Doctor of Philosophy / Department of Biological & Agricultural Engineering / Donghai Wang / Grain sorghum is the second major starch-rich raw material (after corn) for bioethanol
production in the United States. Most sorghum feedstock for bioethanol production is normal
non-tannin sorghum. Waxy sorghum and tannin sorghum are rarely used due to lack of scientific
information about waxy sorghum fermentation performance and the way to increase
fermentation efficiency of tannin sorghum. The main objectives of this study were to investigate
the fermentation performance of waxy sorghum and to improve fermentation efficiency of tannin
sorghum using techniques such as germination and ozonation treatments. The ethanol
fermentation performance on both waxy sorghum and tannin sorghum were evaluated using a
dry grind ethanol fermentation procedure. Fermentation efficiencies of tested waxy sorghum
varieties ranged from 86 to 93%, which was higher than normal (non-waxy) sorghum varieties.
The advantages of using waxy sorghums for ethanol production include less energy
consumption, higher starch and protein digestibility, shorter fermentation time, and less residual
starch in distillers dried grains with solubles (DDGS). Results from germination study showed
germination significantly increased fermentation efficiency of tannin sorghum. The laboratory
results were further confirmed by those from five field-sprouted grain sorghum samples.
Significantly increased free amino nitrogen (FAN) contents in sprouted sorghum samples
accelerated the ethanol fermentation process. Results from both laboratory-germinated and fieldsprouted
samples demonstrated that germination not only increased fermentation efficiency
(higher than 90%) but also reduced fermentation time by about 50%, which could result in
energy saving and increased production capacity without additional investment. The excellent
performance of sprouted sorghums may provide farmers a new market for field-sprouted
sorghum (poor quality as food or feed) in a bad year. A previous study showed ozone had a
strong connection to degradation of lignin macromolecules. The hypothesis was that ozone
treatment may also reduce tannin activity and increase fermentation efficiency of tannin
sorghum. Results showed that the ethanol production performance (ethanol yield, fermentation
efficiency, and fermentation kinetics) of the ozone-treated, tannin sorghum flours was
significantly improved compared with the untreated control. The other effects of ozonation on
sorghum flour include pH value decrease, discoloration, and inactivation of tannin. In summary,
these studies showed sorghum, no matter it was waxy, field-sprouted, or tannin sorghum, can be
an excellent feedstock for ethanol production.
| Identifer | oai:union.ndltd.org:KSU/oai:krex.k-state.edu:2097/9156 |
| Date | January 1900 |
| Creators | Yan, Shuping |
| Publisher | Kansas State University |
| Source Sets | K-State Research Exchange |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
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