The consequences of extracting com stover feedstock with either 95% ethanol or hot
water prior to the chemical analysis of the macrocomponents of that feedstock have been
determined. Reports by others have recommended the removal of extraneous substance
by solvent extraction prior to chemical analyses (Browning, 1967; TAPPI, 1988). The
95% ethanol extraction evaluated in this study is currently the "standard" method
recommended by the National Renewable Energy Laboratory, Golden, Co. Hot water
extractions were tested as a simple, less time consuming and less expensive alternative to
ethanol extractions. Compositional analyses involved the quantification of glycans, Klason
lignin, acid soluble lignin, ash, protein, acetic acid, and uronic acids.
The summative analysis of native, ethanol extracted and water extracted
feedstocks were all in the range of 97 to 98%. Ethanol extractions removed 4.9% of the
feedstock dry weight, compared to 17.2% of the dry matter being extracted with hot
water. The extractives obtained via ethanol had negligible amounts of glycans. In
contrast, the water extracted solids contained nearly 10% of the native feedstock total
glucan. Pre-extracting the feedstock with ethanol had little effect, relative to the native
feedstock, on the quantification of glycan components. In contrast, the water extracted
feedstock measured significantly lower in total glucans and total glycans than the native
feedstock. The lower values associated with the water extraction were due to the actual
extraction of glucans from the feedstock, and not due to analytical interferences associated
with the extractives. Ethanol and water extracted feedstocks measured significantly lower
in Klason lignin than the corresponding native feedstock. This was presumably due to the
removal of Klason lignin impurities present in the native feedstock, and not due to the
extraction of lignin itself.
The combined results from this study indicate that an informative approach to the
analysis of com stover feedstock would include the pre-extraction of the feedstock with
hot water prior to further analyses. The appropriate macrocomponent analyses should
then be done on both the extracted feedstock and the "extractives" obtained from that
feedstock. Analysis of the extracted feedstock, as compared to the native feedstock,
would provide more accurate estimates of the cellulose and lignin content of the
feedstock. The summative analysis of both the extracted solids and the extractives will
provide a reliable estimate of the total amount of carbohydrate potentially available in the
feedstock for microbial fermentation to ethanol. / Graduation date: 1996
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/25992 |
| Date | 29 May 1996 |
| Creators | Thammasouk, Khamphet |
| Contributors | Penner, Michael H. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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