Fiber Separated from Distillers Dried Grains with Solubles as a Feedstock for Ethanol Production

Abstract

ABSTRACTIn the dry‐grind process, corn starch is converted into sugars that are fermented into ethanol. The remaining corn components (protein, fiber, fat, and ash) form a coproduct, distillers dried grains with solubles (DDGS). In a previous study, the combination of sieving and elutriation (air classification), known as the elusieve process, was effective in separating fiber from DDGS. In this study, elusieve fiber was evaluated for ethanol production and results were compared with those reported in other studies for fiber from different corn processing techniques. Fiber samples were pretreated using acid hydrolysis followed by enzymatic treatment. The hydrolyzate was fermented using Escherichia coli FBR5 strain. Efficiency of ethanol production from elusieve fiber was 89–91%, similar to that for pericarp fiber from wet‐milling and quick fiber processes (86–90%). Ethanol yields from elusieve fiber were 0.23–0.25 L/kg (0.027–0.030 gal/lb); similar to ethanol yields from wet‐milling pericarp fiber and quick fiber. Fermentations were completed within 50 hr. Elusieve fiber conversion could result in 1.2–2.7% increase in ethanol production from dry‐grind plants. It could be economically feasible to use elusieve fiber along with other feedstock in a plant producing ethanol from cellulosic feedstocks. Due to the small scale of operation and the stage of technology development for cellulosic conversion to ethanol, implementation of elusieve fiber conversion to ethanol within a dry‐grind plant may not be currently economically feasible.