Various rice grain-like materials were prepared using rice bran, sake cake, corn starch and broken rice. They were used for preparing rice koji under various producing conditions such as incubation temperature, humidity and so on. The growth of fungi (
Aspergillus oryzae), and activities of the produced enzymes such a-amylase (
A Aase), glucoamylase (
G Aase), acid protease A Pase and acid carboxy peptidase (ACPase) were compared among prepared koji samples. The following procedures were found to be most suitable for obtaining higher GAase, AAase activities, and lower deferriferrichrysin (DF). 1 The testad grain samples containing 10% sake cake was soaked in water at high temperature (60°C), followed by showering with water. The suitable amount of water absorbed was 30%. 2; Inoculum size of mold was 0.03%. 3; Incubation temperature was 35-40°C. As an example, a moldy grain sample prepared showed enzyme activities as follows; AAase: 4, 400 units/g, GAase: 950 units/g, APase: 20, 000units/g and ACPase: 30, 000 units/g, which were four to five times those of the common rice koji.
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