All about Soy Sauce

Today, my lab mate asked me what the difference between dark soy sauce and normal sauce is. Turns out she’s never seen dark sauce before until recently! Having grown up with this condiment, I knew all about soy sauce… right?


I realized I had absolutely no idea what I was talking about. So after some solid research, I’ve learned so much more about soy sauce than I’ve ever cared to know.


First off, what is soy sauce?

It’s one of the oldest condiments in the world, with a history spanning over three-milennia. Basically, it’s fermented soybeans and wheat mixed with brine. So to start, they throw together some boiled soy beans and roasted wheat, add Aspergillus, a fungus, and let the culture sit for a few days. Afterwards, it’s combined with salt water, and lactobacillus gets added to break down the sugars into lactic acid. (Fun fact, that’s the bacteria that keeps vaginas healthy. Yum.) This mixture is then fermented over a period of time, this allows the microbes to break down the grains of soy and wheat into sugars and amino acids, before it gets filtered, pasteurized and bottled into the delicious stuff we see in stores.

Key differences in Soy Sauce

So now that we talked a little about the process of making soy sauce, you’ll notice that it’s a relatively simple recipe. So then why are there so many different kinds of soy sauces? Well, there’s a few major differences between different soy sauces

  • Soybean to Wheat ratio
  • Strains of microbes
  • Length of fermentation/aging
  • Additives

Each of these things will alter the taste a bit and each culture has their own recipes. I’m going to focus on the Chinese and Japanese soy sauces here, because they’re the most widely known soy sauce users around here.

Chinese soy sauces

These soy sauces are made primarily from soybeans only, with very little other grain. This makes them denser and saltier. There’s two major types of these you’ll see in stores: light and dark.

Light (or fresh):

  • The main soy sauce used for cooking and seasoning (if a Chinese recipe asks for just soy sauce, assume it’s this type)
  • No additional additives
  • The premium type called 頭抽, or “first sauce”, is made of the first press of the soy beans and usually more expensive
  • There’s also a double fermented type (They use soy sauce from another batch instead of brine) with a mellower, more complex flavour. These are usually used as a dipping sauce

Dark (or old):

  • Darker and slightly thicker, prolonged aging, called 老抽, or “old sauce”
  • May have added molasses, thickening agents, or other ingredients to adjust flavour
  • Richer, sweeter and less salty compared to the light version
  • Used during the cooking process since the flavours deepen with cooking time


Japanese soy sauces

The Japanese variety is called shōyu, and comes in many varieties. While Chinese soy sauces are made with only soy beans, Japanese soy sauce mix in various amounts of wheat which makes a sweeter, lighter sauce.

Koikuchi (dark):

  • The main Japanese soy sauce, if the label doesn’t specify, it’s mostly likely dark (note that this is the opposite of Chinese soy sauces)
  • Made with equal amounts of soy beans and wheat
  • Used as an all-purpose sauce, both for marinades and cooking or dipping

Usukuchi (light):

  • Lighter in colour, but saltier than Koikuchi
  • Sweeter due to the addition of mirin, a sweet rice wine
  • Can be used to replace the dark version but sparingly due to the intense flavour

Tamari (soybean only):

  • Most similar to Chinese soy sauce, has little to no wheat
  • Stronger flavour, usually used as a dipping sauce
  • Was traditionally the liquid byproduct during miso fermentation (Another seasoning made of fermented soybeans)



That’s the basics of soy sauce, especially the ones you’ll see at the supermarket. Although there are so many types of soy sauce, the average home cook probably wouldn’t go wrong with any of them. The best thing to do is to try them all to see which ones you like the most, and in what dish. And reading the ingredients list will help you determine which ones are better. (Stay away from the chemical stuff made of hydrolyzed soy protein, they won’t taste as good as the traditional)


Soy sauce is a condiment used for marinades, cooking, or dipping sauce.

Chinese soy sauces (ex. Lee Kum Kee): Light is the regular. Dark is thicker, sweeter and has additional ingredients

Japanese soy sauces (ex. Kikkoman): Dark is regular/all-purpose. Light is thinner but has more intense flavor (both sweeter and saltier).






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