Harvesting Sea Salt: How Salt Is Made In Japan

Sugar. Salt. Vinegar. Soy sauce. Miso.

Remembered by the mnemonic “sa-shi-su-se-so,” these five ingredients are the pillars of Japanese cooking.

Sugar, vinegar, soy sauce, and miso, all derivatives of plants, arrived in Japan via Chinese traders possibly as early as the Jomon period (between 16000 and 2300 BC). While the Japanese were later able to develop their own methods of producing these products domestically, salt was harder to obtain.

How Sea Salt Is Made In Japan

An essential mineral for the human body, most natural salt used in kitchens around the world originates from salt mines or natural brines (salt springs). However, since Japan lacks any natural salt deposits, the Japanese are forced to look towards the sea. 

But turning seawater into salt is not as easy as one might expect. 

Seawater contains only about 3.5% salt on average. Therefore, to make one 80g (0.18lb) packet of sea salt, it would require over 2 liters (0.5 gallons) of sea water. However, it is not so much the amount of water required that is the problem, but rather how to remove it. Japan’s humid climate makes evaporation a long, arduous process, while simply boiling off the water would require an extraordinary amount of fuel. 

Thus, many different methods were developed throughout Japan to obtain this essential mineral. Examples of these unique methods include incorporating salt from seaweed (as in moshio produced in the Seto Inland Sea), or by running seawater through finely branched bamboo stalks (as in aguni no shio produced in Okinawa).

Salt production grew in many coastal regions throughout Japan, peaking in the Edo era when several “salt roads” developed for the sole purpose of transporting freshly harvested sea salt to salt-deprived inland cities. But this “golden era” of locally produced salts came to a halt in 1905 when the Japanese government established a monopoly on salt production in order to fund the Russo-Japanese War. 

The government standardized the industry and, in an effort to modernize, became the first country to provide salt produced by an ion exchange process (aka “table salt”) to its citizens in 1971. But with table salt lacking many of the health benefits of natural sea salt, and local communities feeling their traditions slowly fading away, doctors, researchers, and community leaders eventually put enough pressure on the Japanese government to abolish the salt monopoly in 1997. 

Today, there are an estimated 700 different independent salt producers throughout Japan producing over 1500 different varieties of salts harvested directly from the sea. 

You can support these local businesses by trying moshio produced by hand in Hyogo Prefecture. And for those looking to learn more about how sea salt is harvested in Japan, feel free to visit the Tobacco & Salt Museum in Tokyo or the Salt Road Museum in Niigata.

About the author:

Kimberly Matsuno

Kimberly Matsuno is a professional content writer and editor from the US. Having spent several years living in the Japanese countryside, Kimberly holds a particular fondness for Japanese culture and cuisine—particularly anything made with shiso. You can view more of her work at kimberlymatsuno.com.