Getting to know natto, a sticky, stinky, superfood rich in probiotics.
It’s sticky and ... fragrant. Natto is a traditional Japanese food made from fermented soybeans. It’s rich in probiotics and vitamin K—which is especially important for vegetarians and vegans—and has health benefits such as improving bone health and blood circulation.
In their new book, Miso, Tempeh, Natto & Other Tasty Ferments, fermentation experts Kirsten and Christopher Shockey take us into a new realm of probiotic superfoods. The couple has been fermenting foods for 20 years and teach fermentation skills at workshops all around the world. In this book, they expand beyond the basic components of traditionally Asian protein-rich fermented foods, coming up with creative ideas like ancient grains tempeh and heirloom cranberry bean miso.
They also share details on natto, which, while popular in Japan, isn't commonly seen in the U.S. We asked if they would share a basic recipe from their book to get us started learning more about natto. Thank you, Kirsten and Christopher!
Yield: 4–5 cups
This is a basic recipe for classic natto. There isn’t a whole lot of space for creativity. As we developed a taste for the biofilm, we discovered that if you use a little more water when inoculating the beans, you will end up with a little more biofilm in your natto.
Process natto (see step 1)
Fermentation 20 hours (30 hours for a more pungent natto)
2½ cups (450 g) soybeans, preferably the small natto-style beans
Natto starter (B. subtilis var. natto; see note below)
Boiling water, for warming the containers and inoculation
Note: Use the quantity of natto starter specified by the manufacturer of your starter. It’s usually in the range of ⅛ to ½ teaspoon (the variation stems from whether the starter is pure spores or spores dispersed in rice flour).
1. Steam the soybeans for 9 hours if cooking on the stovetop, or for 45 minutes on high pressure if using an electric pressure cooker. When the beans are almost ready, bring a kettle of water to a boil. Once the beans are ready, quick-release the pressure, if you used an electric pressure cooker. If you steamed them in a pot, turn off the heat, but keep the lid on the beans until you are ready to go. You will want to work quickly since the natto spores are activated by a heat shock.
2. Pour a bit of boiling water into a bowl and a shallow glass or stainless-steel casserole dish to sanitize and warm them; let sit for 30 seconds and then pour the water out into your sink. Pour ¼ to ½ cup of boiling water into the bowl, then add the starter culture and mix thoroughly. Add the hot soybeans to the starter culture and mix carefully.
3. Transfer the beans to the casserole dish and spread in a thin layer, preferably about ½ to 1 inch deep, and no thicker than 2 inches.
4. Place a sheet of aluminum foil or plastic wrap across the top of the casserole dish, crimping the edges to seal tightly. While holding the aluminum foil or plastic wrap taut so that it doesn’t crush the beans, poke a series of air holes across the top, about 1½ inches apart in a grid pattern. If you’re using plastic wrap, then lay it directly on the beans.
5. Place the natto in a relatively humid incubation chamber (see page 114) at 99°F/37°C to 113°F/45°C; we have had the best results at 106°F/41°C. Incubate for 20 hours, or until you smell a nutty, alkaline aroma and you see a white film across the top of the beans. Run a spoon across the top of the beans. The spoon should stick slightly, and threads should form behind it.
6. Place the natto in a sealed container and refrigerate. Ideally, let it age for 1 week for deeper flavor. It will keep in the refrigerator for 4 to 5 weeks.
Excerpted from Miso, Tempeh, Natto & Other Tasty Ferments by © Kirsten and Christopher Shockey. Photography by © Dina Avila. Used with permission from Storey Publishing.