute favourite is eggplant (aubergine) and cabbage. Vegetables like eggplant (aubergine) need to be rubbed with salt to keep the nice purple colour and also to remove astringent taste. The length of time needed to pickle ingredients in Nukadoko depends on the type of vegetables. This time is also indication only to as it is influenced by temperature, climate and other factors.
Cucumber is a Nukazuke classic ingredient. Cucumber has an astringent taste so you need to do a little bit of prep before it gets pickled in Nukadoko. Chop off both ends and rub with salt. This will draw the water out of the cucumber then you can pickle in Nukadoko. It will be pickled in 7-8 hours.
Carrot is quite a hard vegetable so if it is large, cut it in half or quarter in length width with skin intact. I used Dutch carrots which are small so I just washed it and chopped off the leaves and pickled as it is. Since it is a hard vegetable, it takes longer to get pickled. It takes about 1-2 days to pickle.
Wash and chop the leaves off. Then pickle for 1 day.
A: You can leave them in. Kombu kelp can be consumed after 2-3 days also.
A: It is caused by over fermented lactic acid bacteria. Add Japanese mustard powder 1tbsp and keep the container in cooler placer.
A: Add more roasted rice bran, but you need to be careful with salt percentage as well. So add 7% of the amount of rice bran you are adding.
A: Place kitchen paper over the rice bran floor and let the paper soak the excess water. Or pickle something dried food such as shiitake mushrooms.
A: The cause of the smell like cemedine is that the bacteria which dislike oxygen have over fermented. It probably is caused by the high temperature or insufficient turning the rice bran bed. You also could add some Japanese mustard powder.
A: The mold grows on the surface of the rice bran floor is film-forming yeast, which causes an unpleasant odor like an adhesive and spoils the taste and flavour of tsukemono. There are four reasons.
1. Not turning around the rice bran bed enough. Turn the rice bran mixture more often and well.
2. The salt percentage is low so add about 1 tsp of salt.
3. Left the container in a place where the temperature is more than 77°F(25°C) … leave it in the fridge.
4. The rice bran bed is too moist. Let a kitchen paper soak the moisture.
A: Add roasted rice bran, 10% salt of the amount of the rice bran you are going to add, and 4 cups of water.
A: You can substitute with wheat bran.
Other Japanese Tsukemono Related Recipes
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Recipe Measurement Notes
Tsukemono-Nukazuke rice bran pickle
- 800 ml Water
- 800 g Roasted Rice Bran
- 80 g salt
- 250 g matured rice bran mixture Optional *1
- 2 inch Kelp (5cm)
- 1 dried chili
- 6-8 outer leaves cabbage for maturing the rice bran bed
- Boil the water in order to remove chlorine and set aside to cool down.
- Place the roasted rice bran into the container that is used for pickle
- Add salt to the roasted rice bran and mix them well
- Pour the cooled down water into the container and mix them well with hands
- Press the konbu kelp, chili and garlic in and bury completely in the rice bran bed.
- Make the top surface flat with your hands, wipe the container to clean (avoiding other bacteria growth) and place a lid on.
- Refrigerate to rest overnight.
- Next morning, take the container out of the fridge and press the cabbage leaves into the rice bran pickling bed (nukadoko) and bury them completely with rice bran.
- Wipe the inside of the container with wet cloths to clean.
- Place the lid and leave it overnight at room temperature. *5
- Next day, remove the cabbage leaves out of the rice bran bed, and stir the rice bran bed well.
- Add another cabbage leaf, cover with the rice bran, flatten the top surface and wipe off to clean the container with wet cloths.
- Repeat the above process 3-4 times in order to mature the rice bran pickling bed. *2
- After you repeat the above process 3-4 times, the rice bran bed is ready to pickle.
- Wash the vegetables that you want to pickle and prep the vegetables. *3