There are a number of trends shaping the industry’s future. Wet millers will continue to develop value-added products for the starch stream and alternative uses for corn fiber. The dry-grind industry is looking at fractionating the corn prior to fermentation to realize better value from the corn, and at basic process modifications for lowering energy use [25, 26]. As is the case for corn fiber derived from wet milling, the dry-grind industry is also seeking alternate uses for its lowest value product, DDGS.

Alternative Feedstocks Corn Fiber

Wet mills have been investigating converting their least valuable residue from com processing (hulls and deoiled germ, known as corn fibers) into ethanol. Corn fiber is an attractive target for value-added research, because its value could be increased by converting it to ethanol instead of adding it to animal feed. The fiber is generated as a by-product at wet-milling facilities, and so there is no added cost for collection and transport of the material. Corn fiber contains 11-23% residual starch from wet milling and 12-18% cellulose (w/w, dry basis); the glucose in both polymers could be fermented to ethanol by traditional yeast. In addition, corn fiber contains 18-28% xylan and 11-19% arabinan. However, industrial yeast strains currently used for fermenting corn starch do not ferment arabinose and xylose, and the few naturally occurring yeast that do ferment pentoses produce low ethanol yields. Consequently, genetically engineered micro­organisms will be required for efficient conversion of pentose sugars to ethanol [27, 28]. A method to ferment the fiber to ethanol would increase ethanol yield from corn by 10%, while also generating feed coproducts with higher protein content [29]. Fermentation of corn fiber is being evaluated by Aventine Renewable Energy (Pekin, IL) to establish the process economics and robustness [30].