Recreating Soy Sauce from the Edo Period

The Kikkoman Institute for International Food Culture has succeeded in recreating soy sauce from the Edo period (1603-1867). The project, lasting nearly a year and a half, was carried out jointly with NHK Promotions and was also taped by NHK. The Institute plans to make copies of the video available to the public.

Before the early nineteenth century, soy sauce was mostly kudari shoyu, a name referring to the soy sauce having been “brought down” to Edo (Tokyo) from the Osaka area. From the nineteenth century, however, the use of Kanto jimawari shoyu had risen sharply. This is a soy sauce from the Kanto region, manufactured mainly in today’s cities of Noda and Choshi in Chiba Prefecture.

The Kikkoman/NHK project focused on why Kanto jimawari shoyu replaced kudari shoyu so completely within a period of only about thirty years. Researchers hoped to find some answers by recreating kudari shoyu and comparing it to modern soy sauce, which is believed to possess a flavor close to jimawari shoyu.

There exist no documents or materials on the manufacturing of kudari shoyu; thus the soy sauce was recreated based on a manufacturing method published during the period when kudari shoyu dominated the market (1732). Every effort was made to recreate the actual conditions for soy sauce manufacture during the Edo period: Tools and facilities were recreated to be as similar as possible to those used during the time, while specific types of soy beans, wheat and salt authentic to that era were used when possible.

Fermentation took place from August to December 2004 at Kikkoman’s Goyogura and Rengagura plants located in Noda. The recreated soy sauce was analyzed chemically and it was found that the kudari shoyu used in Edo lacked taste and body because the fermentation period was only four months; its flavor was not as strong as today’s soy sauce because the alcohol content had not been sufficiently fermented.

It seems that Kanto jimawari shoyu may have been preferred to kudari shoyu for the following reasons: 1. It has a savory, rich taste rather than a simple salty taste; 2. It possess a unique taste and flavor; 3. It emits a savory aroma when cooked, which stimulates appetite; and 4. It may serve as a soup for noodles as well as a dipping sauce for dishes like tempura. In summary, kudari shoyu failed to offer the range of color, flavor or flexibility in cuisine that Edo people favored, and only Kanto jimawari shoyu satisfied the palate of the times.

Researchers concluded that the success of the Kanto jimawari shoyu seems to have been owing to manufacturers’ efforts to go beyond kudari shoyu as they sought to develop techniques to control taste, flavor and color by adjusting the period of mash fermentation while mixing in multi-age fermented mash.

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