Design of Processing Conditions for Conversion of Sugar and Starch Based Crops to Value Added Products.

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dc.contributor.advisor Mari S. Chinn, Committee Chair en_US
dc.contributor.advisor V. Den Truong, Committee Member en_US
dc.contributor.advisor Matthew W. Veal, Committee Member en_US
dc.contributor.advisor G. Craig Yencho, Committee Member en_US
dc.contributor.author Bridgers, Elizabeth Nicole en_US
dc.date.accessioned 2010-08-19T18:19:34Z
dc.date.available 2010-08-19T18:19:34Z
dc.date.issued 2010-05-03 en_US
dc.identifier.other etd-12212009-111605 en_US
dc.identifier.uri http://www.lib.ncsu.edu/resolver/1840.16/6317
dc.description.abstract This study focused on sweet sorghum and purple-fleshed industrial sweetpotatoes. Sweet sorghum is a crop which produces relatively high quantities of easy to process, directly fermentable aqueous sugar. Purple-fleshed industrial sweetpotatoes (ISPs) offer two viable resources for value added products in its combination of high dry matter (~32%) and anthocyanin content. The objectives of this project was to generate the information necessary to investigate the processing conditions for maximum ethanol production of sweet sorghum juice preparations, examine the effectiveness of different enzyme treatments on glucose and ethanol production as well as procedures for anthocyanin extraction from purple-fleshed industrial sweetpotatoes, and create a demonstration scale system for processing sweet sorghum and ISPs so that scale up processing conditions and related challenges can be studied. The effects of pH level, yeast type, incubation time and sterilization were investigated on sorghum juice preparations. Ethanol and individual sugar concentrations (sucrose, fructose and glucose) were measured over time. Sterile treatments typically resulted in >84% conversion of sugars to ethanol, while nonsterile treatments ranged between 60-75% conversion. Yeast type did not impact ethanol fermentation. Sterilization may not be necessary and generally will not support the most cost-effective process, while lowering pH and freezing could potentially preserve nonsterile fresh juice. The effects of different ISP preparations, enzyme loadings, and time on starch conversion and sugar production during liquefaction and saccharification were examined, in addition the effects of yeast concentration and salt supplementation on fermentation of produced sugars to ethanol were investigated. Results showed that the majority of available starch, 44.2 and 49.6% of dry matter, was converted during liquefaction of flour and fresh sweetpotato preparations, respectively, with the addition of 0.045 KNU-S/g dry ISP of Liquozyme SC after 2 hours incubation (68.8 and 67.0% initial starch contents, respectively). Saccharification was able to increase the breakdown of starch, but its primary function was conversion of short chain carbohydrate polymers to fermentable sugars. The addition of 5.0 AGU/g of Spirizyme Ultra was able to produce 644 and 582 mg/g starch in flour and fresh preparations, respectively. Yeast were able to produce 39.2 and 48.8 g/L of ethanol for flour (25% w/v substrate loading) and fresh (12.5% w/v) ISP, respectively, after 48 hours using 0.1% w/v yeast without salts. The effects of solvent type, solid loading, and incubation temperature on total monomeric anthocyanin and phenolic concentrations during extraction processing of purple-fleshed sweetpotatoes were determined. A subsequent hydrolysis process evaluated the effect of initial extraction conditions on the production of fermentable sugars. A maximum anthocyanin yield of 186.1 mg cyd-3-glu/100g fw was extracted from purple-fleshed ISPs. Greater recovery of anthocyanins was achieved at the higher extraction temperature of 80°C using acidified solvents. The sugars generated during hydrolysis of residual solids from extraction were not as easily fermentable as sugars derived from ISPs that had not undergone extraction. Residual solvent from the extraction process may have affected performance. Design and fabrication of a demo-scale hydrolysis and fermentation system for direct conversion of industrial sweetpotatoes and sweet sorghum juice was completed. Physical properties of each of the biomass materials were measured for use in vessel design and material handling considerations. Hydrolysis and fermentation tanks were capable of agitation, temperature control, environmental parameter monitoring, material introduction, and sampling. Material flow logistics through the system and a suitable control scheme were designed. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject ethanol en_US
dc.subject anthocyanins en_US
dc.subject extraction en_US
dc.subject fermentation en_US
dc.subject hydrolysis en_US
dc.subject purple industrial sweetpotato en_US
dc.subject sweet sorghum en_US
dc.title Design of Processing Conditions for Conversion of Sugar and Starch Based Crops to Value Added Products. en_US
dc.degree.name MS en_US
dc.degree.level thesis en_US
dc.degree.discipline Biological and Agricultural Engineering en_US


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