The researchers studied how different ratios of amylose and amylopectin in corn starch affect its fermentation characteristics. They mixed two types of starches with varying amylose: amylopectin ratios and used different enzymes for fermentation. They found that the ethanol yield varied depending on the starch composition and the type of enzyme used. Ethanol concentrations ranged from 2.2 to 9.1% for one type of enzyme and from 6.7 to 9.3% for another type.