Monday, April 30, 2007

Dilute acid hydrolysis of DDGS and corn fiber

Hossein Noureddini and Jongwon Byun. Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, 207 H Othmer Hall, Lincoln, NE 68588

Distillers dried grain with solubles (DDGS) and corn fiber are the co-products of the dry and wet corn milling industries, respectively. What constitutes these products is a mixture of protein, fat, fiber, and residual starch. Availability of DDGS and corn fiber at the ethanol plant and their high levels of lignocellulosic material makes them attractive feedstock for conversion to ethanol. In this study, dilute sulfuric acid hydrolysis for the conversion of DDGS and corn fiber to monomeric sugars was investigated. Biomass loadings in the range of 5 to 20%, w/v% at 5% intervals, acid concentrations in the range of 0.5 to 1.5, v/v% at 0.5% intervals and temperatures of 120 and 140 C were studied.  Experimental results confirmed an increasing trend in the formation of monomeric sugars as a function of time. The intensity of this trend correlated well with temperature, acid concentration and biomass loading. The highest concentration of monomeric sugars was observed when the maximum biomass lading was pretreated with the highest concentration of sulfuric acid and when the temperature was 140 C. For most of the cases under consideration, the most effective  period for the hydrolysis appeared to be during the initial 20 min of the reaction. Experiments were also performed to quantify moisture, extractives, starch, carbohydrates, lignin, and ash in DDGS and corn fiber samples. The total carbohydrate content of DDGS and corn fiber was 49.85 ± 0.51 w% and 69.89 ± 0.32 w%, respectively.