ABSTRACT
Enzymes are crucial in ethanol production from corn (Zea mays) and other starch sources. Enzymes in ethanol plants facilitate production of sugars used by yeast to yield ethanol through a fermentation process. They can also function as processing aids to reduce slurry viscosity, improve throughput, reduce deposits of organometallic salts or scale in processing equipment, reduce water usage and the overuse of other compounds such as acids and bases in ethanol production. Today, the ethanol produced in the United States comes mainly from plants employing dry milling technology (as discussed in Chapter 5). Besides carbon dioxide (CO2) and ethanol, dry-grind plants also produce distillers dried grains with solubles (DDGS). DDGS is increasingly counted as an economically important product of the ethanol production process rather than a coproduct or even less desirable coproducts. Deliberate focus on high nutrient digestibility, absence or low levels of antinutrients, and reduction in variability of DDGS can result in a signi„cant increase of ethanol plant’s revenues. Importantly, this can be even more crucial at times when ethanol production gives lower return on investment due to low fuel prices or high input cost such as high corn and energy (e.g., natural gas) prices.
