It is said that the roots of Shoyu (soy sauce) can be traced back to Kokusho (sauce made from grain) and was imported to Japan from the Asia continent in the Asuka period (538-710 AD).
Kokusho was sauce made by pickling grain in salt and fermenting them.
It has been gradually adapted to climate and culture in Japan by utilizing their knowledge and techniques.
Japanese-taste Kokusho was produced in the Nara period (710-794 AD) and the Umami taste was established in their daily lives.
Shoyu has been developed after the sixteen century. However, the basic taste, which attracted ancient Japanese, has been passed on generation.
- Seiichi, Hayashi (1997), “Genzon Suru Saiko no Ryourisho-Qimin Yaoshu” (“The Oldest Extant Cooking Document-Essential Techniques for The Welfare of The People”), Yusankaku Inc., ISBN 4639014708
- Masataka, Sekine (1969), “Nara Choushoku Seikatu no Ryourisho” (“Research for Breakfast in Nara”),Yoshikawakobun Inc., ISBN 464202039X
- Tamotu, Yokotsuka (2004), “Nihon no Shoyu” (“Japanese Soy Sauce”), Life Research Press Inc., ISBN 4906472710
Reiko, Hayashi (2005), “Nihon no Aji –Shoyu no Rekishi” (“Japanese Taste-the History of Soy Sauce”), Yoshikawakobun Inc., ISBN 4642055878