While there are a number of well-established soy sauce manufacturers in Japan, Marunaka Shoyu is one of the few remaining breweries still dependent on traditional practices and instruments. For this reason, the breweries of Marunaka Shoyu have been recognized by the Japanese government as a National Tangible Cultural Property.
The production of soy sauce at Marunaka Shoyu is a methodical, three year ordeal, during which time artisan brewers are involved on a daily basis. In the absence of modern monitoring equipment, brewers are challenged to keep the process moving forward, relying upon their senses and experience to direct the operation.
Koji is the Japanese term referring to the mix of microorganisms essential to the brewing of soy sauce. For generations, these koji have lived in the wooden vats at the Marunaka Shoyu brewery, being cared for by the brewers, untouched by artificial methods or manipulation. Each wooden vat contains a unique blend of koji, differing from that of the neighboring vats. Only through the blending of the individual batches is Marunaka Shoyu's true flavor established.
The area around Marunaka shoyu, was sandwiched between the Suzuka Mountains and the Lake Biwa, in the east of Shiga prefecture, middle of the Japan.
The climate has played a large role in naturally shaping the unique blend of koji used at Marunaka Shoyu, because the presence of nearby the lake helps provide a humid environment to the region and, in winter, it makes a heavy snowfall which create the conditions for a successful brewing process.
It requires time for aging to produce the real soy sauce. So our product is tasteful even adding some water with a little salt. And the Marunaka may have different variations of tastes and aromas of the sauce, without the professional mix technique that has been required for the same taste and color.
Anyway, it is all that Marunaka Shoyu's production relies three important phases for over 200 years.
A brine-processing method unique to Marunaka Shoyu, shiotsuri is not used anywhere else in Japan.
During this process, hemp bags filled with salt are placed within wooden vats containing water, allowing the salt to dissolve slowly over time. Shiotsuri, which literally means "salt hanging", gradually increases the salt content of the water, activating the koji living in the vats and readying them for the next phase.
After shiotsuri is completed, the process of kaiire is carried out for nearly three years.
During this period, brewers rely heavily on their skill and knowledge of the craft, constantly interracting with the product to control the temperature and fermentation process.
Through the use of a kaibou, brewers carefully blend the moromi, or mixture of soybeans, wheat and salt, within the wooden vats. As the koji contained in the vats begin interacting with the moromi, brewers closely monitor the fermentation process to ensure consistency. Twice a day, each vat is attended to by a brewer, at which point they deftly utilize their kaibou to enliven the mixture, releasing built-up gases and reintroducing oxygen into the moromi. Throughout this stage, artisans create the ideal fermentation environment, allowing the microorganisms within the koji to thrive and flourish.
As with all processes at Marunaka Shoyu, this step is entirely reliant on the technique and experience of the brewer, and no automation or modern equipment is utilized.
Funashibori is the final step in the process, and arguably the most physically demanding of the brewers.
As the moromi is removed from the vats, hemp bags are filled with the mixture and stacked upon one another. Utilizing gravity and the compounded weight of the bags, the moromi is filtered through the hemp over the course of a week. The hemp bags, most of which have been in use for many years, filter the moromi slowly and naturally, separating the liquids from the solids. Then the bags may be put under the weight of wood and expects the drops filter in a natural way. In the finishing filtration steps, the bags are pressed by hand, removing the moromi from the final product.
The result: an exceptional shoyu unlike any other.