Light soy sauce and dark soy sauce are two varieties of the same soy-based seasoning. They have different properties and different applications in some parts of Asia but have some of the same umami flavor notes in common. How different are light and dark soy sauce? Can you use one as a substitute for the other? We will provide answers to these questions and more in this SPICEography Showdown.
How does light soy sauce differ from dark soy sauce?
The most obvious difference between light and dark soy sauce is indicated by the name. Light soy sauce has a lighter color than dark soy sauce. Light soy sauce is a translucent brown similar to coffee; dark soy sauce is opaque and almost black. It is closer in color to molasses.
Light soy sauce is thin and watery while dark soy sauce is thicker and more viscous. An easy way to demonstrate the difference is to shake the bottle. When you shake a bottle of light soy sauce, it will quickly run off the inner surface at the top of the bottle leaving it clear; when you shake a bottle of dark soy sauce, it will coat the inner surface. Dark soy sauce is used as much for its ability to add color as for its flavor benefits.
Flavor is another important area where they differ. Light soy sauce is the saltier of the two; dark soy sauce has a sweeter taste with molasses notes. The taste of light soy sauce is described as being more refreshing; in comparison, dark soy sauce is said to have a bolder and heavier flavor.
If your recipe calls for one, can you use the other?
Neither soy sauce is ideal as a substitute for the other, but they can work if you have no other options. If you need to use light soy sauce as a substitute for dark, add a 1/8 teaspoon of white sugar to each tablespoon of light soy sauce to simulate the sweetness of dark soy sauce. You can use extra reduction and deeper caramelization in the dish to replicate the browning effect that dark soy sauce would bring.
Similarly, dark soy sauce can work as a substitute for light soy sauce but you will need to make changes. Add a small amount of water to your soy sauce to thin it out. You should also add 1/8 teaspoon of table salt or MSG to compensate for reduced saltiness. You will need to be careful when using dark soy sauce because it can make food slightly bitter if you use too much of it. It can also give dishes an excessively dark color.
When should you use light soy sauce and when should you use dark soy sauce?
Use light soy sauce in dipping sauces and sauces for stir-fries. It is commonly used in Cantonese cuisine. If a recipe for a Cantonese dish calls for soy sauce, you need to use light soy sauce.
Use dark soy sauce for braising and stewing. It’s used in dishes like red cooked pork or to give a brown color to beef and broccoli or fried rice. Many Chinese and Thai recipes call for some of each so that both sets of benefits are brought to the dish.