Soy Sauce Day (Shoyu no Hi)

What Is Soy Sauce Day?

October 1 is "Soy Sauce Day" in Japan. The soy sauce industry, including the Japan Soy Sauce Brewers Association, has marked October 1 as Soy Sauce Day since 2002 (Heisei 14). In old Japan, October was the season for storing and processing the harvest, and brewers started new batches of soy sauce mash at this time. October also corresponds to "tori," the 10th of the twelve zodiac signs, and the character for tori (酉) comes from the shape of a jar for holding liquor; it appears in both 醤 (the "sho" of shoyu) and 酒 (sake). Because of these close ties to brewing, this date was chosen.

A History of Soy Sauce

Soy sauce is said to trace its origins to "hishio," a fermented seasoning from ancient China.

• Yuasa and Kinzanji miso: In the Kamakura period, the Zen monk Kakushin (Hotto Kokushi) brought back the method for making Kinzanji miso from Song China. The liquid that collected at the bottom of the barrels during production is said to have been the beginning of soy sauce. Yuasa in Kishu (today's Yuasa, Wakayama Prefecture) is regarded as the birthplace of soy sauce.
• Kanto soy sauce: In the Edo period, Noda and Choshi in today's Chiba Prefecture became major producers of koikuchi (dark) soy sauce, supporting Edo's food culture.
• Going abroad: In the Edo period, soy sauce was exported to Europe through the Dutch East India Company. Today it is used in many countries around the world.

The Five Types of Soy Sauce

Japan's JAS standards divide soy sauce into five types.

• Koikuchi (dark): The most common type, accounting for about 80% of domestic shipments.
• Usukuchi (light-colored): Born in Tatsuno, Hyogo Prefecture, it is used in Kansai cooking to preserve the color of ingredients. It is actually saltier than koikuchi.
• Tamari: Made mainly from soybeans, thick and rich in umami, and produced mostly in the Chubu region.
• Saishikomi (double-brewed): Brewed with soy sauce instead of brine, making it dark in color and flavor. It is said to have originated in Yanai, Yamaguchi Prefecture.
• Shiro (white): Made mainly from wheat, pale amber in color. It is said to have originated in Hekinan, Aichi Prefecture.

Soy Sauce Trivia

• The aroma: Soy sauce's aroma is made up of many compounds produced through fermentation, aging and heating.
• Umami synergy: The glutamate in soy sauce tastes stronger when combined with inosinate from bonito flakes or guanylate from shiitake.
• Color change: Soy sauce darkens and loses flavor as it oxidizes on contact with air. After opening, keep it in the refrigerator and use it up soon. Airtight bottles that limit exposure to air have become common in recent years.
• JAS grades: Under JAS standards, grades of "tokkyu" (special), "jokyu" (superior) and "hyojun" (standard) are set based on factors such as nitrogen content, an indicator of umami.

Ideas for Soy Sauce Day

• Compare different types - koikuchi, usukuchi, saishikomi - with sashimi or chilled tofu.
• Try soy sauce from a small local brewery, such as one brewed in wooden barrels.
• Check your kitchen for opened soy sauce left at room temperature.
• Cook a dish with plenty of dashi and a little less soy sauce.

Something to Remember on Soy Sauce Day

October 1 is a day to rediscover the history and depth of soy sauce, an essential part of the Japanese table. Said to have started as a by-product of miso in the Kamakura period, soy sauce has developed distinct regional flavors over centuries. Today, pay a little extra attention to the soy sauce you use in your everyday cooking.