It Gives the Rice a Kick: Sweetness and Kōji in Early Modern Sake Brewing

The mold kōji (Aspergillus oryzae) contributes to the sweetness of sake and plays a vital role in alcoholic fermentation and in the creation of Japanese foodstuffs like miso and soy sauce. While scientists are uncovering kōji’s genetic past, the mold’s history is also told in the records of early modern (1600–1868) sake brewers, who may not have understood they were using microorganisms but managed to develop sophisticated means of cultivating the filamentous fungus and comprehended well its impact on the taste of their beverages. A section from The Idiot’s Guide to Sake Brewing (Dōmō shuzōki), completed in 1688 and translated here, offers the oldest discussion of how brewers worked with kōji in Japan. When viewed in the context of earlier references, it shows that kōji’s role as a sweetener was historically secondary to its primary function to facilitate alcoholic fermentation.