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
Objective 1: The optimal conditions for aqueous ammonia pretreatment have been established for corn fiber and DDGS. The pretreated materials were hydrolyzed with industrial enzymes to generate fermentable sugar solutions, which were successfully used for production of astaxanthin, one of the potential value-added co-products of ethanol in a biorefinery. Microorganisms that are known to produce the enzyme carbonic anhydrase have been identified. Work is in progress on acquiring these microorganisms, which will be used to produce the enzyme for use in succinic acid fermentation. Improvements in the application of enzymes for downstream dewatering and oil recovery in a corn to ethanol process have been made. A pilot scale trial of these processes was conducted at the National Corn to Ethanol Research Center to evaluate the effectiveness on a larger scale. Evaluation of these results is ongoing. Objective 2: Several new pretreatments and several new types of enzymes were identified that effectively increased the yields of corn oil from the dry milled and new generation corn germ using our ERRC aqueous enzymatic extraction method. Also, our ERRC aqueous enzymatic oil extraction process was evaluated and found to be effective for oil extraction with several species of oilseeds. Foaming can be used to concentrate the free oil in a fraction of the aqueous germ dispersion but the conditions used to digest the germ must not seriously degrade the compounds in the dispersion that stabilize the foam. To minimize the cost of centrifuging the foam fraction, it is important to maximize the oil content of that fraction. Significant improvement in the yield of free oil and free oil concentration in foam samples were obtained by changing the germ steam cooking and foam collection steps in the extraction and by using a combination of enzymes. About 80% of the oil obtained by hexane extraction can now be recovered in the foam fraction with the improved AEOE process; of this, 70% is free oil. First, most concentrated, samples of foam were 12 % free oil. Objective 3: A procedure to isolate water soluble hemicelluloses and water insoluble cellulosic fractions from ligno-cellulosic biomass by simple and economical steam treatment without using any acid or base was investigated. The yield of hemicelluloses was lower than obtained by standard hydrogen peroxide technology used previously in our laboratory. Corn fiber gum was also isolated by an environment friendly enzymatic treatment and is being characterized to determine its functional properties.
1. Cellulosic enzymes used to improve corn ethanol production. To improve economics of the fuel ethanol process, ARS researchers at Wyndmoor, PA, teamed up with University researchers to develop a new process to more efficiently remove water from the spent grains at the end of the fermentation. Water removal is presently a very expensive and energy-consuming process. To achieve this, the team added commercial enzymes developed for cellulosic ethanol production to the fermentor during corn ethanol production. The process was tested in a 54 million gallon per year ethanol plant in Illinois. Tests revealed that the new enzymatic process reduced overall facility water use by 10 percent, electricity consumption by 2.4 percent, and natural gas consumption by 12 percent. The process also reduced greenhouse gas emissions by approximately 8,000 tons of carbon dioxide per year. These improvements will greatly benefit the ethanol industry.
2. Determining the composition of corn oil produced from fuel ethanol plants helps to identify its value and new uses. The high price of corn and low price for ethanol creates low margins and an uncertain future for US ethanol plants. Recently, ethanol plants have begun to isolate crude corn oil as an additional coproduct of the ethanol process. ARS researchers at Wyndmoor, PA, teamed up with other researchers from ARS and private companies to determine the purity, composition, and uses of corn oil isolated from several stages of the corn ethanol process. It was determined that the recovered crude corn oil would require extensive and expensive refining before it could be used for food use but it would be acceptable as a feedstock for making biodiesel. It was also determined that the oil contained many high-value vitamins and nutraceuticals that could potentially be recovered prior to biodiesel production. Sale of these valuable coproducts along with the biodiesel feedstock-grade oil could help boost ethanol plant economics.
Mukhopadhyay, S., Onwulata, C.I., Yadav, M.P., Thomas-Gahring, A.E., Tunick, M.H. 2011. Thermophysical properties of starch and whey protein composite prepared in presence of organic acid and esters. Journal of Biobased Materials and Bioenergy. 5:10-8.