When you’re standing in the condiment aisle of your local store, one bottle of soy sauce may look much like another. But soy sauces are not all the same. In fact, there are two ways manufacturers make soy sauce: one that relies on the natural process of fermentation and one that takes a chemical shortcut. Although the result looks similar at first glance, they don’t taste or smell the same, and that difference can transform your cooking and dining experience.
Traditionally Brewed Soy Sauce vs. Chemical Soy Sauce: The Power of Fermentation
How is traditionally brewed soy sauce made?
A Japanese fermented soy sauce, like Kikkoman Soy Sauce, is made using the traditional honjozo process. It starts with just four ingredients: soybeans, wheat, salt, and water, plus a bit of help from the koji mold.
Soy sauce has been made this way in Japan for centuries.
Making the koji.
Steamed soybeans and roasted, crushed wheat are blended, and a koji mold (Aspergillus) is added. Our special Kikkoman Aspergillus, used since the company was founded, is the key to the characteristic flavor of Kikkoman Soy Sauce. Over three days, the mold produces enzymes that break down proteins and starches during fermentation.
Brewing the moromi.
The koji is mixed with saltwater brine in fermentation tanks to create a mash called moromi. Over several months, lactic acid bacteria and yeasts slowly transform the moromi. They break proteins into amino acids, which creates soy sauce’s signature umami flavors. Fermentation also converts starches into sugars and alcohols and generates more than 300 aroma compounds.
Pressing and refining.
The mature moromi is layered into cloths and pressed slowly to extract the raw soy sauce. After settling for several days, the clear, reddish-brown liquid is heated to halt fermentation and lock in flavor before bottling.
How chemical soy sauce is made
Chemical soy sauce manufacturers use modern food science and industrial processing to make a product that has some of the features of fermented soy sauce. It doesn’t rely on the koji mold, uses a longer list of ingredients, and can be ready to ship in days instead of months.
- Acid hydrolysis. Instead of fermenting whole soybeans, manufacturers boil defatted soy meal in hydrochloric acid for many hours. The acid breaks down the soy proteins into amino acids.
- Neutralization and filtration. The acidic mixture is cooled and neutralized with sodium carbonate or sodium hydroxide, then filtered to remove impurities. The resulting liquid is called hydrolyzed vegetable protein (HVP).
- Coloring and flavoring. Because HVP on its own lacks the color, aroma, and flavor of traditionally brewed soy sauce, manufacturers add ingredients like caramel color, corn syrup, and salt. The finished product is then packaged and ready to sell.
Chemical soy sauce has a strong but flat saltiness that lacks the depth of a fermented sauce because acid hydrolysis breaks down nearly all the soy proteins into amino acids.
Flavor, aroma, and color compared
| Traditionally Brewed Soy Sauce | Chemical Soy Sauce | |
|---|---|---|
| Flavor | A balanced blend of salty, sweet, and sour notes layered with deep umami. | Mostly salty with a one-dimensional taste. |
| Aroma | Rich and layered, with hints of fruit and roasted grain. The bouquet develops naturally as hundreds of volatile compounds form during fermentation. | Sharp and flat, with a chemical edge. Because no fermentation occurs, the esters, alcohols, and other volatile compounds responsible for a developed aroma are absent. |
| Color | A clear, reddish-brown that lets light pass through. | Typically darker and more opaque. The color comes primarily from added caramel coloring. |
| Texture | Smooth and fluid, with a clean, light consistency that coats food evenly without clinging. | Often thicker or stickier due to added corn syrup and other thickening ingredients. |
| Aftertaste | A pleasant, lingering umami that fades gradually and complements the food it seasons. | Can leave a sharp, metallic, or overly salty aftertaste. |
How to tell the difference at the store
It’s easy to taste and smell the difference between chemical soy sauce and traditionally brewed soy sauce, but what about when you’re picking some up at the store? The label tells you everything you need to know.
Look for the words “traditionally brewed”
Soy sauces made through traditional fermentation will say “traditionally brewed” on the label. If you don’t see that or a similar phrase, the product was likely made using acid hydrolysis or a blend of chemical and brewed soy sauce.
Check the ingredient list
Kikkoman Soy Sauce has a short, simple ingredient list: water, soybeans, wheat, and salt. Chemical soy sauce typically lists hydrolyzed soy protein or hydrolyzed vegetable protein, along with additives like caramel color, corn syrup, and preservatives.
Traditionally brewed soy sauce from Kikkoman
Kikkoman Soy Sauce is traditionally brewed using the honjozo process for unbeatable flavor and complexity. If you’d prefer a low-sodium alternative, try Kikkoman Less Sodium Soy Sauce, which is traditionally brewed to retain the same richness.
You can also explore the full range of Kikkoman Soy Sauces, including Organic Soy Sauce and Tamari Soy Sauce.
