Black Koji Mold

Black koji mold is mainly used in Kyushu region where there are many shochu breweries. It was discovered in 1910 in the koji mold of awamori by Gen-ichiro Kawachi, a researcher who had been searching for the best koji mold for shochu. In those days, yellow koji mold was used for making shochu just like sake. However, as yellow koji mold is sensitive to heat, it can easily sour in warmer region as Kyushu. So, Mr. Kawachi had been researching on koji mold of awamori, known as the distinctive sake of Okinawa, the region even hotter than Kyushu. His achievements have earned him the reputation as the “father of modern shochu”. The scientific name is Aspergillus luchuensis and luchuensis comes from Ryukyu, another name for Okinawa.
The feature of black koji mold is that it contains plenty of citric acid, found in lemons, etc. Citric acid, which inhibits the growth of bacteria, makes it possible to brew sake safely even in hot and humid regions. The charms of shochu using black koji mold are the acid taste created by citric acid and the sharp taste. It came to be called haikara (meaning stylish) shochu to be spread across Kyushu.
Yet for sake brewing, black koji mold was rarely used, because it is too acidic and leaves an undesirable odd flavor and astringency in the pigments. However, in recent years, with the advancement of research in the sake brewing industry, sakes that bring the best of rice’s savory taste and black koji mold’s distinctive acid taste have been released one after another. More and more breweries are now working on new flavors of sake using black koji mold.