Growth evaluation The solid-state plates used in this study were prepared
with barley, non-waxy rice (japonica rice), or waxy rice according to the following
procedure. Each material was ground in a blender (Osaka Chemical Co. Ltd., Osaka,
Japan), and the resultant powder (10 g) was mixed with 18 ml of deionized water in a
glass dish and autoclaved. Starch in the raw material was then gelatinized to form the
final culture plate (solid-state plate). M. anka was grown on potato dextrose agar (PDA)
at 40 °C, and its spores were harvested and suspended in sterile water. The solid-state
plates containing the respective raw materials were inoculated at their center with
approximately 1 × 102 spores. To evaluate the growth of M. anka on the solid-state
plates, the area of the mycelial colonies was measured every day. To evaluate the
mycelial content in red koji, the N-acetyl-D-glucosamine (NAG) content of dry red koji
was measured by using a rice koji-measuring kit (Kikkoman Corp., Chiba, Japan)