Researchers found a way to turn raw starch into ethanol without cooking it first. They used a fungus called Aspergillus niger koji on wheat bran to break down the starch. The best conditions for this process were at a slightly acidic pH and a specific temperature. Corn and sweet potato starch worked best for making ethanol this way. It took 5 days to get the most ethanol using a mix of Aspergillus niger koji and dried yeast. When agitated, they were able to get about 95% ethanol yield from raw corn, sweet potato, and rice starch.