Nukazuke: Japanese Rice Bran Pickles

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Having corralled some of San Francisco’s wild yeast and soured my own crock of sauerkraut, it was time to move on to my next live food project: nukazuke. I was still a new convert to the Church of Fermentation, but a recent trip to Japantown helped immerse me completely.

I was pushing my cart around the back corner of Nijiya Market and came across bags of flaky rice bran, or nuka, the brown coating removed from rice grains during the milling process. Hmmmmm….now what could I do with those? Fortunately, not knowing how to use an ingredient has never stopped me from tossing it into my shopping cart. Browsing my Japanese cookbooks later, I found references to rice bran pickles. My go-to expert on Japanese pickles, Ikuko Hisamatsu, provided a basic recipe for traditional nukazuke in her book Quick & Easy Tsukemono.

As it turns out, “quick” and “easy” are relative terms. Homemade nukazuke are most definitely not for anyone who thinks food should be fast or convenient. But if you make your own vinegar, tend a few chickens in your backyard or brew beer, then these pickles will not phase you at all. If you’re dedicated to eating well and to providing your gut with a healthful balance of good bacteria, these pickles will be worth your time, I promise. And if you obsess about the proper method of boiling soba noodles or have perfected both chawanmushi and tamagoyaki, then consider nukazuke as serious leveling up.

For those wanting to take a half step, look for instant nukazuke kits in Japanese grocery stores: small plastic containers with the rice bran bed mixed and inoculated already for you.

Hard-core picklers, though, keep reading.

Nukazuke are one of the most rewarding foods I’ve ever made. I love their complex yet subtle sour-saltiness and their extra crunchiness. My husband and I enjoy small bites of them at simple, homey meals. A Japanese meal might end with a single bowl of steamed rice accompanied by a beautiful dish of nukazuke. A handful of radishes plucked from the rice bran makes a much healthier snack than potato chips, and they’re much more delicious, I think. It’s the perfect project for spring and early summer, as vegetables return to market in all their freshness and abundance.

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Nukazuke pickles — slices of cucumber, eggplant and baby daikon — add zip to a summer lunch of Korean-style salad nicoise (with bulgolgi-flavored tuna carried back from LA), pan-seared shishito chiles and miso soup with baby bok choy.

Dependable, Hard-Working, Likes Regular Attention

Like some of the better things in life, these pickles are a long-term commitment. After inoculating the bed of rice bran, known as nuka-doko, with the proper microbes, you’ll need to wait another three or four weeks before the best flavor develops. And from the first day you mix the pickling bed, you’ll need to aerate the rice bran every day by hand.

Yes, every day. By hand.

The good microbes happen to live on your hands, and they thrive with a good supply of air. The undesirable bacteria are anaerobic, so daily stirring keeps them in check. (There’s a way to leave the rice bran in deep hibernation for a period of time, used back when the winter season cut off supplies of fresh produce, but it’s not a fix to be applied too often.)

The daily stirring takes about 30 seconds, so no big deal if you’re in the kitchen anyway. In return for helping them breathe, the lactobacilli that have colonized your rice bran bed will happily transform fresh vegetables into crisp, flavorful, healthful pickles. The most delicate require only two hours, while large and dense vegetables may need to be buried for a few days. Some daikon roots are aged in the rice bran for years to develop intensely deep flavors.

Last summer, John “Taikoman” Ko had connected me with Hideaki and Hitomi, two dedicated and talented cooks in Sebastapol. From Hitomi I received a few tips on starting my nuka-doko. She gave me an inspiring pep talk about how good the pickles are, how much her son loves them and how many years she’s successfully tended her rice bran bed. She even travels with her nuka-doko to make sure it receives the attention it requires — on hot days, she stirs it twice — and then makes pickles for her hosts.

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Apple peels drying in the sun. They’ll lend sweetness to the rice bran bed.

To make my own nuka-doko, I adapted Hisamatsu’s formula in her book (15% salt, by weight of the rice bran) and incorporated some of Hitomi’s suggestions. The rice bran, salt and water are the three essential ingredients. In my own rice bran bed, bread speeds up the inoculation process, seaweed adds umami, apple peel lends a hint of sweetness, chiles keep away bugs and worms, eggshells clarify while contributing calcium and ginger adds its own bright flavor to the pickles.

Preparing the Rice Bran Bed

The nuka-doko serves as a medium for the microbes, a carrier for the flavorings and a gentle cushion in which the vegetables rest. Buried for two hours or two days, they emerge from their sleep brighter in color and flavor. Like vinegar and sourdough, receiving a small amount of active starter bacteria from a friend’s established colony will give you a jump start, but inoculating your own nuka bed is still pretty straightforward.

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Toast the rice bran in a wide, heavy pan until it has deepened a couple of shades in color. Frequent stirring, especially as the bran browns, prevents scorching.

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I use a plastic bag and a rolling pin to crush the eggshells.

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Moistened bread helps attract and feed the desirable, healthful microbes to the rice bran. Ginger is one of my favorite flavors, so I add a few pieces to the bread before pureeing it with water.

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While the aromatics are optional, konbu seaweed gives nukazuke that undefinable depth of flavor that makes Japanese cuisine both subtle and satisfying.

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The carbo-rich bread slushee and additional cold water are stirred into the rice bran with clean hands to ensure inoculation with good germs.

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A deep Cambro container becomes my starter crock. (The lovely, traditional wooden buckets in Japantown, priced at nearly $300, will have to wait.) Later, after the rice bran is well inoculated, I’ll transfer it to a ceramic pickling crock. For now, though, a few wedges of cabbage serve as my starter vegetables in the clear container. A thin, clean kitchen towel serves as the cover for the bed. The rice-bran bed is a living organism — a complex colony, in fact — that needs to breathe, so good air flow is critical.

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After two days in the nuka-doko, the cabbage has wilted and become salty. The wedges aren’t properly fermented, this being only the first week of the rice bran bed, but there’s a wonderful crunch to the leaves and just a hint of the nukazuke’s distinctive woodsy flavors. I could throw them out…

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…or I could coat them with a heady mix of chile oil, minced garlic, grated ginger, sugar and rice vinegar to balance the salt. These end up as a host gift to Joshua and Jineui on the occasion of Olivia’s welcoming party.

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My current favorite nukazuke are radishes. Above are some little cuties right after I pulled them from the fully fermented rice bran bed, about five weeks after I first mixed it all together.

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And here are the radishes, rinsed and ready for munching. I eat them out of hand, stubby stem and pointy roots and all. Nukazuke are instantly recognizable by their heightened colors, with jewel-tone brightness, an elegant shimmer on the outside and a delicate translucence inside.

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For extra crunch, I dried daikon for a few days at our hottest window before burying the whole root in the rice bran. (The cubes on the right were treated to a classic Vietnamese pickling brine made of fish sauce, caramelized sugar and lots of garlic.)

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This is the first nukazuke I made away from home. The rice bran bed traveled with me to Los Angeles for a weeklong stay at Juli’s place in West Hollywood. These Brussels sprouts went straight from the Santa Monica farmers’ market to the rice bran bed, then emerged three days later as very yummy pickles. Remember to cut little cross-hatches into the stems to encourage even distribution of the rice bran’s fermenting friends.

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Once my rice bran bed became home to a well-established, bustling colony of lactobacilli, the Brussels sprouts take only one night to pickle. They’re put to bed just before I go to sleep myself; they’re ready in the morning. If I wanted to pickle them in a few hours, I just cut each sprout in half.

Other vegetables you can bury in your nuka-doko: baby eggplants, carrot sticks, bell pepper wedges, broccoli, cauliflower, cubes of pumpkin and other winter squash, young ginger and small, tender turnips. Some recommend rubbing the vegetables with salt before placing them in the rice bran, but I now skip this step and haven’t noticed any differences in flavor or texture.

Taking Care of Your Nuka-Doko

Wash your hands and dry them well before stirring the rice bran, removing pickles and burying new vegetables. Some people like to wear gloves or use a spoon, but the bacteria level will remain most friendly and flavorful if there’s repeated contact with your hands. Even if you don’t do it every day, do try to give your pickle bed some love now and then with direct contact.

Occasionally, you’ll need to stir in additional rice bran and small amounts of salt, as you’re removing a bit of the bed every time you take out pickles. Add aromatic ingredients according to your own taste preferences. Try mustard powder or whole garlic cloves (which can be sliced and eaten as a pickle later).

Don’t leave your vegetables in the rice bran bed too long, as they’ll turn it sour. The moisture level will vary week to week, depending on the type of vegetables you’re pickling. If you notice too much moisture, pooling at the surface or at the bottom of the container, then soak up the excess water with wadded paper towels.

If you miss stirring the rice bran for a few days, you might see a white mold growing on the surface. Simply skim it off, transfer the rice bran to a clean container and add salt. With regular aeration, the good microbes will regain their hold in a few days.

For deep storage, remove all vegetables from the rice bran. Cover its surface completely with a 1/2-inch layer of mustard powder, then a 1/4-inch layer of salt. The top should be completely white. Drape the container with several layers of thick towels, to allow a small but steady amount of air flow, and then store the container in a cool, dark place. When you remove it a few weeks or months later, scrape off the mustard and salt layers. Restart the rice bran bed with test vegetables just as you did when you first inoculated it.

NUKA-DOKO RECIPE

To hold the nukazuke for a few days after they’re fermented, remove them when they’re ready and store them in a covered container in the refrigerator. I like to leave a thin layer of the rice bran on the vegetables to keep them flavorful and “fresh” (i.e. alive), rinsing them just before serving. Once rinsed, they’re best eaten within an hour or two.

5 ounces (142 g) sea salt
32 ounces (910 g) organic rice bran
5 x 5-inch square of dried konbu, soaked in cold water overnight and torn into thin strips
Peel from 2 apple, pears or Fuyu persimmons, removed in wide strips and dried
Shell from 3 eggs, crushed into small pieces
1/4 cup sliced dried Korean chiles, or dried chile flakes
2 inches ginger, minced
2 slices bread, pureed with 2 cups cold water (preferably filtered to be free of chlorine)
Assorted starter vegetables such as radishes, carrots, cabbage wedges or small cucumbers, rinsed and dried

1. Combine the salt with 4 cups water in a small pan and stir over medium heat until completely dissolved. Set aside to cool.

2. Toast the rice bran over medium low heat until lightly toasted and fragrant. Let cool until you can touch the bran comfortably.

3. Stir in the konbu, apple peel, chiles, ginger, bread puree and cooled salt water, using your hands and squeezing with your fingers to distribute all the ingredients evenly. The consistency should resemble wet sand. Drizzle in more cold water, if needed.

4. Transfer the mixture to a deep ceramic, glass or plastic container. Leave empty space in your container to allow room for stirring the rice bran. Bury your starter vegetables completely in the rice bran bed, and press down all over the surface to compact the rice bran well. If desired, place a wooden drop lid or a saucer right on the surface of the rice bran bed, but be sure to leave about an inch open between the rim and the side of the pickle container to allow air flow. More importantly, drape  the container with a clean cloth and place in a cool location that’s within relatively easy reach of your daily routine.

5. The next day, stir the rice bran bed, scooping and turning it with your hands to aerate it well. The starter vegetables can be left for two to three days before being replaced with new ones. They will be overly salty and not yet properly pickled. Continue using starter vegetables for about two weeks, until the bran bed has absorbed extra moisture and developed an earthy, woodsy smell. Regularly taste the starter batches to learn how your nuka bed changes as it ferments.

6. After two weeks, taste vegetables after pickling one night. Eventually, once your nuka bed is mature, you’ll be able to pickle small or cut vegetables in 2 to 4 hours, larger vegetables in 6 hours or overnight.

7. Give your nuka-doko regular attention and enjoy the products of its quiet work.

[Please note: I didn't receive notices about new comments for a crazy long period of time. Poor little me, I thought no one was reading my pickle blog. As it turns out, there was a "server misconfiguration" that created an embarrassing backlog of questions and comments. I ended up e-mailing folks directly with my responses in addition to posting here. Many apologies to everyone and many, many thanks for your patience. It's all fixed now, so feel free to ask away again!]

100 Responses to “Nukazuke: Japanese Rice Bran Pickles”

  1. Becci says:

    Hi, what a great blog, thanks :) I really want to try making nukazuke, but after searching all the asian supermarkets in my town I can’t find rice bran anywhere. I can get “fine” rice bran from an online organic shop, but they’re advertising it as a breakfast cereal and its crazy expensive, so I’m not sure if its the right sort of product. I see from some other comments that people have successfully substituted wheat bran, which is cheap and easy to find. Any tips for using wheat bran? Should I adjust the recipe at all? Thanks!

    • Thy Tran says:

      Hi Becci,

      I think wheat bran should work fine. Japanese people used rice bran because that’s what was easy and abundant for them. I haven’t used it — have been very tempted to try it, but one pickle bed is enough for me for now — and am definitely interested in your own experience with it. Let us know how it goes!

  2. Vida says:

    Hi Thy,

    Just started my Nuka bed last night. I added apple peels but didn’t dry them and I didn’t wait for the water to completely cool after I boiled it with the salt to dissolve. I made a slurry of ginger, garlic and a seeded red pepper and mixed it in with the toasted rice bran. I then added beer and slowly mixed in the warm salted water that also had strips of Kombu. It felt possibly a little too wet so I mixed in dried shiitakes. Then I mixed in a peel from one carrot. This morning I hand turned it. The mixture is in a plastic container. I covered it loosely with the lid without snapping it shut so it wasn’t air tight. Am I on the right track? Can I keep hand turning the bed for a couple of days before I add more veggies? I’m excited for my first batch of pickles but worried that I might already be doing something wrong. Would appreciate your expert opinion and suggestions. :)

    • Thy Tran says:

      Vida — Congrats on embarking on your own nuka adventure! It’s really too soon to tell about your pickle bed, as it’ll take up to a month for it to develop fully. Water that’s too hot can kill the microbes that you’re looking for, so it may take a little longer for them to return. In the meantime, do keep an eye on it, continue burying and retrieving vegetables, and enjoy the discovery of their changing flavors and textures as the rice bran matures. If you live in a hot area, be sure to skim off any white molds that might grow on the surface and then try to soak up the excess moisture. Otherwise, it’s just a matter of time and patience now….Have fun!

  3. Carla says:

    I have been reading how to make nukazuke and have assembled various incredients. I now have nuka, ground up egg shells, kombu, daikon, burdock, carrots ready to go.
    What is holding me back is figuring the percentage of salt to use. Can you please clarify that? I am finding this a bit more complicated than I anticipated. Also, just how open should the container be? I have a porcelain container that is large enough to lay things down. The lid sits on top, and has a small vent hole on top.

    • Thy Tran says:

      Carla, Sorry about the delay in getting back to you…busy time of the year with the harvest season! The percentage of salt can range between 5% to 25% — by weight — of the bran. You don’t need to worry about being super precise. The higher end is really rather too salty for me, while the lower end means you need to be more vigilant with stirring, especially in warm climes, to keep non-pickling microbes at bay. For first-timers, I recommend %15 percent. You’ll be tossing in additional salt and bran later, so at a certain point, you really won’t know the actual number. Just keep your eyes open to what’s going on in the crock, adding salt if you find mold growing quickly at the surface. This will be an issue especially if you’ve incorporated fruit peels into your bran bed. Your own tastebuds (esp. salt tolerance) will determine the higher limit. For an easy, thumbnail reference to salt weight: 1/4 cup of kosher salt is about 1.5 ounces (depending on the brand). Let me know if you have any other questions. Good luck!

  4. Carla says:

    Fabulous blog, I have searched the Net for information on how to set up a nukadoko, and you have the best information I’ve found so far. I started my nukadoko yesterday, and am now waiting and mixing by hand. So far I’ve had to change my containers a couple of times as the first two were not large enough. Now I’m using a small earthen ware crock. Ive found being able to get my hands in nicely to mix things, and clean the sides of the container serious consideration.
    I guess it’s just mix and wait. Thank you for all your help.

    • Thy Tran says:

      Carla — Thanks for the extra tip and reminding me of a very good point! I also went through a couple of different containers until I found one with just the right height (a little extra clearance for stirring without getting the bran all over the counter) and the right width (to arrange and retrieve larger pieces more easily). And, to be honest, one that was on the more attractive end of the spectrum so that I could leave it proudly on my counter, where I’d remember to take care of it. Mine is an old cylindrical pickle crock, with a pretty printed napkin draped over it. Easy.

      Hope you’ve been enjoying your pickles!

  5. Mitch says:

    I just started a Nuka bed a few days ago as well! I had a question…is the bed supposed to be in the fridge or left out? If left out, where is a good place to put it? Thanks!

    • Thy Tran says:

      Mitch — Leave it out, preferably in a place that you will see everyday. It’s easy to forget, especially in this early phase, and if you live in a hot climate, it’s that much more important to be regularly stirring it. If you need to slow down the fermentation — during vacation, e.g. — then cover with an opaque layer of salt and put it into the fridge so the microbes will go into hibernation until you get back and return your bed to room temp. Have fun!!

  6. Ruby says:

    Hello I have just made my first nuka batch since I lived in the macrobiotic community 30 years ago. It smells alcoholic, not the smell I remember. Is it spoiled or is there some way to deepen the flavor? Will I get an answer in my email or will I need to bookmark and check this page? Guess I’ll find out!
    Thanks,
    Ruby

    • Thy Tran says:

      Ruby, I’ve never experienced the alcoholic smell, but it sounds like you have more ethanol fermentation happening rather than acidic or mixed acidic fermentation. Do you have a large amount of simple sugery or high-carbohydrate ingredients in the bed? Or perhaps you need to change how often you stir your bed or how much you stir each time? It’s a very complex blend of microbes, and they are pretty adaptable, so you’ll just want to spend some extra time adjusting until you increase and strengthen the yeasts that will contribute more lactic acid. I’m actually on vacation right now, but here’s one good link that discusses some of the differences in fermentation in food. http://www.fao.org/docrep/x0560e/x0560e10.htm

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