Extraction and fermentation of ensiled sweet sorghum
Date
1987
Authors
Noah, Karl S., author
Linden, James C., advisor
Smith, Daniel, committee member
Dale, Bruce D., committee member
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Abstract
Sweet sorghum, variety Rio, was ensiled for 10 months prior to being subject to extraction studies using a pilot scale continuous countercurrent diffuser. An objective of the study was to see how control of liquid-solid ratio and diffusion temperature affected the recovery of sugars and organic acids from the ensiled sweet sorghum. Samples of the juice extracted from the sweet sorghum ensilage were fermented with Clostridium acetobutylicum and Saccharomyces uvarum to assure that no inhibitory or other detrimental substances were formed during the ensiling or extraction steps. As the liquid-solid ratio decreased, the diffusion juice component concentrations increased, but never to a level of fermentable sugars suitable for fermentation work. For a given change in ensilage sugar concentration over the length of the diffuser, it was found that not all of the liberated sugar was removed in the diffusion juice. Thus, even though greater than 90 percent of the components of the sweet sorghum were extracted, less than 90 percent of these components ended up in the diffusion juice. Therefore, the diffuser operated at unsteady state. Diffusion temperature had no effect on extraction efficiency. A model was applied to help predict diffuser performance. Only selected cases were found to provide satisfactory predictions. The organism best suited for fermentation of the concentrated ensiled sweet sorghum diffusion juice was C. acetobutylicum. The advantage of C. acetobutylicum was that in addition to sugars, it utilized lactic acid, the major fermentation product of ensiling. However, the C. acetobutylicum fermentations did not exhibit the acid break point; thus, small amounts of butanol were formed. No conclusions were possible pertaining to the formation of inhibitory substances during ensiling or extraction.
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Subject
Sorgo -- Silage
Silage -- Fermentation