ABSTRACT
This chapter focuses on ethanol with a brief update on the recent advances in the generation of butanol via hydrolysis and fermentation technologies. During the past several decades, the hydrolysis and fermentation technologies to convert sugar or starch materials have been commercialized very extensively in the United States and Brazil among other countries. Today, there are two types of ethanol depending on the source of feedstock: grain ethanol and cellulosic ethanol. Ethanol production facilities for corn (grain) ethanol are classified into two broad categories: wet milling and dry milling operations. Starch is regarded as a long-chain polymer of glucose (i.e., many glucose molecular units are bonded in a polymeric chain similar to a condensation polymerization product). This starch is first broken down to simple sugar units by the hydrolysis process. The nonfermentable solids in distilled mash (stillage) contain variable amounts of proteins and fibers depending on the feedstock.
