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View Full Version : Soy sauce: shoyu, usukuchi shoyu, and tamari



J. A. Crippen
3rd April 2002, 11:48
I'm not asking a question, but giving an answer... A friend asked me recently why I cooked with more than one type of soy sauce, and the answer I gave him ("because that's how I learned!") seemed insufficient. I did a little research and thought I should share... ^_^

There are three different kinds of soy sauce, or shoyu used in Japanese cooking. Shoyu is made with soybeans, wheat, spring water, koji (rice mold, Aspergillus oryzae), and sea salt. Soaked and steamed soybeans are mixed with roasted and cracked wheat and then inoculated with koji and left to ferment for a couple days, then combined with water and left to ferment for up to a year. The mixture is then pressed to separate the mash from the liquid, then the resultant shoyu is filtered and heat treated (stopping fermentation).

The three different kinds of shoyu are koikuchi shoyu, the typical shoyu found on store shelves, usukuchi shoyu, a lighter colored and weaker shoyu, and tamari made only from soybeans.

Koikuchi shoyu is the typical ingredient in Japanese cooking. Usukuchi shoyu is made with less strongly roasted wheat and with more salt which slows the fermentation process. Mirin may also be added to the mixture. Usukuchi shoyu is lighter in color and is used where a less strong flavor and lighter, less brown color are desired. The salt content of usukuchi shoyu is slightly higher than koikuchi shoyu because of the extra salt used to slow fermentation. Usukuchi shoyu should not be confused with 'lite' or reduced-salt shoyu. The latter is a modern invention for those wishing to reduce their salt intake. 'Lite' shoyu is avoided by Japanese food lovers because other chemicals and preservatives are added to it to make up for the reduced salt content.

Tamari is traditionally made in Gifu, Mie, and Aichi prefectures. It is made from only soybeans, without wheat, and with only a small amount of water in comparison to shoyu. Tamari is much darker than shoyu, and thicker, with a much richer flavor. Tamari's strength lends it to use as a condiment more than as a basic ingredient in dishes. In sauces like tsukejiru (noodle dipping sauce used for eg zarusoba) a large amount of shoyu is used but a small amount of tamari is added near the end of the cooking process to enhance the flavor.

Don't keep shoyu in plastic containers. It can discolor them and because plastic is more porous than glass shoyu kept in plastic containers oxidizes faster, and oxidized shoyu tends to be less flavorful and tastes more like heavy salt water (due to the oxidation and decay of the many complex chemicals that make up its flavor). For the same reason, if buying large containers of shoyu they are best kept refrigerated, and small containers used for daily use. Tabletop containers like those sold by Kikkoman and Yamasa which have open holes are no good. Better choices are bottles which have airtight and watertight caps. If you use a lot of shoyu however these tabletop containers are perfectly workable since the contents are exhausted long before their oxidation becomes a problem; hence their popularity with restaurants (most of which refill their shoyu bottles every day).

In frying and simmering shoyu is best used near the end of the cooking process. Heat breaks down the amino acids and vitamins that are preserved in it, and hot temperatures also reduce the flavor. Thus when stir-frying shoyu should usually be added near the end of cooking, rather than at the beginning, because most of the flavor and nutritional value would otherwise go up in the steam. To get food to retain more of a shoyu flavor simply soak it in the shoyu before cooking.

Koikuchi shoyu is on average 17 to 18 percent salt, usukuchi shoyu about 19 to 20 percent. It tends to have a pH of about 4.8 and a low alcohol content, which makes it very useful in food preservation. Because of its popularity it is widely available, even in bulk, and is thus convenient for pickling and preserving, as well as cooking.