It starts on the left with the three main ingredients:
- 麦 mugi 'wheat or barley', which you roast (煎る iru [also written 炒る]) and crack (ひきわる hikiwaru [or 砕く kudaku 'crush']}
- 豆 mame '[soy]bean' (大豆 daizu lit. 'big-bean'), which you steam (蒸す musu)
- 種麴 tanekouji (lit. 'seed-malt') 'malt starter (Aspergillus bacilli)'
Add malt to brine (塩水 shiomizu/ensui 'salt-water') while stirring with a paddle (櫂 kai) to make a mash (もろみ moromi).
After it reaches maturity (熟成 jukusei), press it (しぼる shiboru) to separate the liquid raw shoyu (生醤油 kijouyu, namashouyu) from the raw dregs (生揚 kiage, namaage).
The raw shoyu is heated (火入 hiire 'fire-insert') (pasteurized) to make regular refined shoyu (醤油).
The solid dregs have many other uses. In 1781, a brewer in Yanai combined the dregs (instead of brine) with a new batch of malt to make Yanai's trademark 甘露醤油 Kanro Shouyu lit. 'sweet-dew shoyu', more prosaically known as 再仕込み醤油 sai-shikomi shouyu 'refermented shoyu', which has a lighter taste (淡口 usukuchi) especially suitable for delicate sashimi. This process is outlined in the bottom line of the chart above. (The Sagawa shop offers small spray bottles of Sweet Dew soy sauce.)
The Kikkoman Institute for International Food Culture publishes an English-language bulletin called Food Culture that contains an interesting series of articles by food historian Ryoichi Iino on the History of Shoyu.
1. Origins of fermented sho (Ch. jiang) in China and use in Heian Japan
2. Use of sho in Heian and Kamakura periods, decline of liquid sho in favor of miso
3. Uses of miso and rise of shoyu and tamari in pre-Edo Period
4. Production and diffusion of shoyu in the Edo Period