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Ingredient Guide

A Guide To Soy Sauce

28 April 2022

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Everything you need to know about one of the oldest condiments in the world

What is soy sauce?

Soy sauce is a staple in Asian cuisine and one of the oldest condiments on the planet. It originated in China over 2,500 years ago and was introduced to Japan in the seventh century. Today it’s used widely, both as a condiment and cooking ingredient across the world, adding a distinct taste to a variety of dishes, like noodles, rice and sushi. It comes in a number of different varieties, from light to dark and thick to runny and the majority of soy sauces found on supermarket shelves are either Chinese or Japanese.

How does soy sauce get its rich brown colour?

The gorgeous reddish-brown colour of soy sauce is the result of the Maillard Reaction, which begins two or three months after brewing starts. In this reaction the sugars of the soy sauce combine with amino acids to produce melanoidin, a brown pigment which gives soy sauce its beautiful rich colour.

How is soy sauce made?

There are various ways to make soy sauce, but traditionally it’s made using five main ingredients: soybeans, wheat, water, salt and yeast. And although there are many types, many of them share the same manufacturing process, which can take months, or in the case of very high-quality artisanal varieties, even years. In the traditional brewing method, soybeans are cleaned and soaked, then steamed and mixed with a yeast culture and wheat flour, before being fermented using a process called hydrolyzation, which breaks them down using acid. This releases sugars and helps develop soy sauce’s recognisable rich brown colour. Similar to wine, the longer it ages, or ferments, the more complex and deeper the flavour.

To speed up the manufacturing of soy sauce and meet demand, newer methods were invented which don’t involve any fermentation – cutting down the production time from months, to just a few days. This modern-day (non-brewed) method is known as acid hydrolysis, where soybeans are heated to 176°F (80°C) and mixed with hydrochloric acid. This process breaks down the proteins in the soybeans and wheat and is believed to produce a more consistent product with a longer shelf life. However, traditionalists argue that this chemical method doesn’t give the same depth of flavour and aroma as fermentation, which is why additives, like caramel, corn syrup, salt and lactic acid are added to enhance the flavour and darken the colour.

What does soy sauce taste like?

The taste of soy sauce can differ depending on the variety and type of cuisine, but generally it offers a salty, sweet, umami (savoury) flavour to dishes.

Is soy sauce gluten-free?

Given its name, many people may assume that soy sauce is gluten free. But as most soy sauce recipes are usually made with wheat flour, people who are allergic or intolerant to gluten need to buy gluten-free or wheat-free versions, like tamari, a Japanese version of soy sauce that’s traditionally made without wheat. Kikkoman, a major Japanese food manufacturer famous for its soy and teriyaki sauces, makes several gluten-free products, including a tamari-style soy sauce that only uses water, soybeans, rice and salt. It can be found in a number of UK supermarkets, just look out for a bottle with a gluten-free label. 

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What are the different types of soy sauce?

Many people think there are just two different types of soy sauce, light and dark. But in fact, there are hundreds of different varieties. Chinese soy sauce is very different from Japanese soy sauce, and both of these have varieties within each too. Here, we’ll guide you through the differences between Chinese and Japanese soy sauces, the varieties within each style and how to use each one.

Chinese soy sauce

There are three types of Chinese soy sauce: light, dark and regular. Light and dark refer to the colour of the sauce and have nothing to do with salt content. 

Light soy sauce

If you see a Chinese recipe that simply says ‘soy sauce’, unless it specifies which style, you’re best off using light soy sauce. It has a pungent aroma, amber-gold colour and delicate but salty flavour. Light soy sauce is a staple seasoning, light salt and pepper, that’s used to enrich Chinese sauces and marinades. It’s best used in dishes where you don’t want to add too much colour. It’s commonly used in Chow Mein and stir-fries, adding flavour to Chinese soup broths and also as a dipping sauce for dumplings.

Dark soy sauce

Dark soy sauce is more intense in flavour than light soy sauce. Even though it contains more salt, light soy sauce actually tastes saltier. This is because the flavour of dark soy sauce overpowers its saltiness. It’s also sweeter and thicker, due to the addition of sugar or molasses. Dark soy sauce is typically used in the later stages of cooking to season and colour a dish, giving it a gorgeous caramel colour – you only need a teaspoon or two to take a dish from pale to amber brown. Dark soy sauce in Chinese cuisine is mainly used for cooking (not dipping like light soy sauce) with braised red-cooked meats like pork, or to give meat stir-fries like beef and broccoli a wonderful mahogany stain.

Thick soy sauce

Thick soy sauce is made with sugar and therefore sweeter than dark soy sauce, and it also has a thicker consistency. It’s often used for longer cooking methods, stir-fries and dips. In Tawainese cooking you’ll find it in stews and braised pork rice. 

Japanese soy sauce

Japanese soy sauce (or shoyu) is used to enhance the flavour of almost any dish and it’s clearer, thinner and less salty than its Chinese counterpart. It’s made with toasted wheat, while Chinese soy sauce is usually made with wheat flour.  There are two main types: dark soy sauce (koikuchi shoyu) and light (usukuchi shoyu), but there are also other varieties including Tamari.

Dark soy sauce  (koikuchi shoyu)

Dark soy sauce is used in everyday Japanese cooking – in marinades, sauces, braising liquids and stir-fries. If a Japanese recipe calls for soy sauce and doesn’t specify a type, you should use koikuchi.

Light soy sauce (usukuchi shoyu)

The Japanese generally use light soy sauce sparingly. It’s thinner, milder and lighter than dark soy sauce with a saltier, rich umami flavour, seasoning foods without changing the colour. It’s perfect for delicate sauces and  lighter dishes, like Tamagoyaki (a Japanese omelette that’s made by rolling together thin layers of fried and seasoned beaten eggs), in broths and everyday stir-fries. 


Tamari is dark, thick and less salty. It’s made from fermented soybeans and unlike traditional soy sauce contains little or no wheat, which is why it’s often used as a gluten-free alternative. It originated as a liquid byproduct of miso (a traditional Japanese paste), which gives it its rich, full-bodied umami flavour. Due to its high soybean content, tamari has a stronger flavour and thicker texture (similar to hoisin), with hints of caramel. It’s generally used as a marinade or dipping sauce for sashimi and sushi and as a finishing seasoning for soups and stews. It also makes a good sauce for grilled meat and as a flavour enhancer for tofu and fried rice. It can be used as a substitute for soy sauce and is loved by health enthusiasts as it tends to be free from the additives, like MSG (mono sodium glutamate) that are usually added to soy sauce.

Is soy sauce vegan?

If you’re vegan, you’ll be delighted to hear that you can enjoy soy sauce, because it’s entirely plant-based. However, in some modern-day production methods flavour enhancers are added, like E627, which is often sourced from fish – therefore making it non-vegan. So if in doubt, it’s always best to check the label, or stick to a traditional soy sauce that just contains the basic five ingredients.

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Is soy sauce bad for you?

Although traditional soy sauce is low in calories (1 tablespoon contains 11 calories) and carbs, it’s incredibly high in sodium. A single tablespoon contains over 900mg, which is more than a third of your daily salt allowance – and more salty than a Mcdonald’s Big Mac. It’s also believed to impact the effect of medication on people suffering from hyperthyroidism. But it isn’t all bad news. Soy sauce is rich in antioxidants and has some potential health benefits, such as supporting healthy digestion, reducing allergic reactions, including inflammation, boosting the immune system and lowering blood pressure. So in a nutshell, like most foods, you can enjoy soy sauce in moderation as part of a healthy diet – it’s all about how you use it.

Did you know? A study by the National University of Singapore revealed that Chinese dark soy sauce contains 10 times the antioxidants of red wine, and can help prevent cardiovascular diseases

Where to buy soy sauce

You can find well-known brands of soy sauce, like Kikkoman and Amoy, in most supermarkets, but if you’re looking for the high-end, authentic varieties you’re best off looking in Asian grocery stores or online.

How to store soy sauce

Unopened soy sauce should be kept in a cool, dark place. After opening, it should be stored in the fridge to extend its flavour and freshness, and consumed within a year.

Substitutes for soy sauce

Liquid aminos, like Bragg, are commonly used as a healthier alternative to soy sauce and tamari. They’re made from soybeans, but unlike soy sauce they don’t contain wheat, making them naturally gluten-free and therefore a great alternative for those who have intolerances and allergies. Liquid aminos are less salty, milder and taste slightly sweeter than soy sauce, and are closest in flavour to light soy.

Similar to liquid aminos, coconut aminos are another popular, gluten-free alternative to soy sauce. Made from fermented coconut sap, they offer the same umami flavour and dark colour as soy sauce, but are slightly sweeter. They’re also lower in sodium.

As mentioned earlier in this blog, some tamari is gluten-free but not all, so if you want to use this as a substitute make sure you check the label if you’re sensitive or intolerant to gluten. It’s the closest in taste to soy sauce because it’s made and fermented in a similar way, but has a darker colour and slightly less salty flavour. You can replace soy sauce with tamari using the same quantities.

Some refer to Worcestershire sauce as soy sauce’s cousin. A fermented liquid condiment (just like soy sauce), it’s sweet and tangy with a powerful umami flavour. Worcestershire sauce includes a lot more ingredients than soy sauce, including anchovies, onions and vinegar, which also contributes to its rich taste. But because it’s quite strong, when substituting just use a little at a time so you don’t overpower your dish.