Soy sauce is a brown liquid with a salty, peculiarly meaty flavour that is used as a savoury condiment in Oriental cuisine.
The Japanese term koji refers to a foodstuff intentionally overgrown with fungi or other micro organisms, causing proteins and other elements within it to be degraded in certain ways. The growth of Buddhism during the 6th Century had made meat eating unpopular in Japan and China and so salty grain pastes, fermented as koji, were used as an alternative to meat. In the 13th Century, a Zen Buddhist monk called Kakushin discovered such a delicacy based on soybean paste while he was studying in China and brought the idea home to Japan. This paste, called miso, generated a thick dark liquor when left for a time, and this was the first soy sauce. Its equivalent today is the very dark tamari variety.
The production process later evolved to include the addition of wheat to the soybean paste and acquired a brewing stage so that by the 16th Century shoyu, or the modern soy sauce, was being made. Over the following centuries it has become an increasingly industrial process so that in the present day it is continuous and mechanised, and the product is far more consistent.
In small scale production, soybeans are soaked, cooked, coated with ground wheat and left on trays to become mouldy with a filamentous fungus called Aspergillus oryzae, the growth of which should be promoted by these conditions. When the koji has matured it is mashed and added to salted water. This is brewed in an airtight container. In modern industrial production, the soybean-wheat mash is mixed continuously so that mould growth is more evenly distributed through it and the brewing process involves the addition of two further micro organisms. After brewing for several months, the liquid is filtered, pasteurised and bottled.
The Qualities of Soy Sauce
Soy sauce is used throughout Oriental cooking to flavour meat and vegetables, often as part of a marinade, and also as a table condiment. Most of the soy sauce consumed in the world today is dark soy sauce, or koikuchi. However, lighter varieties such as usukuchi are also produced by varying elements of the same basic production process and these are particularly used to accompany, for example, white meats and fish. Popular in Chinese cuisine is a black variety that is sweet and sticky due to the addition of molasses into the brew.
The unusual flavour of soy sauce is apparently due to the presence of amino acids resulting from the breakdown of soybean proteins by the fungi in the koji. This, and the saltiness of soy sauce, allows it to bring out the flavours of food that it accompanies, making it an indispensable and versatile condiment.