Location: Sustainable Biofuels and Co-products Research
2018 Annual Report
Objectives
1. Develop processes to fractionate sorghum and corn/sorghum oils into new commercially-viable coproducts.
2. Develop processes to fractionate grain-derived brans into new commercially-viable coproducts.
2a: Develop processes to fractionate grain-derived brans into new commercially-viable coproducts such as lipid-based coproducts and for other industrial uses such as extrusion or producing energy or fuel.
2b: Develop commercially-viable, value-added carbohydrate based co-products from sorghum brans and the brans derived from other grains during their biorefinery process.
3. Develop processes to fractionate biorefinery-derived celluloses and hemicelluloses into new commercially-viable coproducts.
3a: Develop commercially-viable, value-added hemicellulose based co-products from sorghum biomass, sorghum bagasse and other agricultural based biomasses produced during their biorefining.
3b: Develop commercially-viable, value-added cellulose based co-products from sorghum biomass, sorghum bagasse and other agricultural based biomasses produced during their biorefining.
4. Develop technologies that enhance biodiesel quality so as to enable greater market supply and demand for biodiesel fuels and >B5 blends in particular.
4a: Improve the low temperature operability of biodiesel by chemical modification of the branched-chain fatty acids.
4b: Develop technologies that significantly reduce quality-related limitations to market growth of biodiesel produced from trap and float greases.
4c: Further develop direct (in situ) biodiesel production so as to enable its commercial deployment.
5. Develop technologies that enable the commercial production of new products and coproducts at lipid-based biorefineries.
5a: Enable the commercial production of alkyl-branched from agricultural products and food-wastes.
5b: Enable the commercial production of aryl-branched fatty acids produced from a combination of lipids and natural antimicrobials possessing phenol functionalities.
Approach
In conjunction with CRADA partners and other collaborators, develop technologies that identify new biorefinery coproducts, evaluate their applications and estimate their profitability and marketability. The approach will focus on development processes to produce several types of new coproducts. First, processes will be developed to extract and fractionate sorghum oil from sorghum kernels and sorghum bran. Processes will also be developed to extract and fractionated cellulose-rich and hemicellulose-rich fractions from sorghum kernels, sorghum bran, sorghum bagasse, and biomass sorghum. Other processes will be developed to improve the biofuel value of biodiesel by blending biodiesel with modified fatty acid derivatives to enhance its low temperature performance, reduce the levels of impurities that block fuel lines, economically convert trap grease and float grease to biodiesel, and improve the in situ process to make biodiesel directly from oil-rich low value agricultural products. In addition to biodiesel applications, other processes will be developed to produce branched fatty acids with unique functional (including improved lubricity) and biological properties (including antimicrobial and antioxidant properties).
Progress Report
Progress was made on all objectives, all of which fall under National Program 306 – Quality and Utilization of Agricultural Products, Component 3 Biorefining. Addressing Problem Statement 3.B. Technologies that reduce risks and increase profitability in existing industrial biorefineries.
Objective 1: Concerning the development of physical and centrifugation methods to fractionate Distillers Milo Oil, samples of this oil (from fuel ethanol plants fermenting only milo) and Distillers Milo/Corn Oil (from fuel ethanol plants fermenting mixtures of milo and corn at defined ratios) were dissolved in hexane, ethanol, and methanol. After incubating at various temperatures, the solutions were centrifuged and/or filtered to separate the solids and dissolved materials. The optimal combination of solvent and temperature was identified to efficiently separate the oil (triacylglcyerols) and waxes in Distillers Milo Oil. The composition of fractionated wax was then thoroughly characterized using both high performance liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry. The waxes fractionated from Distillers Milo Oil were found to be a mixture of surface waxes (mainly C28 and C30 alkanes, alcohols, aldehydes and acids) that originated from the surface of the sorghum kernel and nonpolar waxes (50-60 carbons) that were either produced or extracted during fermentation, ethanol distillation, or drying of the Distillers Milo Oil and Distillers Dried Grains and Solubles.
Objective 2: Sorghum bran (a fraction consisting of the outer layers of the kernel and representing ~10% of the mass of the kernel), compared to other typical cereal grains, has a unique composition because it contains high percentages of starch and protein. This allows sorghum bran to be potentially utilized for applications ranging from food products to composite materials such as bio-based plastics. For this work, we fractionated the sorghum grain by using a rice polisher to remove sorghum bran. To begin to study the extrusion applications of sorghum bran, a 1 kg sample was sent to collaborators at the ARS-Western Regional Research Center, where they utilized the material to prepare bio-based plastic material and compared the performance to materials prepared from other similar feedstock sources.
The study of the prebiotic properties (the ability to increase the proportions of “good” bacteria in the human colon) of sorghum bran was conducted via a growth study of 80 lactobacillus strains under both aerobic and anaerobic conditions. Unfortunately, the oligosaccharides from sorghum bran did not initiate the growth of these health-promoting bacteria. When sorghum bran was separated into a cellulose-rich fraction and a hemicellulose-rich fraction, the cellulose-rich fraction had interesting rheological (texture) properties, similar to those of catsup (a well known non-Newtonian shear thinning fluid). Like catsup, solutions of cellulose-rich fraction had a high viscosity but when force was applied (such as shaking the catsup bottle) there was a dramatic decrease in viscosity. These viscosity properties are very desirable for many food applications, as it implies that the material will pump easily and move through the processing equipment with very little difficulty but then, after high shear is removed, will resume the high viscosity needed for the application.
The hemicellulose-rich fraction (which contained high levels of arbinoxylans) from sorghum bran, sorghum bagasse, and biomass sorghum were used to make films for food applications. These films were prepared to determine water absorption and mechanical strength properties. The films were found to be quite sensitive to the surrounding relative humidity. The films from sorghum bran exhibited a 40% increase in mass at high relative humidity. An equilibrium condition of about 50% relative humidity appears to be the point where the rate of water absorption from the surroundings is the lowest. The films from each sorghum source have been prepared for mechanical strength testing. Once these analyses are complete the utilization of hemicellulose-rich fraction as a co-product can be directed towards either food or packaging applications.
Objective 3: Samples of pure oligosaccharides from the hemicellulose-rich fraction of sorghum bagasse (the fiber-rich material that remains after squeezing the juice from sweet sorghum) and biomass sorghum were generated and purified via a dialysis process. The study of their prebiotic properties was conducted. Unlike those from sorghum bran, the oligosaccharides from sorghum bagasse and biomass sorghum significantly increased the proportions of “good” bacteria in the human colon, demonstrating that they can potentially be useful as prebiotics. Interestingly, the oligosaccharides from the hemicellulose-rich fraction from sorghum bagasse and biomass are not as branched as those from sorghum bran.
The hemicellulose-rich fractions from sorghum bagasse and biomass sorghum did not make as good films as those from sorghum bran, which may be due to their less branched structure. The rheological (texture) study of the cellulose-rich fraction isolated from sorghum bagasse and biomass sorghum showed similar promising properties to those described above for the same fraction from sorghum bran. This implies that this material will also pump easily and move through the processing equipment with very little difficulty but then, after high shear is removed, will resume the high viscosity needed for many food applications.
Objective 4: Branched chain fatty acid additives were synthesized and are currently being evaluated by a collaborator for engine emissions and power testing. We have successfully identified several sulfur-containing compounds in biodiesel produced from ‘brown’ greases such as ‘trap’ grease and float greases using state-of-the art analytical instrumentation and protocols. These brown greases have been collected from local municipal underground grease traps and waste water treatment plants at various times of the year. In addition, we have successfully determined the efficiency of the in-situ transesterification process (a proprietary process developed at ERRC (Eastern Regional Research Center) that combines oil extraction and formation of biodiesel into one step) of the lipids in sorghum bran and post-fermentation sorghum stillage (material remaining after fermentation). Conversion of sorghum bran to biodiesel has been successful (>95%). The conversion of sorghum stillage to biodiesel using the in-situ method was increased from approximately a 30% yield to greater than 70% yield as a result of feedstock pretreatment and preliminary economic estimates have been conducted. Co-product meals are being collected for evaluation.
Objective 5: Isostearic acid and dimer acid were produced for lubricant and polyamide studies. To formulate the isostearic, isooleic acid (which is the precursor of isostearic acid) was blend with two base oils (i.e., polyalphaolefin (PAO-6) and high oleic sunflower oil). Lubricant properties (slipperiness) were evaluated by measuring the four-ball anti-wear friction and wear of the neat isooleic acid, oleic acid, and blends. Data on the physical properties including cloud and pour points, oxidation stability, kinematic viscosity and viscosity index were also collected. Results showed that blends (0 – 10 %, w/w) of isooleic and oleic acid in PAO-6 displayed the following similar trends with increasing concentration: mildly decreasing kinematic viscosity 40 and 100-degree C, increasing viscosity index number, lower coefficient of friction, and no change in wear. Blends (0 – 10 %, w/w) of isooleic and oleic acid in sunflower oil displayed the following similar trends: decreasing oxidation stability with increasing concentration, and constant pour point and cloud point with increasing concentration. Dimers, which are the major low value byproduct of isostearic acid production were successfully isolated by molecular distillation. Detailed characterization by mass spectroscopy showed that they are mixtures of different types of dimer products. Presently, methods for converting dimers into polyamide resins are being evaluated and will be followed by application studies. Studies were begun to evaluate the cytotoxicity of the phenolic-branched-chain fatty acid products using the pathogen-free chicken embryo method. The embryos were examined for any signs of internal or external abnormal development; all appeared to have developed normally. In other experiments it was demonstrated for the first time that heterogeneous catalysts such as zeolites and other types of acid catalysts, could be used to modify the structures of fatty acids in their natural state when they are naturally bound in common plant oils. In addition to modifying the oils by causing branching of their fatty acids it may also be possible to use catalysts to modify the oils in other ways, by attaching other molecules such as phenolics, which may give them new physical and biological properties such as antioxidant and antimicrobial properties.
Accomplishments
1. Catalytic modification of plant oils. Chemists at the Eastern Regional Research Center (ERRC) in Wyndmoor, Pennsylvania, demonstrated for the first time that heterogeneous catalysts such as zeolites and other types of acid catalysts, could be used to modify the structures of fatty acids in their natural state when they are naturally bound in common plant oils. Plant oils are comprised of natural compounds called triacylglcyerols. Previously, it was thought that only fatty acids in the free form or as fatty acid methyl esters could be modified by heterogeneous catalysts. The team demonstrated that oleic acid and other unsaturated fatty acids in sunflower oil could be modified by producing “branches” within the fatty acids. This newly modified type of plant oil has a lower melting point and may possess other valuable physical properties.
Review Publications
Marquez-Escalante, J.A., Carvajal-Millan, E., Yadav, M.P., Kale, M., Rascon-Chu, A., Gardea, A.A., Valenzuela-Soto, E., López-Franco, Y., Lizardi-Mendoza, J., Faulds, C.B. 2018. Rheology and microstructure of gels based on wheat arabinoxylans enzymatically modified in arabinose and xylose. Journal of the Science of Food and Agriculture. 98:914-922.
Deng, C., Liu, Y., Li, J., Yadav, M.P., Yin, L. 2018. Diverse rheological properties, mechanical characteristics and microstructures of corn fiber gum/soy protein isolate hydrogels prepared by laccase and heat treatment. Food Hydrocolloids. 76:113-122.
Nwokocha, L.M., Williams, P.A., Yadav, M.P. 2018. Physicochemical characterisation of the galactomannan from delonix regia seed. Food Hydrocolloids. 78:132-139.
Yadav, M.P., Hicks, K.B. 2018. Isolation, characterization and functionalities of bio-fiber gums isolated from grain processing by-products, agricultural residues and energy crops. Food Hydrocolloids. 78:120-127.
Qiu, S., Wang, Y., Chen, H., Liu, Y., Yadav, M.P., Yin, L. 2018. Reduction of biogenic amines in sufu by ethanol addition during ripening stage. Food Chemistry. 239:1244-1252.
Kale, M., Yadav, M.P., Chau, H.K., Hotchkiss, A.T. 2018. Molecular and functional properties of a xylanase hydrolysate of corn bran arabinoxylan. Carbohydrate Polymers. 181:119-123.
Liu, Y., Selig, M.J., Yadav, M.P., Yin, L., Abbaspourrad, A. 2018. Transglutaminase-treated conjugation of sodium caseinate and corn fiber gum hydrolysate: Interfacial and dilatational properties. Carbohydrate Polymers. 187:26-34.
Moreau, R.A., Nystrom, L., Whitaker, B.D., Moser, J.K., Baer, D.J., Gebauer, S.K., Hicks, K.B. 2018. Phystosterols and their derivatives: structural diversity, distribution, metabolism, analysis, and health promoting uses. Progress in Lipid Research. 70:35-61.
Yan, Z., Wagner, K., Fan, X., Nunez, A., Moreau, R.A., Lew, H.N. 2018. Bio-based phenolic-branched-chain fatty acid isomers synthesized from vegetable oils and natural monophenols using modified h+-ferrierite zeolite. Industrial Crops and Products. 114:115-122.
Sarker, M.I., Latona, R.J., Moreau, R.A., Micheroni, D., Jones, K.C., Lin, W., Lew, H.N. 2017. Convenient and environmentally friendly production of isostearic acid with protonic forms of ammonium cationic zeolites. European Journal of Lipid Science and Technology. 119(1700262):1-8.
Sarker, M.I., Lew, H.N., Moreau, R.A. 2018. Comparison of various phosphine additives in zeolite based catalytic isomerization of oleic acid. European Journal of Lipid Science and Technology. 120 (1800070):1-8.
Hughes, M., Jones, K.C., Hums, M.E., Cairncross, R.A., Wyatt, V.T. 2018. Identification of sulfur-containing impurities in biodiesel produced from brown grease. Journal of the American Oil Chemists' Society. 95:407-420.
Wyatt, V.T., Jones, K.C., Johnston, D., Moreau, R.A. 2018. Production of biodiesel via the in situ transesterification of grain sorghum bran and DDGS. Journal of the American Oil Chemists' Society. 95:743-752.
