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During the Edo Period, natto—which had until then been largely made by farm families for their own consumption—became a commercial product. Following World War II, automation made mass production possible. Natto consumption then grew, spurred by factors such as a health-food boom. Today over 720 domestic natto makers produce the stuff in numerous variations from natto with toned-down aroma or glutinousness, to natto with flavorings such as kombu (kelp) or chopped pickled vegetables. Even candied natto and chocolate-covered natto have appeared.
Amid this flowering of variation, traditional makers have continued to do a brisk trade. One is the Sasanuma Goro Shoten in Mito, Ibaragi. In addition to making natto packaged in conventional polyethylene containers, the company also sells natto the old-fashioned way—bundled and fermented in rice-straw packets. A ball of natto is packaged in a small rice-straw sheet that gets rolled up like a blanket and tied shut with a piece of string at each end. One reason Mito is a nationally renowned natto-making area is the locality’s customary use of small soybeans. Compared to natto made with larger beans, many people find the smaller beans a better match with rice. The Sasanuma Goro Shoten was the first company to make small-bean natto and sell it at trains stations as a local souvenir.
Although bacillus natto bacteria thrive in rice-straw bundles, it is also easy for other organisms to develop, so when using this kind of natural production method, great care must be taken to prevent the growth of unwanted bacteria. There are many special techniques for preparing the straw bundle and wrapping the natto in it. Compared to the use of more modern containers, using straw bundles requires roughly three times more personnel and yields less than half the quantity. Why use straw bundles if they are so much more work? According to Sasanuma Goro Shoten President Takashi Sasanuma, natto just tastes so much better that way.
“The straw lets the natto breathe, which preserves both firmness and aroma of the beans,” says Sasanuma, “Even people who say they don’t like natto often change their minds once they’ve had natto that’s been fermented in fragrant rice-straw.”
To bring out the full culinary experience of natto, it is important that it be glutinous and stringy. This is achieved by stirring it well until the strings are white: bringing out the glutamine in the beans enhances the flavor. To get the maximum blood-clot prevention benefits of natto, it should be eaten in the evening, since the blood is more prone to clotting during sleep.
Although a peculiar food, natto is a quite health-promoting form of “slow food,” and is likely to remain a regular feature on Japanese dinner tables for long to come.
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a.The making of natto delivered in straw packets starts with the tying together of the straw. An appropriate amount of straw is gathered and tied together at the ends and in the middle, and a cradle is made to receive the boiled soybeans. The rice straw, which is sterilized before use, is collected from farmers contracted to grow it. |
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b.The soybeans are inserted into the cradle by specially built machines. A certain degree of practice is required to be able to catch the natto quickly and then ready the next straw packet. |
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c.The packet, now filled with beans, is placed on a conveyor belt that carries it to the next step. |
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d.The remaining part of the straw packet is folded inward to cover the natto and close the packet. |
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e.Finally, the closed packet is tied shut to complete the process. |
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f.The straw packets are loaded onto a wagon and moved to the fermenting room. Here they are allowed to rest for 20 hours at about 40°C, then cooled and made ready for shipment. |
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