Have you visited a Soya Sauce plant? It is important to understand how Soya Sauce is made for us to know how to choose a healthier version of soya sauce. Soya Sauce making has two methods, traditionally brewed method, and the chemical method.
Process of Making Traditional Soya Sauce
Soya Beans are washed and boiled in a big pot. After the beans are cooked, the cooking liquid is saved for further fermentation. High in protein, this liquid adds great flavour to the soya sauce.
After cooling, flour is added to the beans to dry them by drawing out moisture, allowing the mould to grow better; secondly, the flour contains carbohydrates that the bacteria feed on to break down the chemical structure of the beans. The soya beans are placed on trays to start the fermentation process as shown in the picture below.
After 4 to 5 days, the soya beans are ready to be moved into larger tanks filled with brine or saltwater for a longer fermentation.
These sauces are kept for at least three months and sometimes up to a year, in their respective tanks, where nature does the hard work of fermentation.
The chemical method is by hydrolysis where soya sauce can be produced in just 2 days!
This process starts with the soya beans being boiled in hydrochloric acid for 15 to 20 hours, to break down the soy protein into amino acids. Once maximum hydrolysis is reached, the mixture is cooled to stop the conversion process. The amino acids are then neutralized by adding sodium carbonate. The liquid is then filtered, mixed with active carbon, and purified to produce a hydrolyzed vegetable protein (HVP).
This HVP has none of the flavour found in a naturally brewed soya sauce as it contains low levels of glutamate acid. Wheat gluten is added to boost the glutamate levels. Caramel, colouring and corn syrup is also added to give sweetness and colour.
The chemical hydrolysis process also produces byproducts such as hydrogen and dimethyl sulphide that emit strong smells. Another byproduct is a carcinogenic chemical compound known as 3-MCPD (3-monochloropropane-1,2-diol). The manufacturing process for acid-hydrolyzed protein can be modified to reduce the levels of 3-MCPD, but cannot completely eliminate them. You can also check the labels for anything that says ”soy protein extract”.