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United States Department of Agriculture

Agricultural Research Service

Research Project: Value Added Coproducts for Improving the Economics and Greenhouse Gas Emissions of Corn and Cellulosic Fuel Ethanol Production

Location: Sustainable Biofuels and Co-Products

2012 Annual Report


1a.Objectives (from AD-416):
1: Develop technologies that enable commercially-viable* processes for producing new, valuable coproducts from DDGS, thin stillage, pentoses, CO2 or other byproducts of ethanol biorefining.

2: Develop technologies that enable new, commercially-viable* processes to produce food-grade corn oil, proteins, phytochemicals or other high-value coproducts from ethanol biorefineries.

3: Develop fractionation, enzymatic and/or chemical technologies that enable commercially-viable, high-value, non-fermentation hemicellulose- and cellulose-based coproducts from lignocellulosics.

* Potential commercial-viability will be regularly assessed with assistance from ONP, OTT and/or industrial partners.


1b.Approach (from AD-416):
Technologies will be developed that produce valuable coproducts from low value biorefining byproducts using innovative microbiologic, enzymatic and chemical processing strategies. Carbon dioxide from fuel ethanol facilities, currently vented or compressed for uses that eventually return it to the atmosphere, will be biologically incorporated into stable, industrially important chemical compounds using microalgae and other CO2 utilizing microorganisms. Commercially viable processes for removing food-grade oils, proteins, phytochemicals or other high value components from biorefinery feedstock fractions will be developed by innovative aqueous-enzymatic extraction and other novel technologies. Functional hemicellulose and cellulose-based products will be extracted from ligno-cellulosic feedstocks for use in foods and industrial products using enzymatic and chemical processing technologies. The successful development of these technologies will result in improved energy and environmental properties for biofuels, the potential sequestration of carbon into useful feeds and chemicals and an increased economic competitiveness of the US biofuels industry from the sale of new higher value coproducts.


3.Progress Report:
Optimum conditions for pretreatment of Distillers Dried Grains with Solubles (DDGS) using aqueous ammonia to improve subsequent bioconversion were determined. DDGS was pretreated and hydrolyzed with commercial enzymes and the released fermentable sugars were used as substrates for astaxanthin (an important carotenoid used in aquaculture feed) and ethanol production. The carbon dioxide produced in corn ethanol fermentations was converted to carbonates (the salt forms of carbonic acid) in an absorption column using different types of strong bases (sodium hydroxide, potassium hydroxide and ammonium hydroxide). The resulted carbonate solutions were subsequently used for pH control in succinic acid fermentations. The results were the same as those obtained in experiments where solutions of commercial carbonates (sodium carbonate, potassium carbonate and ammonium carbonate) were used for pH control, which were significant improvements over the use of sodium hydroxide, potassium hydroxide and ammonium hydroxide without carbon dioxide sparging into the fermentation broth. The optimization of enzyme use for enzymatic dewatering of the wet grains produced during corn to ethanol processing has been completed. Lower cost enzymes and the reduction in the amount of enzymes necessary to achieve dewatering have also been completed. Research demonstrating the additional effects on the downstream process is ongoing. The use of non-enzymatic agents will be investigated to determine if the effects can be further enhanced. The aqueous enzymatic extraction process yields of oil from dry milled corn germ were increased to about 75% using new combinations of commercial enzymes. Research was begun to evaluate the use of surfactants to further increase oil yields. The proximate composition of Miscanthus, corn stover, rice hulls, rice straws, sugarcane bagasse, and switch grass was determined. The water soluble components, starch, Hemicellulose A, Hemicellulose B, oligosaccharides, acid insoluble lignin, acid soluble components and the cellulosic residue from the above mentioned biomasses were isolated and their proximate and sugar compositions were determined. Research with a CRADA partner successfully resulted in the development of new and valuable corn bran-based bioproducts using the CRADA partner’s industrial waste stream as feedstock. A provisional patent has been filed on the technology and commercial sales of the product is imminent.


4.Accomplishments
1. Process for capture and use of carbon dioxide produced in an ethanol plant. ARS researchers at Wyndmoor, Pennsylvania have developed a process for capturing the carbon dioxide produced during ethanol fermentation as solutions of carbonates at near saturation concentrations. In liquid form these carbonate solutions can be transported to distant facilities for use in processes that require carbon dioxide as a feedstock. The implementation of the developed process will eliminate the requirement for a plant using a carbon dioxide requiring process to be located immediately adjacent to a carbon dioxide source. It has been demonstrated that the carbonate solutions could be used for pH control in succinic acid fermentation. It is anticipated that these carbonate solutions can also be used in other processes that has a carbon dioxide fixing step, for example, growth of algae for production of fuels and chemicals.


Review Publications
Yadav, M.P., Nunez, A., Hicks, K.B. 2011. Isolation, purification and identification of protein associated with corn fiber gum. Journal of Agricultural and Food Chemistry. 59:13289-13294.

Kim, E., Kwon, T., Um, B., Moreau, R.A., Choi, S. 2012. Anti-inflammatory activity of hydroxycinnamic acid derivtives isolated from corn bran in lipopolysaccharide-stimulated raw 264.7 macrophages. Food and Chemical Toxicology. 50:1309-1316.

Samala, A., Srinivasan, R., Yadav, M.P., Kim, T., Prewitt, L. 2012. Xylo-oligosaccharides production by autohydrolysis of corn fiber separated from DDGS. BioResources. 7(3):3038-3050.

Yadav, M.P., Moreau, R.A., Hotchkiss, A.T., Hicks, K.B. 2011. The development of a new corn fiber gum isolation process that preserves its functional components. Carbohydrate Polymers. 87:1169-1175.

Moreau, R.A., Johnston, D.B., Haas, M.J, Hicks, K.B. 2012. Aqueous extraction of corn oil after fermentation in the dry grind ethanol process. In: Farr, W., Proctor, A., editors. Green Oil Processing. Urbana, IL: AOCS Press. p. 53-70.

Last Modified: 4/24/2014
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