Tuesday, April 20, 2010
8-20

Fractionation of corn fiber by soaking in aqueous ammonia (SAA) pretreatment followed by hydrolysis using commercial enzymes

Justin Montanti1, Nhuan P. Nghiem2, David B. Johnston2, and Terry Walker1. (1) Biosystems Engineering, Clemson University, 221 McAdams Hall, Clemson, SC 29634, (2) Crop Conversion Science and Engineering, Eastern Regional Research Center, Agricultural Research Service, USDA, 600 E Mermaid Ln, Wyndmoor, PA 19038

Corn Fiber is a co-product of the corn wet-milling process that holds potential to become a value-added product. A process was developed to fractionate and isolate the hemicellulose B component of corn fiber. The process consisted of SAA pretreatment followed by cellulose hydrolysis, during which the Hemi-B was solublized by cleavage into xylo-oligosaccharides. The hemicellulose A and B fractions were separated by adjustment of pH, and the hemi-B recovered by precipitation with ethanol. The hemi-B was then hydrolyzed by a cocktail of enzymes that consisted of pectinase, xylanase, and ferulic acid esterase. Used by itself, the xylanase was very ineffective, demonstrating yields of less than 2% of xylose and arabinose. Pectinase alone exhibited xylose and arabinose yields of 34.49% and 47.20%, respectively.  The addition of ferulic acid esterase to the pectinase increased the yields to 44.44% of xylose and 52.89% of arabinose. Addition of xylanase to this mixture had no meaningful effect, increasing xylose yield by 0.03% while decreasing arabinose yield by 0.44%. Attempts to further characterize individual enzyme performance and to improve this yield are in progress, as is the completion of a mass balance around the process. These results will be discussed.