How Long Have People Been Eating Natto?
How Long Have People Been Eating Natto?

Natto and Climate

Regions where natto culture exists have a temperate climate, and most of the land area is covered in evergreen broadleaf forests. These temperate evergreen broadleaf trees are also called laurels and include varieties such as oak, camphor and camellia.

Laurel forest areas are moist and comparatively temperate regions that benefit from the monsoons, and they have a rich farming culture, predominantly of rice cultivation.

The areas in Japan that correspond to evergreen broadleaf forests are forests of oak (Japanese beech), a temperate deciduous broadleaf tree. So natto culture has been passed down in comparatively temperate areas.

Warm and Humid

Both the laurel forest regions of Asia and the beech forests of Japan have a climate that is comparatively warm and also humid.
The right temperature and humidity are essential for soybean fermentation by Bacillus subtilis, the type of bacteria that includes the natto bacillus.

Even now, Asian natto with the exception of Japan's natto and South Korea's cheonggukjang is fermented naturally using natural Bacillus subtilis derived from vegetables. The warm and humid climate and the ready availability of laurel leaves to serve as containers for the natto are favorable conditions for fermenting natto in Asia.

Locations in Japan

In the natto regions in Japan, a culinary culture that uses natto as both a seasoning for umami dashi (soup stock) and as an ingredient in dishes has been passed down to the present day in the same form as in ancient Japan and other parts of Asia.
This is evident most clearly in the Tohoku region.

Miso soup with natto, and natto mixed with salt and malted rice and then aged again (in other words, refermented natto), are eaten in various parts of the Tohoku region to this day.
When goto natto and Yukiwari natto (hikiwari natto, natto made from ground soybeans, to which salt and rice malt have been added) are made into soup stock, they are ideal as a side dish to be eaten with rice, or as something to nibble on while drinking alcohol.

Miso soup with natto is eaten in other parts of Japan as well. These include the Boso region of Chiba Prefecture, where it is known as tozo and is a traditional food of the area, and a temple in Kyoto, where it is called Myoshinji-jiru. But the Tohoku region is said to be its place of origin.

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