Clearspring Organic Tamari is one of the few wheat-free soya sauces in Japan still brewed to the original 500 year-old recipe.

Inside the kura, or storehouse, at the brewery on the Chita peninsula of Aichi, rows of giant hundred-year-old cedarwood kegs are filled with thick, rich tamari. The air is full of the heady aroma of fermenting soya sauce and, if you listen carefully, you can hear the sound of the bubbling brew, particularly on hot summer nights.

Fourth-generation brewery president, Yoshio Aoki, still uses the traditional recipe and techniques of his forebears: organic whole ingredients, hand-made soya bean koji, a high ratio of soya beans to water, and long, natural cedarwood ageing.

In the autumn, when conditions are ideal for making koji, the Aoki family begin each day by soaking the organic soybeans in well water. The next day, the swollen beans are steamed and then crushed into tiny balls called miso-dama. These balls are dusted with a mixture of Aspergillus spores and roasted barley flour and then placed in the koji room to incubate for about three days. During this delicate process, the temperature and humidity are carefully controlled.

The sweet smelling, fluffy, pale yellow balls, now called koji, that emerge from the koji room are placed on bamboo mats to dry for two weeks. No other company uses this unique koji drying process which it is claimed is responsible for creating the unique double-strength quality of Clearspring's tamari soya sauce.

The dried koji is mixed with a sea salt and water solution and placed in the giant cedarwood kegs to ferment. The fermenting mash, called moromi, is topped with large river-washed stones.

During the long ageing process, enzymes from the koji culture together with naturally occurring yeasts and bacteria slowly break down the moromi mash. The complex carbohydrates, proteins, and oils of the soya beans are transformed into natural sugars, aromatic alcohol, and flavourful amino and fatty acids.

The mature fermented moromi is then placed in cotton sacks and pressed to extract the dark liquid, a mixture of tamari and waxy oil residues. The waxy residues, which rise to the surface, are removed and the tamari is pasteurised to prevent further fermentation, and stored ready for distribution and bottling.

Shoyu, which contains wheat, will naturally develop some alcohol during fermentation which acts as a preservative, but wheat-free tamari does not develop enough alcohol naturally, so most tamari breweries routinely add refined alcohol as a preservative. The Aoki family, however, add a small amount of Mikawa mirin (organic rice liqueur) added, instead, to stabilise it.

The entire brewing process for Clearspring Organic Tamari soya sauce takes about eighteen months.

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