Shoyu (Soy Sauce)

The Defining Flavor of Japanese Cuisine

Shoyu, or soy sauce, is one of the world's oldest seasonings. A fermented and aged product, generally made of soybeans, grains, and salt, its name is a bit of an anomaly, as the characters used to write shoyu actually mean fermented food oil—no mention of soy beans! Shoyu has always been deeply embraced by the Japanese people as a seasoning used to enhance the specific flavor of Japan's seasonal foods, and it is impossible to think of the cuisine separately from shoyu. In fact, there is the opinion that its applicability and versatility is the reason that the use of spices and herbs never really developed in Japan. The appeal of shoyu is simple—it magnificently brings out the flavor of any food without overpowering the natural flavor regardless of how the food is prepared. Nowadays, the use of shoyu has spread worldwide, lending depth and vividness to the global food culture. Let's focus in on this all-purpose beloved condiment.

History of Shoyu

It's said that in 1260, about midway through the Kamakura period (1185-1333), a Buddhist monk from a temple situated in today's Wakayama prefecture made what would become the predecessor of shoyu. This monk, who had resided in China for a while, taught some of the Wakayama locals the process of making a type of miso with soybeans, vegetables, and salt. During the fermentation process, he noticed that some liquid had accumulated at the bottom of the barrel holding the miso that bore a resemblance to the tamari shoyu of today. Upon sampling it and finding it palatable, he decided to use it as a seasoning, and, according to legend, thus evolved the origin of shoyu!

In 1530, at the end of the Muromachi period, this liquid was being produced as a seasoning in its own right, and mention of it appears in text for the first time in 1536. Because the salt used in its production was still quite an expensive commodity, this early shoyu was reserved only for the aristocracy, monks, and the warrior class.

Birth of Koikuchi Shoyu

About 1600, increased production of what is known today as tamari shoyu took hold as popularity grew among the general populace. During the approximate one hundred year period from the latter half of the 16th century to the latter half of the 17th century, handcrafted shoyu production developed in the areas we know as Kyoto, Wakayama, Hyogo, and Chiba prefectures. In the early years of production, usukuchi shoyu, or "light" shoyu, referring to its color, made in the western or Kansai area (including Kyoto, Wakayama and Hyogo) was considered the shoyu of choice.

Around 1700, Edo (Tokyo's former name) was undergoing major urbanization, and as the number of laborers greatly increased and the "dining-out" culture blossomed, the shoyu produced in the area in and around Chiba prefecture (Kanto, or eastern area) began to exert its influence and gain popularity. Using locally harvested high quality soybeans and increasing the amount of wheat, a new shoyu recipe with an aromatic, rich flavor was created—the koikuchi, or "dark" shoyu.
Koikuchi, which perfectly complemented and enhanced sushi, as well as other Edo-style seafood cuisine, created a combination that proved to be a favorite with the locals. The koikuchi so highly favored by the folks born and bred in Edo continued to be developed and refined, and with it the model for today's Japanese cuisine took root. It's no exaggeration to say that some of the most well-known representative members of the Japanese diet, including sushi, tempura, sukiyaki, shabu-shabu, unagi no kabayaki, and soba, could never have been created without the existence of koikuchi shoyu. The Kanto version of shoyu became the standard shoyu, and its use spread far and wide throughout the country.

Shoyu—The Taste Quintet

Shoyu contains the five elemental tastes: sweet, salty, bitter, sour and umami. Some of the individual tastes are not easily discernable, but through their combinations create the flavor of shoyu that we love. The reason that it is possible for a product whose main ingredients are soybeans, wheat, and salt to support such a complex flavor profile is due to the chemical reactions that occur between the taste and aroma agents which create a synergistic effect. The result is a perfectly harmonized, tastefully balanced shoyu!

Did you know that if you remove the salt from shoyu it actually tastes sweet? The sugars in shoyu (about 15 different types) include glucose and galactose (a sugar that is less sweet than glucose), among others. By volume, shoyu is about 3-5% sugar. This sweetness has an overall mellowing and softening effect on the shoyu.

Shoyu contains approximately 15 types of organic acids, the primary one being lactic acid, which gives it a higher antibacterial effect than a saline solution with the same density as shoyu. The sour taste softens the powerful saltiness and helps to round out the flavor, and the pH level (measure of acid and alkaline) of honjozo (meaning naturally brewed) shoyu is said to allow the shoyu to reach the epitome of aroma, flavor and color.

Shoyu contains 5 to 6 times the amount of salt in seawater, and it is this high salinity that has an antibacterial effect. The reason shoyu doesn't taste as salty as seawater is because of the mitigating effects of the sour, umami, and other agents.

These agents don't impart a noticeable bitterness, rather they provide a satisfactory "punch" and a definitive flavor and richness to the shoyu.

Umami is the "fifth" taste sense, discovered later than the other taste senses. Sometimes it is known as "savoriness," "meatiness" or "brothiness." The proteins in soybeans and wheat are broken down into twenty different types of amino acids during the brewing duration via their interaction with koji mold. These amino acids are what give shoyu its umami, but it is glutamic acid that provides the strongest umami taste.

Shoyu's Aroma
Shoyu's flavor is made up not only of taste, but of aroma as well. Shoyu contains several different aromas delicately blended together which include rose petal, apple blossom, fruit, whiskey and coffee. Over 300 types of aromatic substances have been detected! The basic characteristic aroma of shoyu (abbreviated as HEMF) is actually the result of a layered combination of many varieties of aromatic substances that have joined together, much as the music of individual instruments join together in an orchestra to create a symphony—in this case, a symphony that we can taste!
Cooking with shoyu releases an even more fragrant odor which is due to a substance called melanoidin which is formed when amino acids and sugars bond together during the heating process. (As an added plus, it is said that melanoidin also possesses anti-oxidative properties.) This toasty, pleasant fragrance has been put to good use in teriyaki flavoring, which Americans are also quite fond of! It is these numerous aromas in shoyu combined with the 5 elemental tastes that give shoyu its unique, extremely palatable and versatile flavor.

Types of Shoyu

Considered the standard shoyu, koikuchi sales enjoy 83% of the shoyu market in Japan. It is usually made with equal amounts of soybeans and wheat, which are fermented, then aged. With its full-bodied taste, pleasant fragrance and beautiful translucent reddish-brown sheen, it is perfectly suited for use as a table-top condiment and just as well-suited for use in dipping sauces, grilling and stewing. This is the shoyu that Kanto folk and those from the northern parts of Japan favor.

This shoyu is lighter in color and fragrance than koikuchi, but don't let that fool you into thinking it is low-salt; it is actually saltier! Developed in the Kansai region, the ingredients and production method are mostly the same as for koikuchi, but in order to develop the lighter color, more salt is used, and the fermentation and aging processes are conducted at a lower temperature. Not used as a table-top condiment because of its weak fragrance and saltiness, it is indispensable in traditional Kyoto cuisine and other dishes that showcase the original colors and aromas of the ingredients.

Tamari is a thick type of shoyu made from mostly soybeans with usually just a little wheat. The tamari-like substance mentioned earlier was the prototype for shoyu. The tamari that we know today is darker and more aromatic than koikuchi, and it is an excellent choice as a dipping sauce for sashimi and sushi, and can also be used as a table-top condiment. When heated, it develops a lovely deep reddish hue and creates a beautiful glaze seen in teriyaki, tsukudani, senbei, etc.

Gen'en (reduced sodium) shoyu, was developed for people concerned with their sodium intake. It is made by reducing the sodium content of koikuchi via a special process that leaves all the other flavor agents, such as umami and aroma, intact. The amount of sodium is about half the amount in regular koikuchi.

Shoyu, slowly and carefully crafted with stringently selected ingredients, including water of the finest quality, has no peer as an all-purpose condiment born of Japan's natural landscape and culture. Even countries that didn't originally use shoyu have adopted it and found that it brings a new level of flavor and excitement to their dishes. It is now one of the fundamental condiments in kitchens all over the world, adding zest to stews and soups, sauces and chutneys, sloppy Joes—and even desserts! So make some space in your spice cabinet for a bottle (or two) or one of the glories of Japanese dietary culture—shoyu!