Abstract
Since our discovery of a strong raw starch digestion activity of black-koji amylase compared with yellow-koji amylase or malt amylase, we have investigated the reason why black-koji amylase has such a strong activity and researched the application of this activity to direct ethanol fermentation of starch materials without cooking.
The reason was explained by the following facts.
1) Black-koji amylase contains a larger amount of glucoamylase than yellow-koji amylase does.
2) Glucoamylase is the principal amylase on raw starch digestion.
3) Glucoamylase action on raw starch is stimulated by adding α-amylase.
Ethanol fermentation of starch materials without cooking was developed as follows.
1) Ethanol fermentation of sweet potato without cooking was carried out by using mold bran of Aspergillus awamori.
2) Ethanol fermentation of rice and corn without cooking was carried out by using submerged culture of Asp. awamori as amylase preparation.
3) Semi-continuous ethanol fermentation of corn starch without cooking was performed by using glucoamylase preparation of Asp. niger.
4) Ethanol fermentation of sweet potato without cooking was performed by using Rhizopus glucoamylase preparation.
5) Ethanol fermentation of cassava pellet without cooking was performed by using Rhizopus mold bran without adding yeast.
