Illustrated Japanese Culture
醤油
Shōyu is Japanese soy sauce, used for dipping, seasoning and cooking. Its varieties differ in ingredients, colour and flavour. The familiar dark koikuchi is one of five types in the Japanese Agricultural Standards; a type is separate from its manufacturing method or grade.
01
Soybeans or processed defatted soybeans supply protein; wheat supplies starch. In a common naturally brewed koikuchi process, steamed beans and roasted, cracked wheat are mixed in roughly equal amounts. Other types use different proportions. Marudaizu, or whole-soybean, describes the ingredient choice.
The prepared ingredients are inoculated with kōji mould. Its enzymes break proteins into amino acids and starch into sugars. The resulting soy-sauce kōji is mixed with brine to form moromi, the fermenting mash.
Salt-tolerant lactic acid bacteria and yeasts work in the moromi, developing acidity and aroma as the mash ferments and matures over months. Brewers then press it to separate liquid from solids. The freshly pressed liquid is called kiage shōyu.
The liquid is clarified, then commonly heat-treated, filtered and bottled. Heating is called hiire. Products sold as nama shōyu omit hiire and use other microbial-control methods, such as filtration.
02
Koikuchi serves as a dipping sauce and a cooking seasoning. Its dark colour can colour a dish as well as season it. The Japanese type name is more precise than “dark soy sauce”, which is used for different products in other cuisines.
Usukuchi is useful when a cook wants to season ingredients without darkening them as much. It generally has slightly more salt than koikuchi. The word describes a paler type, not a reduced-salt product.
Tamari is made primarily from soybeans and is associated with central Japan. Some products also contain wheat. The name alone therefore does not establish that a bottle is wheat-free.
For saishikomi, freshly pressed soy sauce replaces the salt water used to start the mash. Associated with Yanai in Yamaguchi, it produces a deeply coloured seasoning.
Shiro uses mainly wheat and has a very pale colour. It is associated with Hekinan in Aichi. These regional associations help explain the types’ histories, although production and use now extend beyond those places.
03
Honjōzō is brewing from kōji and brine. In kongō jōzō, amino-acid seasoning liquid and related ingredients are added to the mash before further fermentation and maturation. Kongō blends such seasoning liquids into kiage soy sauce. The two mixed methods are not the same process.
Nama shōyu means a product without hiire. Ki shōyu has a separate use for a qualifying naturally brewed sauce and, in cooking, soy sauce used without dilution with stock or other seasonings. Kiage names the freshly pressed liquid. These similar-looking terms answer different questions.
JAS grades include special, upper and standard grades. Reduced-salt labels, sweetened styles and whole-soybean ingredients describe other properties. Dashi soy sauce and noodle dipping sauces combine soy sauce with additional seasonings. Check the actual ingredient and nutrition labels, including wheat where relevant.
04
Ancient hishio included several kinds of salted, fermented preparations. Such seasonings appeared in the Japanese court diet during the Nara and Heian periods. They provide background to soy sauce, while differing from the bottled liquid familiar today.
A tradition associated with Yuasa links the monk Kakushin, Kinzanji miso and liquid collected from the fermenting mixture. The story is part of the town’s brewing heritage. Written names for soy sauce appear in sixteenth-century records, including the 1568 Tamon’in diary and a dictionary published in 1597.
05
Edo-period brewing developed in western centres and in the eastern towns of Noda and Chōshi. Kantō producers gained ground in the Edo market during the nineteenth century. Surviving brewery rankings and illustrated accounts show an organised commercial trade.
Soy sauce travelled through Nagasaki to other parts of Asia and to Europe during the Edo period. Glass kelder bottles and ceramic “comprador” bottles were among the containers used in trade. Their shapes belong to the history of transporting the liquid, not just serving it at a table.
06
Mechanisation and imported raw materials expanded after the Meiji period. Wartime shortages encouraged alternative ingredients and new manufacturing methods, including acid-hydrolysed seasoning liquids. Naturally brewed and mixed methods continued alongside one another after the war.
Sweetened soy sauces became more widespread in Kyūshū after the Second World War. Preferences vary within the region, and sweetness is a separate choice from the five JAS types.
JAS standards for soy sauce were established in 1963. Kikkoman introduced its tabletop dispenser in 1961 and began production at a US factory in 1973. Later packages were designed to limit contact with air after opening.
07
Exposure to air gradually darkens soy sauce and changes its aroma. Keep an ordinary opened bottle tightly closed and refrigerated. Air-excluding packages have their own storage instructions, so follow the label rather than assuming all bottles keep in the same way.
Koikuchi or tamari names a type; honjōzō or a mixed method describes how it is manufactured.
Soybeans supply protein and wheat supplies starch.
The mash of soy-sauce kōji and brine that ferments and matures before pressing.
No. It is paler and usually contains slightly more salt than koikuchi.
No. Some products contain wheat, so the label must be checked.
Freshly pressed soy sauce.
No. It means no hiire heat treatment; retail products receive suitable microbial control.
Kongō jōzō adds seasoning liquids before further fermentation and maturation; kongō blends them into kiage sauce.
Through Nagasaki.
Contact with air starts oxidation, which darkens the sauce and changes its aroma. Ordinary opened bottles are best kept closed and refrigerated; follow any package-specific instructions.