What Is Soy Sauce?

Soy sauce and soybeans on wooden table

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You're probably already familiar with soy sauce. This salty, umami-packed flavor bomb of a condiment has broken beyond the bounds of Asian cuisine to add an x factor of savoriness to everything from barbecue sauce to chili. Ever wondered what's in soy sauce? And if its sodium content should actually be a concern? Let's find out.

What is Soy Sauce?

Soy sauce is a brown, salty liquid condiment made by fermenting soybeans or breaking them down with acid. This process is called hydrolization. This releases sugars as well as umami elements and develops the brown color for which soy sauce is known. Sometimes, in modern day production, additional brown coloring is added.

What does It taste like?

If you've never slurped soy sauce by itself—and there are hundreds of varieties by the way—imagine the most savory chicken broth you can think of, reduced down until it's jam packed with richness, umami, and flavor. That's what soy sauce tastes like. It's not just salty; it's also earthy, savory, and even a little sweet.

How to Use It

The short answer is to use it anywhere you would salt, or even in addition to salt. The long answer is that it's a basic way of building a depth of flavor. It doesn't just work well in Asian cuisine; lash it into soups, stews, casseroles, and marinades. You won't necessarily be able to taste the soy sauce in the final product; it'll just have a dimension of umami that it otherwise wouldn't have.

How is Soy Sauce Made?

All cultures have a sauce that is used to stretch salt, which can be hard to obtain and very expensive in areas not adjacent to the sea. Soy sauce was developed in China during the Han dynasty (B.C. 206 to A.D. 220). Soybeans were boiled, wheat or barley was added, added wheat or barley, it was allowed to ferment, and then added water and salt was added. Korea was soon using a similar process. It was also common for people to omit the wheat or barley altogether, making soy sauce traditionally a gluten-free product. (Today, most commercial soy sauces contain wheat.) Soy sauce was introduced to Japan by Chinese Buddhist monks around A.D. 600, but it didn't make its way to Europe until the 1700s.

The technique of making soy sauce has changed over the years, going from a process that can take months to one that produces a finished product in a matter of days.

The traditional method for brewing soy sauce requires multiple steps and can take days to months to complete, depending on the recipe. Soybeans are first cooked to soften the bean, and then bacterial and fungal cultures are added to begin the fermentation process. Roasted wheat or other grains may also be included to provide a unique flavor.

The soybean culture mixture is then combined with a salt brine and allowed to “brew” for a specific amount of time. During this process, the microorganisms break down proteins and sugars that are naturally found in the soybeans into numerous compounds that create the complex flavor and color of soy sauce.

After the fermentation process, the mixture is pressed to extract the dark brown, flavorful liquid. (The resulting solids are often used as animal feed.) Before the extracted liquid is packaged and sold as soy sauce, it is pasteurized to eliminate any harmful microorganisms and filtered to reduce particles and other debris.

Advancements in food production have led to a faster, less expensive method of producing soy sauce, which uses acid-hydrolyzed vegetable protein. This method only requires a few days and produces a more consistent product with a longer shelf life. Traditionalists reject this method, as it does not create the depth of flavor found with the traditional brewing method.

Is Soy Sauce Bad For you?

Soy sauce does contain high amounts of sodium, with leading brands containing roughly one third of your daily recommended intake (RDI) of sodium per serving. However, low sodium versions of leading brands can have just half of that, or 15% of your RDI. It's also been pointed out that one tablespoon of soy sauce has approximately one tenth of the sodium as one tablespoon of salt, making it less salty by volume. Ultimately, it's up to you to be judicious with your salt intake and limit how much you use.

You may have also heard concerns about MSG, or monosodium glutamate. Glutamic acid (which MSG comes from) occurs naturally as a byproduct of the fermentation process, and MSG is sometimes added to commercial soy sauce to enhance the flavor. the Is it bad for you? The short answer is probably not. In fact, most people do not have an adverse reaction to MSG. Furthermore, a 2016 study failed to find significant proof that MSG causes headaches, which is commonly thought to be an indicator of MSG sensitivity.

That said, others in the scientific community have raised concerns about other properties of commercially produced soy sauce. Because the modern production process has changed greatly, many contemporary brands rely on chemicals and additives to speed up or mimic the fermentation process.

Studies have found commercially produced soy sauce to be high in chloropropanols, which the European Union limits as a toxic substance in food products. According to a study published in Critical Reviews in Food Science and Nutrition, soy sauce can contain significant amounts of this type of compound. Note that traditionally fermented soy sauce does not contain these compounds, which are a result of modern food science, and not limited only to soy sauce production.

Soy sauce does include soy, and sometimes wheat. People with soy and wheat allergies (and of course, celiac disease, which is basically an intolerance to gluten, which is found in wheat) should look carefully at labels before consuming.

Some researchers have also found significant health benefits in soy sauce. A 1999 study by researchers at the National University of Singapore found that dark soy sauce may contain up to 10 times the antioxidants found in red wine.

Soy Sauce Varieties

Varieties depend on the ingredients used, the method used to create the sauce, and the region in which it is made. In the United States, there are a few main varieties that may be found in grocery stores or listed in recipes: light, dark, low sodium, and tamari.

Light soy sauce is the thin, brown liquid that most Americans refer to as regular soy sauce. It is a good all-purpose seasoning and condiment. Dark soy sauce has had molasses or caramel added after the brewing process, which thickens the sauce slightly and produces a sweeter, more complex flavor.

For people watching their salt intake, a low-sodium soy sauce may be the sauce of choice. Salt is an important component in the production of soy sauce because it acts as an antimicrobial agent. Most low-sodium soy sauces are made using the acid-hydrolyzed vegetable protein method, which does not utilize bacterial and fungal cultures and therefore requires less salt. 

Tamari is a Japanese soy sauce that is made with only soybeans and no wheat or other grains. Tamari has a very clean flavor and is favored by those who follow a wheat- or gluten-free diet.

Where to Buy Soy Sauce

Find light soy sauce in the supermarket in the Asian foods section or condiments section. Well-stocked markets should also have dark soy sauce and tamari. You can find traditionally-fermented varieties at international grocers, along with lesser known types, like white soy sauce.

Substitutions

You may need a soy sauce substitute if you have simply run out of it and can't make a quick trip to the store. The umami element can be added by using Worcestershire sauce, Maggi seasoning sauce, beef stock or bouillon, coconut aminos, or liquid aminos. You would need to adjust for the salt and sweetness usually provided by soy sauce as well.

One common need for substitution is for those on a low-sodium diet. A soy sauce substitute can be made using low-sodium beef broth, molasses, balsamic vinegar, red wine vinegar, sesame oil, garlic powder, and black pepper. This is simmered to reduce and concentrate it.

Storage

Unopened soy sauce is shelf stable and can be kept in a cool, dark place. Once opened, however, soy sauce should be kept in the refrigerator for optimum flavor. The high salt content of most soy sauces will prevent dangerous microorganisms from proliferating at room temperature, but the delicate flavor compounds produced during the fermentation process are best protected under refrigerated conditions. Low-quality soy sauces are less likely to have a noticeable degradation in flavor if stored at room temperature.

Soy Sauce Recipes