Abstract
1. Ethanol fermentation of rice without cooking was performed by using black-koji amylase. From 14 to 15 vol% of ethanol was successfully produced in rice powder broth at 30°C and pH 3.5 for 5 to 10 days. 2. Semi-continuous ethanol fermentation of corn starch or cassava starch without cooking was carried out by using black Aspergillus glucoamylase preparation. Raw starch was mixed with Asp, niger glucoamylase preparation, water and yeast at pH 3.5 and 30°C. After one day fermentation, about 10 vol% of ethanol produced in the broth was distilled out in vacuum and the residue was reused as a source of amylase arid yeast for the next fermentation. Such fermentation process could be repeated forr twenty days, during which one dialysis was performed. 3. Ethanol fermentation of cassava roots or sweet potato roots without cooking was performed by using Asp. niger glucoamylase preparation or black Asp. mold bran. From 12 to 13 vol% of ethanol was produced in cassava broth at pH 3.5 and 30°C for five days. About 10 vol% ethanol was produced in sweet potato broth at pH 3.5 and 38°C for 3-4 days. 4. Rhizopus glucoamylase preparation could be used in ethanol fermentation of sweet potato without cooking at pH 4.5 and 38°C for 3-4 days, in which 0.02% of potassium pyrosulfite must be added to protect the contamination.
