Erik D. Sall

Ethanol Production from Modified and Conventional Dry-Grind Processes Using Different Corn Types

ABSTRACT Different corn types were used to compare ethanol production from the conventional dry-grind process to wet or dry fractionation processes. High oil, dent corn with high starch extractability, dent corn with low starch extractability and waxy corn were selected. In the conventional process, corn was ground using a hammer mill; water was added to produce slurry which was fermented. In the wet fractionation process, corn was soaked in water; germ and pericarp fiber were removed before fermentation. In the dry fractionation process, corn was tempered, degerminated, and passed through a roller mill. Germ and pericarp fiber were separated from the endosperm. Due to removal of germ and pericarp fiber in the fractionation methods, more corn was used in the wet (10%) and dry (15%) fractionation processes than in the conventional process. Water was added to endosperm and the resulting slurry was fermented. Oil, protein, and residual starch in germ were analyzed. Pericarp fiber was analyzed for residual st...

Effect of Wet and Dry Fractionation Methods on Ethanol Production from Hard and Soft Endosperm Corn Types

Two corn fractionation methods, wet and dry, were compared to the conventional dry grind process using hard and soft endosperm corn types. Fractionation methods remove germ and pericarp fiber prior to fermentation. Wet fractionation involves soaking of corn and grinding, followed by germ and pericarp fiber removal. In dry fractionation, corn is tempered and passed through a roller mill before the germ and pericarp fiber are removed. Hard and soft endosperm types differ in the protein starch interactions, shape of starch granules, and type of proteins present. Effect of hard and soft endosperm on wet and dry fractionation processes and the conventional process were analyzed for final ethanol concentrations and fermentation rates. Germ from fractionation processes was analyzed for yield, oil, protein, and residual starch contents. Pericarp fiber yields, residual starch, and NDF contents were determined. Soft endosperm corn resulted in higher final ethanol concentrations (15.8%) than hard endosperm corn types (15.5%). Germ yields from hard endosperm corn were 1.8% higher than soft endosperm corn types. Pericarp fiber yields were higher from soft endosperm corn (10.8%) than from hard endosperm corn (8.35%). Among processes, wet fractionation resulted in 0.5% and 1.8% v/v higher final ethanol concentrations than dry fractionation and the conventional process, respectively. Germ yields were higher from dry fractionation (10.6%) than from wet fractionation (8.35%). Germ fractions from wet fractionation had higher oil (31.4%) and protein (14.2%) than germ from dry fractionation (18.8% and 12.6%, respectively). Dry fractionated germ had 6.9% more starch than wet fractionated germ. Pericarp fiber yields were higher from wet (11.4%) than from dry (7.21%) fractionation. Fractionation processes result in higher final ethanol concentrations and can provide valuable coproducts.

High Fermentable Corn Hybrids for the Dry-Grind Corn Ethanol Industry

The biofuel corn ethanol helps provide a sustainable and secure non-petroleum source of energy. The dry-grind ethanol industry is the customer for about one-third of US-produced corn grain. Getting the most ethanol from sourced corn grain is important to the economics of a commercial ethanol plant. Near infrared transmittance spectroscopy (NIT), backed by calibrations built with robust reference chemistry, is used to predict the fermentability of whole corn grain. Ethanol yield predicted by NIT has been shown to be highly correlated with commercial ethanol yield. High fermentable corn hybrids identified using NIT have been designated by commercial seed producers and made available to corn growers. The combination of a robust, commercially validated NIT calibration and a rigorous corn hybrid designation process has been used to identify high fermentable corn hybrids to enable higher ethanol yields for the dry-grind ethanol industry.