From soy sauce to sake, miso and vinegar, fermentation is the driving force behind many of Japan’s most famed culinary treasures. Indeed, it is rare to encounter a traditional Japanese meal that does not include some kind of fermented ingredient or dish.

Fermentation is a complex process whereby microorganisms break down sugars and other carbohydrates into organic acids, alcohol and proteins. Although this can occur naturally without outside intervention, human beings have been learning ways to nudge nature in the desired direction since the dawn of civilization.

In modern-day Japan, large manufacturers typically rely on additives and artificially controlled temperatures to mass-produce fermented foods quickly and cheaply. Meanwhile, a small number of producers continue to emphasize quality ingredients, hard-earned knowhow, and time-honored techniques to create traditional fermented foods of superior quality.

The video above shows fermentation in action. In the storehouse of a traditional soy sauce manufacturer, microorganisms energized by the hot summer weather break down a fermenting mash of soybeans and wheat called moromi, releasing bubbles of CO2 to the surface.

While most producers now use steel tanks to make soy sauce, this company is one of just a few artisanal brewers that continue to use cedar casks. The wooden casks and walls of the storehouse contain their own ecosystem of microorganisms, which give the soy sauce its unique flavor and aroma.