【Storage】 
Avoid moisture. Once opened, keep it in an air-tight container or bag, preferably with a desiccant, and store it in a cool place or in the vegetable compartment of the fridge.

【Handling】
Please do not grow koji to propagate them. The propagation requires specialist skills. Koji makers developed the technique through their long history of operation. If you try to propagate them, the functions (each koji starters have been selectively bred to make them fit-for-purpose) and most importantly the safety can’t be guaranteed.

Koji fermentation is different to that of Kombucha making where Scoby is used to produce the next batch. In Koji making, the Tane-Koji (the starter spore) is used to produce each batch of Koji grains.

Koji being multinuclear cells, when repeatedly subcultured it becomes diploid / triploid cells which rapidly weakens active enzymes. This is why in Japan, companies specializing in making Koji spores have existed for hundreds of years.

 The production of Koji spores requires sensitive and dedicated technics. Tane-Koji manufacturers in Japan have cultivated specialized technics acquired through countless trial and error. They are able to purely separate the Koji spores that have the most active enzymes and thereby expanding those cultures. This is also why in Japan, people have been able to produce a variety of Koji fermented products such as Miso, Sake, Shoyu and Shochu with stability in quality throughout history.

 Koji is a type of mold and as we know some molds can be toxic to humans. When Koji is made without enough knowledge and skills, it can become contaminated with toxic molds. In addition, in countries outside of Japan, a type of mold called “Aspergillus Flavas” which produces strongest toxin Aflatoxin is prevalent.

 This is why, when batches of Koji are made repeatedly from “Tomo-dane” (propagation), it will eventually create something that may look similar on the outside yet essentially completely different. It has the potential of poisoning people.