Alcohol fermentation of corn starch without cooking was performed by using Chalara paradoxa glucoamylase preparation, which had stronger raw starch digesting activity than those of the conventionally known glucoamylases. A raw corn starch-enzyme-yeast mixture was fermented optimally at pH 5.0 and 30 degrees C for five days and produced ethanol. The yields of ethanol were between 63.5 and 86.8% of the theoretical value by baker's yeast (Saccharomyces cerevisiae), and between 81.1 and 92.1% of the theoretical value by sake yeast (Saccharomyces sake).

Three crude glucoamylase preparations from Rhizopus sp., Chalara paradoxa and Aspergillus sp. K‐27 were used to determine the digestibility of raw starches from eight sweet potato varieties. Granule sizes and amylose contents were also measured. The average granule sizes ranged between 10.5 and 14.2 μm. The amylose contents varied between 18.2 and 21.8%. The hydrolysis rates for the raw starches by any of the three glucoamylases were similar. However, starch of the variety Hi‐starch had a slightly lower hydrolysis rate than other starches when Rhizopus sp, enzyme was used.

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