Traditional pickled foods have become increasingly popular, with their palate-pleasing spicy, sour, sweet and salty flavors and varied textures that provide health benefits as well as serving as a digestive aid.
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The most popular traditional pickled foods in America are dill pickles, sauerkraut and kimchi — all of which share one thing in common: They are vegetables pickled in a brine, vinegar or other solutions and then left to ferment, a process called lacto-fermentation. Just the sound of the words make our stomachs feel better.
How does lacto-fermentation work? During fermentation, a beneficial bacteria called Lactobacillus, which is present on the surface of all vegetables and fruits, begins to metabolize its sugars into lactic acid; this is a natural preservative that inhibits the growth of harmful bacteria.
Eating pickled foods in moderation keeps your gut flora healthy and supports immune function by providing an increase in B vitamins, omega-3 fatty acids, digestive enzymes and other immune chemicals that fight off harmful bacteria.
Pickling: A universal practice
The universe of lacto-fermented foods includes so much more than dill pickles, sauerkraut and kimchi. Since ancient times, people around the world have used this method to preserve vegetables and fruits when refrigeration was not available, and the tradition of pickling has carried on.
The Japanese have a diverse variety of pickles that use solid rather than liquid pickling mediums as such miso, sake lees and rice bran — all of which undergo the process of lacto-fermentation. The result is a distinctly tangy, crunchy and delicious assortment of pickles.
I am particularly fond of the nutty aroma and mild flavor of nukazuke, a traditional Japanese pickling method using fermented rice bran. Like wheat bran, rice bran is the outer layer of the grain that is removed during the milling process. In the U.S., most of the bran gets sold off to produce cattle feed and dog food, but the Japanese use it to pickle any type of firm vegetable, including carrots, cucumbers, cabbage, radish, zucchini, kabocha and burdock. The vegetables are buried in nukadoko, the fermented medium, to pickle for just a couple hours or overnight and reused again. The flavor of nukazuke is not as sour or spicy as kimchi or sauerkraut, but the health benefits are just as high.
How to maintain the nukadoko medium
Maintaining a nukadoko medium involves one crucial task: keeping it alive. You must stir the medium with your hands once a day to aerate it, so the bacteria can breathe and do their thing. It takes no more than a minute of your time, so you can incorporate it into your daily ritual.
Nukadoko also loves the good bacteria that live on your hands, so don’t use a wooden spoon. You will notice the medium has a distinct sour smell, which indicates the bacteria are actively working. I find the smell rather pleasant.
I keep my nukadoko in the pantry, which makes the daily stirring an easy task, but some people prefer to keep it in the garage. When choosing a spot to keep it, be sure it’s a cool place. If you don’t have one, you can keep it in the refrigerator, but the fermentation process will be much slower.
Every family has its own version of nukadoko. In the old days, one of the heirloom gifts a Japanese mother passed onto her daughter as a wedding gift was nukadoko, and it was not uncommon to find a nukadoko that was more than 50 years old.
Sad to say, this custom is disappearing in Japan and convenient foods are taking over. However, a slow movement is underway to restore traditional foods like nukazuke, including here in America. I have third- and fourth-generation Japanese-Americans who come to my pickling workshops to learn how to make their grandmothers’ nukazuke.
Sourcing rice bran in the U.S. is an easier task than I thought, because rice is grown widely in California. You can buy stabilized bran (commonly pasteurized) at Japanese markets or online, or ask your local rice farmer if they have some to sell. I contacted my friend Robin Koda at Koda Farms in South Dos Palos, one of the oldest rice farms in California, and she was happy to supply me with her raw bran, knowing its intended purpose.
One of my students commented that making nuka pickles is a bit like making compost, and it’s true. You will need a clay jar, an enameled pot or glass bin with a lid. I have an enameled pickling jar that’s about 30 years old, and it still works perfectly. The nukadoko medium has a texture similar to a wet sand or soft miso paste. Preparation of nukadoko takes about a week. If you have any leftover rice bran, keep it in the refrigerator or freezer because it is highly perishable.
Making nukadoko may seem a little tedious and time-consuming, but once you have been trained in the medium, you can keep it for years and pass it on to friends and loved ones. That’s what I enjoy doing.
Nuka Pickle Medium (Nukadoko) and Nuka Pickles
2 1/2 pounds of rice bran (nuka)
6 ounces sea salt
7 1/2 cups of filtered water
1 (6-inch) piece of konbu, cut up into small pieces
4 to 5 Japanese red chili peppers, seeded
Discarded ends and peels of vegetables (such as cabbage, carrots, cucumbers and daikon radish, but not onions)
2 garlic cloves, peeled (optional)
For making the nukadoko:
1. Place the rice bran in a heavy cast-iron pan and toast it over low heat. Use a wooden spoon or spatula to stir the bran so it doesn’t burn. The toasting process takes about 10 minutes. Once done, remove from heat and let stand.
2. In a separate large pot, combine the salt and water and bring to a simmer. Mix to dissolve the salt to make a brine. Remove from heat.
3. Slowly add the brine to the rice bran and mix it with a paddle until it reaches a consistency comparable to slightly moist sand.
5. Add konbu, chili peppers and garlic (if using) to the mixture.
For training the nukadoko and pickling:
1. Start by putting various vegetables scraps (try cabbage leaves, eggplant, celery and carrots) in the rice bran bed for about three days to allow them to lightly ferment. Take them out and discard them.
2. Repeat this three or four times, then you are ready to start pickling.
3. The nukadoko will develop a unique aroma and look like wet sand. At this point, a fermenting culture has been established and the nukadoko is alive and contains active organisms such as yeast and lactobacilli. You can now start putting vegetables into the nukadoko for fermenting. To speed the pickling process, you can rub a little salt on whole or large chunks of vegetables such as cucumber and carrots before you put them into the nukadoko. If the nukadoko becomes too wet, just add a little bit of rice bran with salt or a piece of day-old bread. Again, place fresh vegetables into the base for 1 to 2 days. Cucumbers may take only 2 to 3 hours on a warm day and 4 to 6 hours on a cold day.
Tips for maintaining the nukadoko base:
You will need to mix the nukadoko base once a day, turning it with your hand. If it the base feels dry, pour in a little beer. (Flat beer will work fine.)
If your most recent batch of pickles tastes too sour, add fresh nuka and salt (5 parts nuka to 1 part sea salt).
If you are traveling, you should move the nukadoko base to the refrigerator. The bacteria will go dormant, but you can reactivate them by giving the base a stir and leaving it out at room temperature. If you see any mold build up, simply scrape it off and add some fresh nuka to the mix.
Main photo: Nukazuke, or pickled vegetables. Credit: Copyright 2015 Sonoko Sakai