Many different types of soy sauce are available. They can be grouped based on their production methods, regional variations, color and taste differences.
Traditional soy sauce is made by soaking soybeans in water and roasting and crushing the wheat. Then the soybeans and wheat are mixed with a culturing mold, most commonly Aspergillus, and left for two to three days to develop.
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Next, water and salt are added, and the entire mixture is left in a fermenting tank for five to eight months, though some types may age longer.
During fermentation, enzymes from the mold act on the soy and wheat proteins, gradually breaking them down into amino acids. The starches are converted to simple sugars, then fermented to lactic acid and alcohol.
After the aging process is complete, the mixture is laid out onto cloth and pressed to release the liquid. This liquid is then pasteurized to kill any bacteria. Finally, it’s bottled (3, 4).
High-quality soy sauce uses only natural fermentation. These varieties are often labeled “naturally brewed.” The ingredients list will usually only contain water, wheat, soy and salt.
Summary Traditional soy sauce is made with a mixture of soybeans, roasted wheat, mold and salt water, which is aged for five to eight months. The resulting mash is then pressed, and the soy sauce liquid is pasteurized and bottled.
Chemical production is a much faster and cheaper method of making soy sauce. This method is known as acid hydrolysis, and it can produce soy sauce in a few days instead of many months .
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In this process, soybeans are heated to 176°F (80°C) and mixed with hydrochloric acid. This process breaks down the proteins in the soybeans and wheat.
However, the resulting product is less attractive in terms of taste and aroma, since many substances produced during traditional fermentation are missing. Therefore, extra color, flavor and salt are added (4).
Additionally, this process produces some undesirable compounds that are not present in naturally fermented soy sauce, including some carcinogens (2).
In Japan, soy sauce that is brewed in a purely chemical process is not considered soy sauce and cannot be labeled as such. However, it may be mixed with traditional soy sauce to lower costs.
In other countries, chemically produced soy sauce may be sold as-is. This is often the type of soy sauce you’ll find in the small packets given with take-away meals.
The label will list “hydrolyzed soy protein” or “hydrolyzed vegetable protein” if it contains chemically produced soy sauce.
Summary Chemically manufactured soy sauce is made by hydrolyzing soy proteins with acid and heat. This method is quick and cheap, but the resulting soy sauce tastes inferior, contains some toxic compounds and may require extra colors and flavors.
In Japan there are many different types of soy sauce.
- Dark soy sauce: Also known as “koikuchi shoyu,” this is the most common type sold in Japan and overseas. It’s reddish brown and has a strong aroma (2, 3, 5).
- Light soy sauce: Also called “usukuchi,” this is made from more soybeans and less wheat, and it has a lighter appearance and milder aroma (2, 3, 5).
- Tamari: Made from mostly soybeans with 10% or less wheat, it lacks aroma and is darker in color (3, 5).
- Shiro: Made almost only with wheat and very few soybeans, it’s very light in color (3).
- Saishikomi: Made by breaking down the soybeans and wheat with enzymes in a solution of unheated soy sauce instead of salt water. It has a heavier taste, and many enjoy it as a dipping sauce (2, 3, 5).
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In China, the tamari-style soybean-only soy sauce is the most common type.
However, today a more modern production method is most common. Soybean meal and wheat bran are fermented for just three weeks instead of several months. This method results in a very different flavor compared to traditionally produced soy sauce (2, 3, 6).
Chinese soy sauces are often listed as “dark” or “light” in English. Dark soy sauce is thicker, older and sweeter and used in cooking. Light soy sauce is thinner, younger and saltier, and it’s more often used in dipping sauces.
In Korea, the most common type of soy sauce is similar to the dark koikuchi type in Japan.
However, there is also a traditional Korean soy sauce called hansik ganjang. It’s made only from soybeans and mainly used in soup and vegetable dishes (3).
In Southeast Asian countries like Indonesia, Malaysia, the Philippines, Singapore and Thailand, the tamari-style sauce is most commonly produced, but many local variations exist (2).
Other varieties include sauces thickened with sugar, such as kecap manis in Indonesia, or those with additional flavors added, such as shrimp soy sauce in China.
Summary There is a great variety of soy sauces across Asia, each with different ingredients, flavors and aromas. The most common type is Japanese dark soy, called koikuchi shoyu, which is made from naturally fermented wheat and soybeans.
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