1Soy sauce is a staple of Asian cuisine, used as both a condiment and cooking ingredient.
2Its roots are in the seasonings of ancient China.
3Today you can buy artificial or chemically enhanced versions,
4but authentic soy sauce is all natural and made the traditional way, by brewing soybeans and wheat.
5At this small soy sauce company, they use the centuries-old slow fermentation method and just five ingredients.
6Soybeans, water, wheat, sea salt and yeast.
7They begin by pouring soybeans into a cooking device called a steam kettle.
8After thoroughly rinsing the soybeans twice, they fill the kettle with water.
9They close the lid and boil the beans for four hours.
10Meanwhile, they pan-roast wheat in a skillet for 25 minutes.
11Then they put the roasted wheat through a mill.
12The mill's steel rollers crack each grain into several pieces.
13This will enable the yeast to better penetrate the wheat during the fermentation process.
14When the soybeans are ready, they take them out of the kettle and spread them out in large trays to cool.
15When the beans cool to 33 degrees Celsius, it's time to add the wheat.
16After mixing everything thoroughly, they sprinkle on yeast and mix again.
17The ingredient proportions are key, which means it's a company secret.
18To activate the yeast, they transfer the mix to shallow boxes and stack them for about 48 hours in a controlled incubation room.
19This process generates heat, which rises,
20so they have to gradually move boxes to lower racks, preventing overheating, which would kill the yeast.
21For the next stage, they make a brine by mixing fine sea salt with spring water.
22To give its soy sauce a distinctive taste,
23this company reuses bourbon barrels from local distilleries to act as fermentation vessels.
24Traces of bourbon in the wood permeate the mix as it ferments,
25infusing the sauce with a subtle smoky and sweet flavour.
26After dissolving the sea salt in the spring water, they add the soybean mix,
27creating a moromi, the Japanese word for soybean mash.
28They blend for a few minutes, then seal the barrel and leave it to ferment.
29Once a day for the first six weeks, they open the barrel and mix the moromi to aerate the gases that build up.
30This keeps the yeast active and helps develop the flavour.
31Then after that, they open and mix just once a week.
32After 12 months of fermentation, it's finally ready.
33They open the barrel and mix one last time.
34Then they empty the barrel onto a sheet of muslin, lining the tub of a stainless steel press.
35They fold over the sheet to enclose the moromi.
36Then they lay down planks of wood to form a solid, flat surface.
37This press applies six tons of pressure, forcing the planks downward against the moromi.
38This squeezes out all the liquid, which is the soy sauce.
39It drains out through a hose at the base and then moves on to be filtered and heat pasteurized.
40The pressed moromi gets a new life as high-protein animal feed.
41While many soy sauces are mass-produced, this factory brews small batches at a time.
42A batch yields about 600 bottles, each of which are filled manually.
43They top each bottle with a plastic diffuser, which allows just a dash of sauce at a time.
44Then they twist on a plastic cap and slip a shrinkable plastic band over it.
45Using a heat gun, they seal the band tightly around the cap and bottle,
46then the label on which they write the batch code and bottle number by hand.
47A fitting finale for this signature soy sauce.
48Very tasteful.