How Is Soy Sauce Made and Is It Bad for You?
Soy sauce is a very flavorful ingredient made from fermented soybeans and wheat.
It originated in China and has been used in cooking for over 1,000 years.
Today, it’s one of the best-known soy products worldwide. It is a staple ingredient in many Asian countries and used widely across the rest of the world.
The way it’s produced can vary significantly, causing significant changes in flavor and texture, as well as health risks.
This article investigates how soy sauce is produced and its potential health risks and benefits.
Soy sauce is a salty liquid condiment traditionally produced by fermenting soybeans and wheat.
It is thought to have originated from a Chinese product called “chiang” over 3,000 years ago. Similar products were developed in Japan, Korea, Indonesia and across Southeast Asia.
It first came to Europe in the 1600s through Dutch and Japanese trading (1, 2).
The word “soy” comes from the Japanese word for soy sauce, “shoyu.” In fact, the soybean itself was named from soy sauce (1).
The four basic ingredients in soy sauce are soybeans, wheat, salt and fermenting agents like mold or yeast.
Regional varieties of soy sauce may have varying amounts of these ingredients, resulting in different colors and flavors.
SUMMARYSoy sauce is a salty condiment produced through the fermentation of soybeans and wheat. It originated in China and is now produced in many Asian countries.
Many different types of soy sauce are available. They can be grouped based on their production methods, regional variations, color and taste differences.
Traditional Production
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.
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.
SUMMARYTraditional 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
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 .
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.
SUMMARYChemically 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.
Regional Differences
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 ).
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.
SUMMARYThere 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.
Below is the nutritional breakdown for 1 tablespoon (15 ml) of traditionally fermented soy sauce (7).
- Calories: 8
- Carbohydrates: 1 gram
- Fat: 0 grams
- Protein: 1 gram
- Sodium: 902 mg
This makes it high in salt, providing 38% of the Recommended Daily Intake (RDI). While soy sauce has a relatively high amount of protein and carbohydrates by volume, it’s not a significant source of those nutrients.
In addition, the fermentation, aging and pasteurization processes result in a highly complex mix of more than 300 substances that contribute to the aroma, flavor and color of soy sauce.
These include alcohols, sugars, amino acids like glutamic acid, as well as organic acids like lactic acid.
The amounts of these substances change significantly depending on the base ingredients, the strain of mold and the method of production (3, 4).
It is these compounds in soy sauce that are often linked with its health risks and benefits.
SUMMARYSoy sauce is high in salt, providing 38% of the RDI in 1 tablespoon. It contains more than 300 compounds that contribute to flavor and aroma. These compounds may also be associated with health risks and benefits.
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