There exist large amounts of detergent fiber analysis data [neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL)] for many different potential cellulosic ethanol feedstocks, since these techniques are widely used for the analysis of forages. Researchers working in the area of cellulosic ethanol are interested in the structural carbohydrates in a feedstock (principally glucan and xylan), which are typically determined by acid hydrolysis of the structural fraction after multiple extractions of the biomass. These so-called dietary fiber analysis methods are significantly more involved than detergent fiber analysis methods. The purpose of this study was to determine whether it is feasible to correlate detergent fiber analysis values to glucan and xylan content determined by dietary fiber analysis methods for corn stover. In the detergent fiber analysis literature cellulose is often estimated as the difference between ADF and ADL, while hemicellulose is often estimated as the difference between NDF and ADF. Examination of a corn stover dataset containing both detergent fiber analysis data and dietary fiber analysis data predicted using near infrared spectroscopy shows that correlations between structural glucan measured using dietary fiber techniques and cellulose estimated using detergent techniques, and between structural xylan measured using dietary fiber techniques and hemicellulose estimated using detergent techniques are high, but are driven largely by the underlying correlation between total extractives measured by fiber analysis and NDF/ADF. That is, detergent analysis data is correlated to dietary fiber analysis data for structural carbohydrates, but only indirectly; the main correlation is between detergent analysis data and solvent extraction data produced during the dietary fiber analysis procedure.
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Acknowledgments The authors acknowledge Dr. Bonnie Hames, who originally suggested the possibility of correlating detergent fiber analysis data with dietary fiber data while employed at NREL. This work was supported by the US Department of Energy under Contract No. DE-AC36-99GO10337 with the National Renewable Energy Laboratory. Mr. Aaron Lorenz was supported by the USDA and DOE grant Integrated Feedstock Supply Systems for Corn Stover Biomass (Grant No. 144-144NR81). The authors also would like to acknowledge Dustin Eilert and Robert Vogelzang for technical assistance with the phenotypic evaluation of these materials and the support of the DOE-sponsored Great Lakes Bioenergy Research Center at the University of Wisconsin, Madison.
- Compositional analysis
- Corn stover
- Detergent fiber analysis
- Dietary fiber analysis