Of the three qualities of soya sauce you can find on shop shelves, Clearspring traditionally craft-made soya sauce is the highest quality available. The other two qualities are naturally brewed soya sauce and non-brewed soya sauce.
This is how each quality is produced:
All Clearspring soya sauces, regardless of whether they are labelled simply as soya sauce or they use the traditional Japanese names of shoyu (with wheat) or tamari (wheat-free) soya sauce, are made to traditional craft-made standards, and as such are some of the very best soya sauces available anywhere in the world.
Craft-made soya sauce is still produced using centuries-old Japanese recipes, in which whole cooked soya beans and roasted cracked wheat are used, and the koji inoculation (with cultured mould spores) is carried out over the traditional three days followed by lengthy maturing in cedarwood kegs over 15 months at the ambient seasonal temperature. Pressing sacks are wrapped by hand, and the entire process is carried out without the use of chemicals. Clearspring is committed to using non GM soya beans and where possible organically grown ingredients. Less than 1% of soya sauce in Japan is still made to these standards.
The long, slow ageing in decades-old wooden kegs enhances the fermentation process and draws out natural glutamic acid to ensure a rich savoury aroma and a complex sweet/savoury taste that is highly prized amongst connoisseurs. The end result is a seasoning sauce in which the soya bean's basic elements have been transformed into more digestible nutrients. Clearspring miso is made by a similar traditional method.
Most soya sauce is not made the traditional way any more, however, and the next best quality is so-called naturally brewed soya sauce, which is made by a few large companies in Japan, the EU and USA.
Production follows a similar method to traditional craft-made soya sauce with cooked soya and roasted cracked wheat being inoculated with koji and then fermented with salt followed by pressing the mash to squeeze out the liquid soya sauce.
What is not so natural, though, is the speeding up of the process by using de-fatted soya protein meal rather than whole soya beans. This meal is the product of the industrial crushing process that the vast majority of the world's soya beans go through. The raw beans are broken down to thin flakes, which are then percolated with a petroleum-based hexane solvent to extract the soya oil. The remaining meal is the base for soya sauce and other soya foods.
Another point of difference with traditional soya sauce production is the use of automated koji production followed by accelerated ageing at high temperatures in steel or plastic tanks for only three to six months.
Most major Japanese brands of soya sauce, labelled as naturally brewed, are made by this method.
Although lacking the subtle nuances of flavour and digestion-enhancing properties of traditional craft-made soya sauce, naturally brewed soya sauces do have a fuller flavour and a less overpowering taste than the most basic grade, non-brewed soya sauce.
Non-brewed Asian-style soya sauce (commonly labelled - soy sauce) is quite different. Although usually vegetarian, it has a strong meat-like flavour and depending on the recipe is called either dark or light soya sauce. This is the soya sauce that you are most likely to find on your supermarket or corner shop shelf.
It is mass produced quickly and cheaply all over the world by a modern process that has little in common with traditional Japanese soya sauce production. De-fatted soya flour is mixed with hydrochloric acid at high temperature under pressure to create hydrolysed vegetable protein (HVP). Salt, caramel and chemical preservatives and flavourings are then added to provide colour and taste.
This method, known as rapid hydrolysis, uses the enzyme glutamase as a reactor and creates large amounts of the unnatural form of glutamate that is found in MSG.
In 2001 the UK Food Standards Agency (FSA) highlighted the dangers of some non-brewed soya sauce brands developing high levels of the toxic chemical 3-MCPD.