How Japanese soy sauce is made
See how Japanese soy sauce has been made for 750 years in this fascinating short film by Mile Nagaoka.
Japanese soy sauce, or Shoyu
Stand in the international foods aisle of a mainstream grocery store and you’re most likely to see Japanese-style soy sauces, known as shoyu. Traditional Chinese soy sauces were made with 100% soy (some modern Chinese soy sauces contain wheat too). When the brewing method made its way to Japan, the recipe was modified to use an even ratio of soybeans and wheat, resulting in a sweeter, less harsh flavor. Japanese-style soy sauces tend to be clearer and thinner than Chinese sauces.
Koikuchi (dark): Japanese soy sauces are split into dark (koikuchi) and light (usukuchi) with the former being more commonly used. Most major supermarket brands available in the U.S., like Kikkoman’s All-Purpose Naturally Brewed Soy Sauce don’t indicate a type on the label, but are considered a “dark” soy sauce, according to Shizuo Tsuji, author of Japanese Cooking: A Simple Art.
Kikkoman’s All-Purpose is produced in the company’s factory in Walworth, Wisconsin. “Less Sodium” soy sauce is made the same way as regular soy sauce, but about 40 percent of the salt is taken out post-brewing. Dark Japanese soy sauces have a deeper color, but actually taste less light. A good all-purpose choice, they are best used in marinades and basting sauces, but are perfectly acceptable for dipping or stir-fries as well.
Usukuchi (light): These are lighter and thinner than their darker, richer counterparts, but have a more assertive, salty flavor and a slight sweetness from the addition of mirin, a sweet rice wine. Primarily used in the Southern Kansai region of Japan, light soy sauces are used to season ingredients without turning the ingredients into a darker color. They can be used in place of dark soy sauce, but they should be used more sparingly because of their intense flavor.
Tamari: More similar to traditional Chinese soy sauce, this is made with soybeans and little to no wheat. Tamari started in the fifteenth century as a by-product miso (fermented soybean paste) production, and was completely devoid of wheat. These days, many tamari-style soy sauces actually contain a trace of wheat, though most major brands like San-J, Wan Ja Shan, Eden Organic and Ohsawa offer gluten-free versions.
With a higher soybean content, tamari has a stronger flavor and is ideally used as a dipping sauce. If you have a wheat allergy, tamari can be a good alternative to shoyu, though you should always be sure to check the ingredients list for the presence of wheat.
Other Japanese Soy Sauces: While tamari is made with more soybeans, shiro, or white soy sauce, is brewed with more wheat. It has a lighter color and flavor. It’s typically used as a dipping sauce for sashimi made with mild, white-fleshed fish where a darker sauce would overpower and discolor the delicate slices. Saishikomi, or “twice-brewed” soy sauce, has a stronger flavor than tamari.
To produce it, the saltwater brine in the fermentation stage of standard shoyu is replaced with a previous batch of already-brewed soy sauce. Shiro and saishikomi are not as commonly found in stores compared to other soy sauces.