Update on Ethanol Processing Residue Properties

Transcription

1 Iowa State University From the SelectedWorks of Kurt A. Rosentrater July, 2005 Update on Ethanol Processing Residue Properties Kurt A. Rosentrater, United States Department of Agriculture Kasiviswanathan Muthukumarappan, South Dakota State University James Julson, South Dakota State University Padmanaban Krishnan, South Dakota State University Available at:

2 An ASAE Meeting Presentation Paper Number: Update on Ethanol Processing Residue Properties Kurt A. Rosentrater, Ph.D., Agricultural and Bioprocess Engineer USDA, ARS, Crop and Entomology Research Unit 2923 Medary Avenue, Brookings, SD, 57006, K. Muthukumarappan, Ph.D., Associate Professor South Dakota State University, Department of Agricultural and Biosystems Engineering Ag Engineering 225, P.O. Box 2120, Brookings, SD, 57007, James Julson, Ph.D., Professor South Dakota State University, Department of Agricultural and Biosystems Engineering Ag Engineering 227, P.O. Box 2120, Brookings, SD, 57007, Padmanaban Krishnan, Ph.D., Professor South Dakota State University, Department of Food Science NFA 415, PO Box 2275A, Brookings, SD, 57007, Written for presentation at the 2005 ASAE Annual International Meeting Sponsored by ASAE Tampa Convention Center Tampa, Florida July 2005 Abstract. The production of corn-based ethanol in the U.S. is dramatically increasing, and consequently so is the amount of byproduct materials generated from this processing sector. These coproduct streams are currently solely utilized as livestock feed, which is a route that provides ethanol processors with a substantial revenue source and significantly increases the profitability of the production process. With the construction and operation of many new plants in recent years, these residuals do, however, have much potential for value-added processing and utilization in other sectors as well. This option holds promise of economic benefit for corn processors, especially if the livestock feed market eventually becomes saturated with byproduct feeds. Physical and nutritional properties, however, are needed for the proper design of processing operations and byproduct applications. Because information concerning ethanol byproduct materials is somewhat disparate outside the livestock arena, the objective of this study is to fully review the existing literature base and compile a physical and nutritional properties knowledge bank for these residual streams. This study will identify several gaps that currently exist in the knowledge base, which could thus provide fertile ground for future studies. Keywords. Byproduct Development, Characterization, Chemical Properties, Evaluation, Physical Properties, Processing The authors are solely responsible for the content of this technical presentation. The technical presentation does not necessarily reflect the official position of the American Society of Agricultural Engineers (ASAE), and its printing and distribution does not constitute an endorsement of views which may be expressed. Technical presentations are not subject to the formal peer review process by ASAE editorial committees; therefore, they are not to be presented as refereed publications. Citation of this work should state that it is from an ASAE meeting paper. EXAMPLE: Author's Last Name, Initials Title of Presentation. ASAE Paper No. 05xxxx. St. Joseph, Mich.: ASAE. For information about securing permission to reprint or reproduce a technical presentation, please contact ASAE at hq@asae.org or (2950 Niles Road, St. Joseph, MI USA).

3 Introduction With growing population, industrialization, and energy consumption pressures, coupled with an increasing reliance on nonrenewable fossil fuels, whose markets have historically been quite volatile, the energy security needs of North America continue to escalate. Biofuels, which are renewable sources of energy, can help meet these increasing needs, and can be produced from various biomass materials including residue straw, corn stover, perennial grasses and legumes, and other agricultural and biological materials. At the moment, the most heavily utilized is corn grain. Although directly tied to the market value of the grain itself, industrial ethanol production from corn is readily accomplished at a relatively low cost vis-à-vis other biomass sources. In fact, it is currently the only biological material that can be economically converted into ethanol on an industrial scale. The number of corn ethanol plants, and their processing capacities, has been markedly increasing in recent years. For example, in 2005, 87 manufacturing plants in the U.S. have an aggregate production capacity of 13.4 billion L/yr. Moreover, 16 plants are currently under construction, and will contribute an additional 2.6 billion L/yr (BBI, 2005; Lyons, 2003). As the ethanol market segment continues to grow, so have the quantities of residues that are generated from this industry. To effectively utilize and add value to these byproducts, physical and nutritional properties for these residual streams must be known. Characterization of byproduct materials provides data that are essential for livestock diet formulation, design of equipment and processing facilities, and optimization of unit operations (Ferris et al., 1995; Stroshine and Hamann, 1995). While much chemical and nutritional data has been determined as a result of livestock feeding trials, little physical property information has been gathered concerning these byproduct materials. Because the demand for corn-based ethanol has been greatly increasing in the United States during the last several years, the objective of this paper is to summarize and review the current state of knowledge regarding physical and chemical properties of corn ethanol manufacturing residues, so that subsequent value-added applications may be effectively investigated for these materials. Production Process and Byproduct Generation In-depth information on ethanol manufacturing processes, which is beyond the scope of this paper, can be found in Dien et al. (2003), Jaques et al. (2003), Tibelius (1996), and Weigel et al. (2005). Briefly, ethanol manufacturing from corn grain can be accomplished by a wet mill process, which is very capital intensive, or a dry mill process (Figure 1), which has less capital requirements, and thus is rapidly gaining momentum in the industry. The dry grind production process consists of several key steps, including grinding, cooking, liquefying, fermenting, and distilling the corn grain. Typically three main products are produced: bioethanol, the primary end product; residual nonfermentable corn kernel components, which are increasingly being marketed as distillers dried grains with solubles, known as DDGS (Figure 2); and carbon dioxide. Distillers grains are removed from the process stream during the distillation stage. They are dried, to ensure a substantial shelf life, and then sold to local livestock producers or shipped via truck or rail for use in distant livestock feed rations. The sale of distillers grains contributes substantially to the economic viability of ethanol manufacturing, and is thus a vital component to each plant s operations. Because of the dynamics of the free market economy under which this industry operates, the quantity of processing residues that will be produced can substantially influence the future of the industry. Anecdotally, the rule of thumb commonly used in industry states that for every 1 kg of corn processed, approximately 1/3 kg of each of the constituent product streams will be 2

4 produced. On a more scientific basis, it has been reported that the corn-to-ethanol conversion is approximately 2.58 kg corn / 1 L ethanol (Kim and Dale, 2002). Additionally, it has been reported that 25.4 kg of corn typically produces approximately 7.98 kg of ethanol, 8.35 kg of carbon dioxide, and 7.71 kg of DDGS (Kelsall and Lyons, 2003). This equates to a corn-todistillers grains conversion of 0.30 kg DDGS / 1 kg corn. Upon further investigation, it was found that literature actually reports a broad range of corn-to-distillers grains conversion rates (from to kg DDGS / 1 kg corn) (Dien et al., 2003; Kim and Dale, 2002; Lyons, 2003; Shapouri et al., 1995; Tibelius, 1996). These considerable variations will substantially affect the quantity of byproducts that are generated during ethanol processing. Moreover, at individual manufacturing plants, variations in raw material inputs, equipment used, and operational procedures result in conversion rates that do not match values found in literature, but instead vary stochastically over both time and location. Much of this information, however, is proprietary and is not available in the literature. Currently, the ethanol industry s only outlet for the nonfermentable residues from the manufacturing process, primarily in the form of distillers dried grains with solubles (DDGS), and to a lesser degree in the form of distillers dried grains (DDG), which do not have added solubles, distillers wet grains (DWG), and distillers solubles (DS), has been utilization as livestock feed ingredients. This approach is well established, but needs to be augmented if it is to retain its high-value return, especially as the generated quantities of these residues increase over time, as they are expected to due to the industry s near-term projected growth. Other novel uses, such as human foods and industrial products, or component extraction and conversion, should also be investigated. Fundamental to pursuing these alternate avenues is knowledge of the physical and chemical properties of these manufacturing residues. Physical Properties Very few researchers have investigated the physical properties of ethanol manufacturing residues. These sparse findings are summarized in Table 1. Essentially, research to date has determined that stillage fractions have relatively high BOD and COD levels, and that DDGS can have color that ranges from yellow to brown. Beyond these findings, however, there exists a great vacuum which remains to be filled. Physical characterization should encompass the comprehensive quantification of several key properties of the residue streams. From an engineering standpoint, the most essential physical properties include moisture content, water activity, density, yield stress, apparent viscosity, thermal conductivity, thermal diffusivity, heat capacity, and drying behavior (i.e., kinetics). Characterization of residue streams is essential because it provides data that are necessary for developing value-added utilization alternatives and, in fact, can actually determine which potential avenues are most appropriate for the specific residual streams under consideration: reprocessing, recycling, incinerating, composting, producing biomass energy, applying to land, feeding to livestock, or reusing via other value-added unit operations. Furthermore, material properties are critical to the engineering of equipment and facilities, and also to the design and optimization of specific processing operations, such as blending, mixing, separating, drying, extruding, heating, freezing, pumping, and conveying. Although not detailed here, several technical societies publish standard methods that are commonly used to quantify various physical properties of food and organic materials (AACC, 2000; AOAC, 2003; APHA, 1998; ASAE, 2005). 3

5 Chemical Properties As with many food and organic processing byproduct streams, feeding ethanol manufacturing residues to animals is a viable method for utilizing these residuals because they contain high nutrient levels. Over the years, numerous research studies have been conducted in order to optimize their use in feed rations. Aines et al. (1986) and UMN (2005) provide comprehensive reviews of this research. Moreover, much chemical and nutritional information for ethanol residues has been determined as a result of many of these investigations, including beef and dairy studies (Al-Suwaiegh et al., 2002; Clark and Armentano, 1993; Grings et al., 1992; Larson et al., 1993; Lodge et al., 1997; Schingoethe et al., 1999), non-ruminant livestock (Cromwell et al., 1993), as a function of manufacturing processes (Belyea et al., 1998; Belyea et al., 2004; Spiehs et al., 2002; Rasco et al., 1989; UMN, 2005), as well as other general investigations (Dong et al., 1987; Miron et al., 2001; San Buenaventura et al., 1987). Chemical composition data from these sources, as well as several others found in the literature, have been compiled and summarized for various ethanol manufacturing residues, including DDGS (Table 2), DDG (Table 3), DWG (Table 4), DS (Table 5), and TS (Table 6). This compilation will be an essential resource for those interested in developing value-added utilization alternatives for ethanol residues. Examining the information in these tables provides interesting insight, especially regarding the considerable variation which exists over research studies, ethanol plants producing these residues, and time. Chemical variation is, in fact, a considerable hurdle that must be overcome for effective utilization. Furthermore, this information is a valuable first step in determining mass balances for the ethanol manufacturing process. As shown in the tables, a considerable quantity of information has been determined for various residue streams, but additional work is needed to fill the gaps that exist in this database. Conclusions The bioethanol industry is poised to significantly contribute to meeting rising energy demands in coming years. Because this industry segment is not yet fully mature, questions have arisen regarding the nature of the industry itself, including the quantity of byproducts that will be generated. Considering how these residues will ultimately be utilized is essential to the future of the industry, and thus we face the pressing need for research and development efforts into value-added uses for these processing residue streams, if, given the current level of technology, the bioethanol industry is to remain cost-competitive. Options for utilizing these byproducts will be highly dependent upon both the physical and chemical properties of these materials, so it is imperative that these properties are fully quantified. This paper has taken a first step toward that effort by providing a summary and review of research to date. Much characterization work remains to be accomplished, however. References AACC Approved Methods of the American Association of Cereal Chemists, 10th ed., American Association of Cereal Chemists: St. Paul, MN. Aines, G., T. Klopfenstein, and R. Stock Distillers Grains, MP51. University of Nebraska Cooperative Extension. [online] URL: Al-Suwaiegh, S., K. C. Fanning, R. J. Grant, C. T. Milton, and T. J. Klopfenstein Utilization of distillers grains from the fermentation of sorghum or corn in diets for finishing beef and lactating dairy cattle. Journal of Animal Science 80:

6 AOAC Official Methods of Analysis of AOAC International, 17th ed., AOAC International: Gaithersburg, MD. APHA Standard Methods for the Examination of Water and Wastewater, 20th ed., American Public Health Association: Washington, D.C. ASAE ASAE Standards Standards, Engineering Practices, Data, 51st ed., American Society of Agricultural Engineers: St. Joseph, MI. BBI U.S. Production Capacity. Existing Plants. BBI International. [online] URL: Belyea, R. L., S. Eckhoff, M. Wallig, and M. Tumbleson Variability in the nutritional quality of distillers solubles. Bioresource Technology 66: Belyea, R. L., K. D. Rausch, and M. E. Tumbleson Composition of corn and distillers dried grains with solubles from dry grind ethanol processing. Bioresource Technology 94: Cromwell, G. L., K. L. Herkelman, and T. S. Stahly Physical, chemical, and nutritional characteristics of distillers dried grains with solubles for chicks and pigs. Journal of Animal Science 71: Clark, P. W. and L. E. Armentano Effectiveness of neutral detergent fiber in whole cottonseed and dried distillers grains compared with alfalfa haylage. Journal of Dairy Science 76: Dakota Gold Dakota Gold Marketing Enhanced Nutrition Distillers Products. [online] URL: Davis, C., M. Hutjens, and L. Berger Should you consider distillers and brewers byproducts? Hoards Dairyman 125(7): Dien, B. S., R. J. Bothast, N. N. Nichols, and M. A. Cotta The U.S. corn ethanol industry: an overview of current technology and future prospects. In The Third International Starch Technology Conference Coproducts Program Proceedings, eds. M. Tumbleson, V. Singh, and K. Rausch, 2-4 June, 2003, University of Illinois, pp Dong, F. M., B. A. Rasco, and S. S. Gazzaz A protein quality assessment of wheat and corn distillers dried grains with solubles. Cereal Chemistry 64(4): Ferris, D. A., R. A. Flores, C. W. Shanklin, and M. K. Whitworth Proximate analysis of food service wastes. Applied Engineering in Agriculture 11(4): Grings, E. E., R. E. Roffler, and D. P. Deitelhoff Responses of dairy cows to additions of distillers dried grains with solubles in alfalfa-based diets. Journal of Dairy Science 75: Jaques, K. A., T. P. Lyons, and D. R. Kelsall The Alcohol Textbook. Nottingham University Press: Nottingham, UK. Kelsall, D. R. and T. P. Lyons Practical management of yeast: conversion of sugars to ethanol. In The Alcohol Textbook, K. A. Jaques, T. P. Lyons, and D. R. Kelsall, eds. Nottingham University Press: Nottingham, UK. Kim, S. and B. E. Dale Allocation procedure in ethanol production system from corn grain. I. System Expansion. International Journal of Life Cycle Assessment 7(4): Larson, E. M., R. A. Stock, T. J. Klopfenstein, M. H. Sindt, and R. P. Huffman Feeding value of wet distillers byproducts for finishing ruminants. Journal of Animal Science 71:

7 Lodge, S. L., R. A. Stock, T. J. Klopfenstein, D. H. Shain, and D. W. Herold Evaluation of corn and sorghum distillers byproducts. Journal of Animal Science 75: Lyons, T. P Ethanol around the world: rapid growth in policies, technology, and production. In The Alcohol Textbook, K. A. Jaques, T. P. Lyons, and D. R. Kelsall, eds. Nottingham University Press: Nottingham, UK. Miron, J., E. Yosef, and D. Ben-Ghedalia Composition and in vitro digestibility of monosaccharide constituents of selected byproduct feeds. Journal of Agricultural and Food Chemistry 49: NRC United States Canadian Tables of Feed Composition, 3rd rev. National Academy of Sciences, National Research Council. Washington, DC. NRC Nutrient Requirements of Swine, 10th ed. National Academy Press, Washington, DC. San Buenaventura, M. L., F. M. Dong, and B. A. Rasco The total dietary fiber content of wheat, corn, barley, sorghum, and distillers dried grains with solubles. Cereal Chemistry 64(2): Schingoethe, D. J., M. J. Brouk, and C. P. Birkelo Milk production and composition from cows fed wet corn distillers grains. Journal of Dairy Science 82: Shapouri, H., J. A. Diffield, and M. S. Graboski Estimating the net energy balance of corn ethanol. Agricultural Economic Report NO U.S. Department of Agriculture. Spiehs, M. J., M. H. Whitney, and G. C. Shurson Nutrient database for distiller s dried grains with solubles produced from new ethanol plants in Minnesota and South Dakota. Journal of Animal Science 80(10): Stroshine, R. and D. Hamann Physical Properties of Agricultural Materials and Food Products. West Lafayette, IN: Copy Cat. Tibelius, C Coproducts and Near Coproducts of Fuel Ethanol Fermentation from Grain. Agriculture and Agri-Food Canada Canadian Green Plan Ethanol Program: Starchy Waste Streams Evaluation Project. [online] URL: UMN The Value and Use of Distillers Dried Grains with Solubles (DDGS) in Livestock and Poultry Feeds. [online] URL: Weigel, J. C., D. Loy, and L. Kilmer Feed Co-Products of the Dry Corn Milling Process. Iowa State University and Iowa Corn Promotion Board. [online] URL: Wilkie, A. C., K. J. Riedesel, and J. M. Owens Stillage characterization and anaerobic treatment of ethanol stillage from conventional and cellulosic feedstocks. Biomass and Bioenergy 19:

8 GRAIN STORAGE GRINDER VACUUM FLASH CO 2 SLURRY MIXER MASH COOKER COOKING TUBE JET COOKER LIQUIFACTION MASH COOLER YEAST STARTER FERMENTATION TANK DENATURANT ETHANOL MOLECULAR SIEVE RECTIFIER STRIPPING COLUMN DISTILLATION BEER WELL BACKSET THIN STILLAGE DS DDGS EVAPORATOR SYRUP WET CAKE DRYER WHOLE STILLAGE CENTRIFUGE DWG DDG DRYER Figure 1. Process flow diagram of a typical dry-grind corn-to-bioethanol manufacturing process. 50 mm 1 mm Figure 2. Nonfermentable residues distillers dried grains with solubles (DDGS). 7

9 Table 1. Physical properties of corn ethanol dry mill residues. Property Reported Values Reference Whole Stillage BOD (g/l) 37.0 Wilkie et al., 2000 COD (g/l) 56.0 Wilkie et al., 2000 Thin Stillage DDGS BOD (g/l) Wilkie et al., 2000 COD (g/l) Wilkie et al., 2000 Color Hunter L Value (-) Cromwell et al., Rasco et al., 1989 Hunter a Value (-) 1.4 Rasco et al., Cromwell et al., 1993 Hunter b Value (-) Cromwell et al., Rasco et al.,

10 Table 2. Chemical properties of corn distillers dried grains with solubles (DDGS) (%, d.b.). Property Reported Values Reference Dry Matter UMN, Cromwell et al., Spiehs et al., Dakota Gold, a Dong et al., Davis et al., a Lodge et al., NRC, 1998 Protein Cromwell et al., Davis et al., Spiehs et al., Belyea et al., UMN, Dakota Gold, Lodge et al., NRC, NRC, Grings et al., 1992 Amino Acids Alanine 1.83 Dakota Gold, 2005 Arginine Spiehs et al., Cromwell et al., UMN, Belyea et al., Grings et al., Dakota Gold, NRC, 1998 Aspartic Acid 1.76 Dakota Gold, 2005 Cystine 0.41 Dakota Gold, UMN, 2005 Glutamic Acid 4.60 Dakota Gold, 2005 Glycine 1.05 Dakota Gold, 2005 Histidine Spiehs et al., Belyea et al., Dakota Gold, UMN, Cromwell et al., NRC, Grings et al., 1992 Hydroxyproline 0.19 Dakota Gold, 2005 Isoleucine 0.92 Dakota Gold, Cromwell et al., Spiehs et al., UMN,

11 1.11 NRC, Grings et al., Belyea et al., 2004 Leucine 2.43 Belyea et al., NRC, UMN, Spiehs et al., Dakota Gold, Cromwell et al., Grings et al., 1992 Lysine 0.47 Grings et al., Spiehs et al., Cromwell et al., UMN, NRC, Belyea et al., Dakota Gold, 2005 Methionine 0.49 Dakota Gold, Spiehs et al., Cromwell et al., Belyea et al., NRC, UMN, Grings et al., 1992 Phenylalanine 1.27 Grings et al., Spiehs et al., Dakota Gold, UMN, Cromwell et al., NRC, Belyea et al., 2004 Proline 2.64 Dakota Gold, 2005 Serine 1.44 Dakota Gold, 2005 Threonine 0.77 Dakota Gold, Cromwell et al., Spiehs et al., Belyea et al., Grings et al., NRC, UMN, 2005 Tryptophan Cromwell et al., UMN, Belyea et al., Spiehs et al., Dakota Gold, NRC, 1998 Tyrosine 0.76 Belyea et al., Dakota Gold, Grings et al., 1992 Valine UMN, Dakota Gold,

12 Cromwell et al., Spiehs et al., NRC, Grings et al., Belyea et al., 2004 Fat UMN, Davis et al., Spiehs et al., a Dong et al., NRC, Belyea et al., Lodge et al., Dakota Gold, NRC, 1982 Carbohydrates UMN, 2005 Nitrogen Free Extract Spiehs et al., UMN, 2005 Starch Belyea et al., Lodge et al., 1997 Total Dietary Fiber 32.0 ± 7.8 San Buenaventura et al., 1987 Crude Fiber UMN, a Dong et al., Spiehs et al., Davis et al., Belyea et al., NRC, 1982 Neutral Detergent Fiber (NDF) 25.0 a Dong et al., Cromwell et al., Dakota Gold, Spiehs et al., NRC, Lodge et al., 1997 Acid Detergent Fiber (ADF) UMN, Dakota Gold, Spiehs et al., Belyea et al., Cromwell et al., NRC, Grings et al., 1992 Ash 2.0 Lodge et al., UMN, a Dong et al., Dakota Gold, Belyea et al., Davis et al., Cromwell et al., Spiehs et al., NRC, 1982 Ca UMN, Spiehs et al.,

13 0.04 Dakota Gold, NRC, 1998 P UMN, Spiehs et al., Dakota Gold, NRC, 1998 K UMN, Spiehs et al., NRC, Dakota Gold, 2005 Mg UMN, NRC, Spiehs et al., Dakota Gold, 2005 S UMN, NRC, Spiehs et al., Dakota Gold, 2005 Na UMN, Spiehs et al., Dakota Gold, NRC, 1998 Cl UMN, 2005 Zn (ppm) UMN, Spiehs et al., NRC, Dakota Gold, 2005 Mn (ppm) UMN, Spiehs et al., Dakota Gold, NRC, 1998 Cu (ppm) UMN, Spiehs et al., Dakota Gold, 2005 Fe (ppm) UMN, Spiehs et al., Dakota Gold, 2005 a %, wet basis 12

14 Table 3. Chemical properties of corn distillers dried grains (DDG) (%, d.b.). Property Reported Values Reference Dry Matter 85.8 Clark and Armentano, Davis et al., a Al-Suwaiegh et al., 2002 Protein 27.0 Clark and Armentano, Davis et al., Al-Suwaiegh et al., Miron et al., 2001 Fat 7.6 Davis et al., Clark and Armentano, Al-Suwaiegh et al., 2002 Total Carbohydrate Miron et al., 2001 Crude Fiber 12.8 Davis et al., 1980 Neutral Detergent Fiber (NDF) Clark and Armentano, Al-Suwaiegh et al., Miron et al., 2001 NDF Phenolics 4.87 Miron et al., 2001 Acid Detergent Fiber (ADF) 16.3 Clark and Armentano, Al-Suwaiegh et al., Miron et al., 2001 Acid Detergent Lignin (ADL) 11.1 Miron et al., 2001 Hemicellulose (NDF-ADF) 19.0 Miron et al., 2001 Cellulose (ADF-ADL) 17.2 Miron et al., 2001 Nonfiber Carbohydrate 9.8 Al-Suwaiegh et al., 2002 Glucose 22.8 Miron et al., 2001 Xylose 8.90 Miron et al., 2001 Arabinose 6.31 Miron et al., 2001 Galactose 2.95 Miron et al., 2001 Mannose 2.56 Miron et al., 2001 Uronic Acids 3.00 Miron et al., 2001 ND-Soluble Uronic Acids 1.34 Miron et al., 2001 ND-Soluble Glucans 9.30 Miron et al., 2001 Ash 2.0 Davis et al., 1980 a %, wet basis 13

15 Table 4. Chemical properties of corn distillers wet grains (DWG) (%, d.b.). Property Reported Values Reference Dry Matter 30.9 a Schingoethe et al., a Lodge et al., Larson et al., a Al-Suwaiegh et al., 2002 Protein 25.0 Larson et al., Lodge et al., Al-Suwaiegh et al., Schingoethe et al., 1999 Non-Protein Nitrogen 0.02 Schingoethe et al., 1999 Fat 8.5 Schingoethe et al., Larson et al., Lodge et al., Al-Suwaiegh et al., 2002 Fatty Acids Schingoethe et al., : Schingoethe et al., : Schingoethe et al., : Schingoethe et al., : Schingoethe et al., : Schingoethe et al., : Schingoethe et al., : Schingoethe et al., : Schingoethe et al., : Schingoethe et al., : Schingoethe et al., 1999 Neutral Detergent Fiber (NDF) 39.4 Larson et al., Al-Suwaiegh et al., Lodge et al., Schingoethe et al., 1999 Acid Detergent Fiber (ADF) 23.4 Schingoethe et al., Al-Suwaiegh et al., 2002 Lignin 7.4 Schingoethe et al., 1999 Nonfiber Carbohydrate 7.4 Al-Suwaiegh et al., 2002 Starch 4.6 Lodge et al., Larson et al., 1993 Ash 1.2 Lodge et al., Larson et al., Schingoethe et al., 1999 Ca 0.15 Schingoethe et al., 1999 P 0.71 Schingoethe et al., 1999 Mg 0.18 Schingoethe et al., 1999 a %, wet basis 14

16 Table 5. Chemical properties of corn distillers solubles (DS) (%, d.b.). Property Reported Values Reference Dry Matter Belyea et al., 1998 Protein Belyea et al., 1998 Amino Acids Arginine Belyea et al., 1998 Histidine Belyea et al., 1998 Isoleucine Belyea et al., 1998 Leucine Belyea et al., 1998 Lysine Belyea et al., 1998 Methionine Belyea et al., 1998 Phenylalanine Belyea et al., 1998 Threonine Belyea et al., 1998 Tryptophan Belyea et al., 1998 Tyrosine Belyea et al., 1998 Valine Belyea et al., 1998 Fat Belyea et al., 1998 Ash Belyea et al., 1998 Ca Belyea et al., 1998 P Belyea et al., 1998 K Belyea et al., 1998 Mg Belyea et al., 1988 Na (ppm) Belyea et al., 1988 Zn (ppm) Belyea et al., 1988 Mn (ppm) Belyea et al., 1988 Cu (ppm) Belyea et al., 1988 Fe (ppm) Belyea et al., 1988 Table 6. Chemical properties of corn thin stillage (TS) (%, d.b.). Property Reported Values Reference Dry Matter 5.0 Larson et al., 1993 Protein 16.8 Larson et al., 1993 Fat 8.1 Larson et al., 1993 Neutral Detergent Fiber (NDF) 11.7 Larson et al., 1993 Starch 22.0 Larson et al., 1993 Ash 5.9 Larson et al.,