Ethanol from Food Sources
Ethanol (C2H6O) is presently produced primarily from glucose from grain
(corn, maize, etc.), sugar (sugarcane), and energy crops using the fermentationbased
biochemical process. A typical process, as shown in Figure 9.3, comprises
the following major steps:
Milling: Corn is ground to a fine powder called cornmeal.
Liquefying: A large amount of water is added to make the cornmeal into a
solution.
Hydrolysis: Enzymes are added to the solution to break large carbohydrate
molecules into shorter glucose molecules.
Fermentation: The glucose mixture is taken to the fermentation batch
reactor, where yeast is added. The yeast converts the glucose into ethanol
and carbon dioxide as represented by the equation