Soy sauce originated in China 2500 years ago, spreading to East and Southeast Asia, it’s made from fermented soy beans, wheat flour, water, and salt.
Chinese soy sauce is primarily made from soybeans, with relatively low amounts of other grains. There are two main varieties:
1. Light soy sauce or fresh soy sauce: A thin (non-viscous), opaque, lighter brown soy sauce. It is the main soy sauce used for seasoning since it is saltier, less colourfully noticeable (due to its lighter colour), and also adds a distinct flavour. The light soy sauce made from the first pressing of the soybeans is called TóuChōu, which can be loosely translated as first soy sauce or referred to as premium light soy sauce. Touchōu is sold at a premium because, like extra virgin olive oil, the flavor of the first pressing is considered superior.
2. Dark soy sauce or old soy sauce, a darker and slightly thicker soy sauce, is aged longer and contains added molasses to give it its distinctive appearance. This variety is mainly used during cooking since its flavour develops during heating. It has a richer, slightly sweeter, and less salty flavour than light soy sauce. Dark soy sauce is partly used to add color and flavour to a dish after cooking, but, as stated above, is more often used during the cooking process, rather than after.
In traditional Chinese cooking, these soy sauces were employed in strategic ways to achieve a flavour and colour for the dish. By the way, store soy sauce at room temperature.