Seikiku (koji making)

Seikiku (koji making) is one of the key steps in sake brewing: the process of producing the koji used in brewing. It is carried out mainly in a dedicated room called a koji muro (koji room). In seikiku, koji mold is inoculated onto steamed rice, which is then kept at a controlled temperature and humidity and left to develop for several days. During this time the starches in the rice are converted into sugars, producing the koji that is essential to brewing. Koji is a major factor in determining the taste and aroma of sake, and it also plays an important role in supporting fermentation by yeast. For this reason, seikiku is regarded as a process that greatly influences the quality of sake.