Soy Sauce Explained: Types, Grades and Yamasa

Most menus that use soy sauce do not mention it. Ours names it once, in an unexpected place — the dessert section — and it names the brewery too: the muhallebi comes with “yamasa soy caramel”. People ask about the soy, and fair enough; soy sauce in a pudding sounds like a dare. Fewer people ask about the other word, which is the more interesting one. Yamasa is a Japanese soy sauce brewery that has been making it in the same fishing town since 1645. This is what soy sauce actually is, how Japan sorts it, and why that particular name ended up on our card.

What soy sauce is

Soy sauce is a fermented liquid, not a flavouring someone mixed up. In the Japanese style, soybeans and wheat are inoculated with koji — a cultivated mould — then mixed with brine and left to ferment. The mash is pressed, and what runs out is shōyu. The fermentation is where the colour, the depth and most of the savour come from; as our post on umami explains, fermented soy products are among the richest everyday sources of glutamate, which is why a few drops make food taste rounder rather than just saltier.

Japanese soy sauces differ from most Chinese ones in one big way: wheat. Most Japanese styles use a substantial share of it, which tends to make them taste slightly sweeter. That matters if you avoid gluten, and we come back to it at the end.

The five kinds Japan officially recognises

Japan’s agricultural standard (JAS) divides shōyu into five types by ingredients and method. You will mostly meet the first one:

Koikuchi (“thick taste”) — the everyday dark soy sauce. It originated in the Kantō region around Tokyo, is made from roughly equal parts soybean and wheat, and accounts for more than 80% of Japan’s domestic production. If a Japanese bottle just says “soy sauce”, it is almost certainly this.
Usukuchi (“thin taste”) — paler but actually saltier, and popular in the Kansai region around Osaka and Kyoto, where cooks want seasoning that does not darken the food. About 14% of production.
Tamari — darker, thicker and richer, made with little or no wheat. Mostly from the Chūbu region, and only around 1.5% of production. It is also the style closest to the soy sauce that first came to Japan from China.
Saishikomi (“twice-brewed”) — brewed using finished koikuchi in place of the usual brine, which makes it very dark and very intense. Under 1%.
Shiro (“white”) — the opposite of tamari: mostly wheat, very little soybean, pale and sweet. Also under 1%.

On top of type, there is how it was made. A label reading honjōzō means the soy sauce is 100% naturally fermented; the other two grades blend in a share (30 to 50%) of chemically or enzymatically hydrolysed plant protein. JAS also grades quality by total nitrogen — standard, upper and special — with tokkyū (special) the highest. If you are buying a bottle for home, “honjōzō” is the word worth looking for.

Where it started, according to the people who make it

Yamasa’s own history tells the origin story the Japanese industry likes best, and it is careful to present it as tradition rather than record. In the Kamakura period, a monk named Kakushin, of Kōkoku-ji temple in Yura in the old province of Kishū (today’s Wakayama), brought back a method for a kind of miso he had learned in China. While teaching it to villagers in nearby Yuasa, a batch went wrong — and the liquid it produced was something like today’s tamari. Yuasa is still called the birthplace of Japanese soy sauce.

The founder of Yamasa, the first Hamaguchi Gihei, came from Hiro, the village next door to Yuasa. In 1645, just 42 years after the Tokugawa shogunate was established in Edo, he crossed to Chōshi, a fishing port on the far eastern tip of Chiba, and started brewing. The company’s own account says Chōshi’s mild winters, cool summers and high humidity suit the koji mould, and that its climate resembles Kishū’s. It also makes a point we think is fair: Yamasa grew alongside Edo itself, in the same era that gave the city its sushi, tempura and grilled eel — all dishes built on soy sauce.

Three details worth knowing about the name

The logo is a pun. The Yamasa mark is a peaked line — a mountain, yama — over the katakana character sa. Read together: Yama-sa.

The small character at its shoulder is an award. The mark carries the character 上 (jō, “upper”) at its top right. According to the company, it records the title of saijō shōyu — “finest soy sauce” — granted by the shogunate in 1864 for quality, and it has stayed on the label ever since as a reminder. In 1895 Yamasa also became the first brewery in the Kantō region appointed purveyor to the Imperial Household.

A soy sauce family is remembered for a tsunami. The seventh head of the house, Hamaguchi Goryō, was back in Hiro when the great Ansei-Nankai earthquake struck in 1854. Reading the sea drawing back, he expected a tsunami and set fire to the harvested rice sheaves stacked in the fields to raise the alarm and get the village to evacuate. The story, Inamura no Hi (“the fire of the rice sheaves”), was retold by Lafcadio Hearn as A Living God and taught in Japanese national school readers from 1937 to 1947. He then paid for a seawall, about 600 metres long and 5 metres high, which survives today as a designated historic site.

There is a science thread too. The company says its researchers in the 1950s learned to produce two of the umami compounds, inosinate and guanylate, industrially from RNA, and that its team found the synergy between those compounds and glutamate — the multiplying effect our umami post is built around. A soy sauce brewery ended up helping explain why dashi works.

Why it is in our dessert

The dish is the muhallebi, and the full line on the Hamilton Road menu reads: vanilla & yoghurt milk pudding, morello cherries in kirsch, yamasa soy caramel, brown butter digestive biscuit. The muhallebi post covers why a soy caramel is not the same thing as a salted caramel, so we will not repeat it here. The short version is that a well-fermented soy sauce brings slow-browned, savoury depth that plain salt cannot, and naming the brewer is a way of saying the choice of soy sauce changes the result — the same way a menu would name an olive oil.

What the menu does not say is which Yamasa product goes in. Yamasa makes many; the card prints only the name. We will not guess at the type, and if it matters to you, ask.

Soy sauce also sits quietly behind other words on our menu. Ponzu, which dresses our steaks and our lamb tartare, is in its common form a citrus sauce with soy added. And shio kombu, on that same tartare, is kelp simmered down in seasoning that traditionally includes soy. Like mentaiko and wasabi, it is one of the Japanese pantry staples that make our Middle Eastern plates taste the way they do.

The practical bits

Soy and wheat. Soy sauce contains soy, and most Japanese soy sauces also contain wheat. If you have a soy, wheat or gluten allergy or intolerance, tell us when you sit down so the kitchen can steer you — including away from dishes where the soy is not obvious from the menu.
At home. For general cooking, a honjōzō koikuchi does almost everything.
Where. Habibi-san, 29 Hamilton Road, Jalan Besar. Tuesday to Sunday, 5pm to 11pm; brunch on Saturday and Sunday, 11am to 2.30pm.

For how the Japanese half of our kitchen fits with the Middle Eastern half, the best place to start is our guide to Japanese food in Singapore. And if you want to taste a 1645 brewery in a milk pudding, book a table and save room.