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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Commodity Utilization Research » Research » Research Project #426599

Research Project: Developing Technologies that Enable Growth and Profitability in the Commercial Conversion of Sugarcane, Sweet Sorghum, and Energy Beets into Sugar, Advanced Biofuels, and Bioproducts

Location: Commodity Utilization Research

2016 Annual Report

The overall objective of this project is to enhance the value of sugarcane, sweet sorghum, and energy beets, and their major commercial products sugar, biofuel and bioproducts, by improving postharvest quality and processing. Specific objectives are: 1. Develop commercially-viable technologies that reduce or eliminate undesirable effects of starch and color on sugar processing/refining efficiency and end-product quality. 2. Develop commercially-viable technologies that reduce or eliminate undesirable effects of high viscosity on sugar processing/refining efficiency and end-product quality. 3. Develop commercially-viable technologies to increase the stability and lengthen storage of sugar feedstocks for the manufacture of sugars, advanced biofuels, and bioproducts. 4. Develop commercially-viable technologies for the biorefining of sugar crop feedstocks into advanced biofuels and bioproducts. 5. Identify and characterize field sugar crop quality traits that affect sugar crop refining/biorefining efficiency and end-product quality, and collaborate with plant breeders in the development of new cultivars/hybrids to optimize desirable quality traits. 6. Develop, in collaboration with commercial partners, technologies to improve the efficiency and profitability of U.S. sugar manufacturing and enable the commercial production of marketable products from residues (e.g, bagasse, trash) and by-product streams (e.g., low purity juices) associated with postharvest sugar crop processing. Please see Project Plan for all listed Sub-objectives.

There are currently two major trends in the U.S. with respect to sugar crops: (1) the manufacture of higher quality raw sugar for supply to sugar refineries, and (2) the production of biofuels and bioproducts at new, flexible biorefineries. In recent years, mostly because of the increased harvesting of green sugarcane with leaves and tops, higher concentrations of starches and color have tended to occur. Some U.S. sugar refiners have placed a penalty for high starch concentrations in raw sugar. The occurrence of larger concentrations of insoluble starch in downstream factory products have exacerbated viscosity problems and reduced the efficiency of amylase enzymes to control starch. In close collaboration with industrial partners ARS scientists will develop new enzyme systems and other commercially viable technologies to control starch, viscosity, and color in factory and refinery streams, while also developing a method for measuring both insoluble and soluble starch in sugar products at the factory and refinery. Stable, storable, easily transportable, and available year-round supplies of sugar crop feedstocks, including sweet sorghum and energy beets, are needed for the conversion of sugars into substitute biofuels and bioproducts normally manufactured from fossil products. In close collaboration with industrial partners, ARS scientists will develop commercially-viable technologies for the extraction, stabilization, concentration, and fermentation of juices and syrups from sweet sorghum and energy beet feedstocks that will enable the deployment, growth, and profitability of new commercial biorefineries. Commercially-viable technologies will also be developed that are crucial to mitigate cultivar, seasonal, and environmental quality variations on feedstock performance.

Progress Report
Testing of Biofuels and Bioproducts with Sugar Solutions and Diluted Industrial Syrups. The biofuels and bioproducts ethanol, butanol, succinic acid (precursor to 1,4-butanediol), and acetoin were tested with chemical sugar solutions and diluted sugar crop syrups. A portion of the ethanol research were presented at the Symposium on Biotechnology for Fuels and Chemicals, Meeting on Advances in Sugar Crop Processing and Conversion, and at the Annual Meeting of the Society of Industrial Microbiology and Biotechnology. A week-long technical training trip was completed with an ARS-Peoria collaborator conducting butanol fermentation. The outcome allowed two commercially relevant organisms to be selected for butanol production and these have now been tested in the laboratory. Succinic acid was produced in an advanced reactor system using an organism, known for high productivity, from an ARS-Wyndmoor collaborator. Over sixty organisms were evaluated by a Japanese collaborator and two were selected for further study. They have now been tested on both sugar solutions and sugar crop syrup at New Orleans, Louisiana, with good results. Considering all the results obtained last year, most findings indicate that there was no significant difference between fermentation performance due to sugar source, except in the case of succinic acid. In the latter case, it was found that the organism did not convert sucrose (major sugar in syrups) in its native form. Thus, it will be required to break the sucrose into its smaller parts (glucose and fructose) before conversion. In some cases, nutrients in the diluted sugar crop syrups were not sufficient to support the growth of the microorganism used and needed to be supplemented. Physical Chemical and Microbial Properties of Stored Sugarcane Bagasse for Energy Production. Large amounts of excess sugarcane bagasse can be piled and stored from year to year outside sugarcane factories. In the previous year, we determined marked differences between higher (HHV) and lower (LHV) fuel heating values of bagasse due to the presence of moisture. High moisture levels negatively impacting bagasse fuel characteristics, and differences between HHV and LHV were as high as 57% for covered versus 81% for uncovered bagasse. Factory staff have concerns on the impact of the additional amounts of mud in the fuel value of the bagasse. For this reason, 2015 bagasse samples are being analyzed for fuel value and other pertinent chemical properties. This research has major implications for factories processers, who need the stored bagasse to burn in boilers and provide energy and steam to start-up the next processing season. Development of an Industrial Method to Measure both Insoluble and Soluble Starch. A new method was developed, that was urgently requested by industry, to measure insoluble, soluble and total starch in sugarcane products at the factory or refinery. The method was favorably tested against the USDA Research Method, and is less expensive. This new thermo-chemical method is very rapid at 2 min per sample and costs only 4 cents per sample. The method will now be validated following the protocols of the International Commission for Uniform Methods in Analysis and also validated for transferability at several sugarcane factories in 2016. Composting of Sweet Sorghum Bagasse. Samples of sweet sorghum bagasse were collected over the 2015 harvesting season and incubated in a commercially available composter across a period of 9 months. Samples were inspected regularly and at the end of the 9 month period it was determined that no significant beneficial conversion had occurred and the experiment was terminated. New Uses of Value-added Biochar from Sugarcane Bagasse and Trash. In 2016, we were approached by a Vermiculture and Animal farmer in Kentwood, LA on the potential to add value to worm castings (organic fertilizer) by blending with sugarcane biochar manufactured from bagasse and leafy trash. Worm castings were collected and blended with biochar at various volume-based percentages then stored at ambient temperature (25 degrees centigrade). After 42 days storage, microbial counts of 100% worm castings unwantonly dropped by approximately 85% and the addition of up to 10% biochar did not change this. At 25% addition of biochar to worm castings there was a significant enhancement of the microbial population, which may be due to biochar binding harmful microbial waste products. Biochar is beneficial because it is less expensive than worm castings, and blends stabilize the beneficial microbes in worm castings. Field Application of Value-Added Sugarcane Biochar. Sugarcane bagasse and leafy trash remain untapped by-products and residues, respectively. Three forms of biochar, manufactured from both bagasse and trash (pelletized, ground with and without molasses), were applied to sugarcane fields from two farms in South Louisiana in June 2015. Trenches were dug and biochar applied on both sides of each treated row, then covered with soil. Treated applications included first and second year sugarcane at both farms. In October 2015, soil was cored and sampled from each farm and stalks were counted. In November 2015, a representative sample of ten stalks was hand harvested from each treatment and processed at Houma. Analysis included stalk length and diameter, internode length, and stalk weight. Juice was analyzed for Brix (% dissolved solids), purity, and fiber content. Juice was plated for microbial presence. This study is being continued in a second year to determine continued effects of residual biochar. Identification of Microorganisms from Sugarcane and Sweet Sorghum Juices to Target Control Protocols. The microbial contamination of extracted sugar crop juice is a serious problem because it causes expensive sugar losses and the formation of degradation products that interfere with processing. We previously showed that commercial biocides do not work effectively. Identification of the microbes was necessary for more targeted control protocols. Using sophisticated methods, microbes were identified and measured in sugar crop juices. In addition, a sanitation questionnaire was developed and distributed to sugarcane factories in LA. The questionnaire will enable identification of unique processes at each factory that affect microbial populations. This research will lead to more efficient and effective methods to control microorganism populations and sugar losses in juices. Development of Laboratory Diffusion Method to Evaluate Pre-treated Sugar Crops. To perform diffusion experiments, a pilot-scale multi-feedstock (sweet sorghum, sugar cane, and energy beets) diffuser for juice extraction is needed. Because the manufacture of this custom-made system is expensive, industrial sponsorship is being sought. Meanwhile, a simple, flexible laboratory method was developed that mimics the countercurrent operation of a continuous diffuser into discrete sections. This method can yield diffusion data of interest, as well as optimum diffusion parameters which are not yet available particularly for sweet sorghum. The pre-treated (either sliced energy beets/shredded sweet sorghum) sugar crop is exposed to a series of sugar juices of decreased concentration and diffusion is allowed until there is no concentration gradient. At each stage of decreased sugar juice concentration, juice sub-samples can be collected and analyzed for fiber, polysaccharide, and other impurity contents. Variables studied include sample pre-treatment (shredding density, slice thickness), diffusion packing density, diffusion temperature, cultivar/variety and ratio of juice to sugar crop. This method has already been applied to energy beets. Final Progress Report on NIFA Grant. Nanotechnology is used in every industrial sector today, including agriculture. Industrial nanomaterials (very small particles less than 1 micron in size) enter agricultural soils as a sludge amendment or agrochemicals/fertilizers. Biochar has been promoted as the tool to convert U.S. soils into the soil found in archaeological site of Brazil (Amazonian terra preta). This project investigated how these foreign constituents influence the property of U.S. agricultural soils and associated ecosystems. Both biochars and nanomaterials changed the size of soil particle, resulting in the changes in key soil properties including the retention of water and nutrients. Furthermore, biochar helped food crops accumulate industrial nanomaterials to impact the nanotoxicology in the upper food chain of edible plants as well as the earthworm.

1. Technology for the long-term storage of sweet sorghum syrup. Sweet sorghum syrup is vulnerable to surface microbial spoilage during storage because of its rich sugar medium, and this represents a major technical challenge to the commercial, large-scale manufacture of biofuels and bioproducts from this feedstock. ARS scientists at New Orleans, Louisiana, with an industrial collaborator at Heckemeyer Mill, Sikeston, Missouri, showed that adding only a 1.7 cm layer of inexpensive soy bean, canola, or sunflower oil as a surface sealant, allowed sweet sorghum syrup containing 65% dissolved solids to be stored for at least 1 year at ambient temperature. Heckemeyer Mill is now using this novel technology to store syrup in 7,500 gal tanks.

2. Control of insoluble and soluble sugarcane starch by the application of amylases to factory clarification processes. The new knowledge that there is markedly more insoluble starch than previously considered in products across both the sugarcane factory and refinery has made the control of starch by amylase enzymes much more difficult. ARS scientists at New Orleans, Louisiana, with industrial collaborators Amano Enzyme in Japan and Alma sugarcane factory in LA, showed that both high-temperature (HT) and intermediate-temperature (IT) stable amylases can hydrolyze insoluble and soluble starch in clarified juice at 96 °C during the first 10 minutes before substantial breakdown of amylase protein. Unfortunately, however, even at 1 ppm, HT amylases can cause unwanted carry-over (residual) amylase activity in the raw sugar. Two new technologies were developed to prevent the occurrence of carry-over amylase in end-products: (i) the simultaneous addition of IT amylase to the next-to-the-last evaporator and last evaporator to hydrolyze both soluble and insoluble starch, and (ii) the addition of powdered activated carbon to remove the residual amylase protein with the added benefits of removing cane-derived phenolic/flavonoid colorants and insoluble starch.

3. Identification of quality and processing traits in sweet sorghum to aid breeders and industrial processors. Sweet sorghum is a promising feedstock crop for the manufacture of biofuels and bioproducts. ARS scientists at New Orleans, Louisiana, and at Houma, Louisiana, completed a two-year study on four commercial cultivars at five physiological stages. Juice quality and physical crop traits essential to processing and fermentation were strongly influenced by environmental and cultivar interactions; total sugars were influenced by cultivar and maturity interactions. Brix (per cent dissolved solids) in juice was shown not to be a valid in-field harvesting indicator to predict stalk maturity. Total sugars and starch in extracted juice were greatest at the hard dough (late) maturity stage but strongly depended on cultivar.

4. Testing of biofuels and bioproducts with sugar solutions and diluted industrial syrups. The biofuels and bioproducts ethanol, butanol, succinic acid (precursor to 1,4-butanediol), and acetoin were tested with sugar solutions and diluted industrial syrups from sugarcane and sugar beets. ARS scientists at New Orleans, Louisiana, and at Peoria, Illinois, transferred butanol fermentation technology, which allowed two commercially relevant organisms to be selected for butanol production and be tested in the laboratory. Also, succinic acid was produced in an advanced reactor system using an organism, known for high productivity, from an ARS-Wyndmoor collaborator. Out of sixty organisms evaluated by a Japanese collaborator, two were selected, and shown to give high yields with sugar solutions and sugar crop syrup fermentation feedstocks. Overall, except for succinic acid, most findings indicated that there was no significant difference between fermentation performance due to sugar source. For succinic acid manufacture it is necessary to break the sucrose into glucose and fructose, before conversion. In some cases, nutrients in the diluted sugar crop syrups were not sufficient to support the growth of the microorganism used and needed to be supplemented. These results will help to establish the large-scale manufacture of biofuels and bioproducts from sugar feedstocks.

5. Research method to measure insoluble and soluble starch in sugar products validated against international starch methods and used to pinpoint problems in carbonatation clarification process of sugarcane refineries. In recent years, starch impurity concentrations in sugarcane have been increasing in the United States. ARS scientists at New Orleans, Louisiana, developed a rapid, precise, and accurate research method based on microwave-assisted sound waves, to measure total, insoluble and soluble starch. This new research method has been successfully used to find commercially-viable solutions to reduce or eliminate profound detrimental effects on insoluble starch. It has also been used to pinpoint where soluble and insoluble starch cause problems during the carbonatation clarification system at sugarcane refineries. The method was also successfully compared to six, international starch methods commonly used in the sugar industry to measure total starch only, and results presented to the International Commission for Uniform Methods in Sugar Analysis.

6. Method to detect adulteration and misbranding of sweet sorghum syrups. Adulteration of sweet sorghum syrups has a strong economic impact on the industry and undeniable nutritional consequences. Furthermore, as sweet sorghum is a promising feedstock for the production of biofuels and bioproducts, the adulteration of syrups with high starch substitutes such as high fructose corn syrup (HFCS) could impact bio-yields. Some commercial sweet sorghum syrups can be fraudulently adulterated with inexpensive sugar syrups, particularly HFCS or corn syrup, and sold at a relatively low market price or even mis-branded. ARS scientists at New Orleans, Louisiana, showed that ion chromatography with integrated pulsed amperometric detection (IC-IPAD) fingerprint profiles can detect adulteration. Such profiles are extremely selective, sensitive, and reliable. By using five characteristic marker chromatography peaks of HFCS, in combination with a low sucrose peak, adulterated and mis-branded syrups were identified. The analysis of syrup samples containing 7% soluble solids allowed the detection of as low as 10% HFCS adulteration, which is within the lower limit of adulteration before action is taken. Detection of adulteration will allow for more fair competition, as well as stable markets and regional economies.

7. Developed methods for breeders and industrialists to characterize quality traits of sweet sorghum. Methods to rapidly, simply, and inexpensively measure quality traits in the new sweet sorghum feedstocks for the manufacture of biofuels and bioproducts are urgently needed. Breeders need them to develop better hybrids and cultivars and industrialists need them to measure feedstock quality and for grower payment systems. ARS scientists at New Orleans, Louisiana, developed several multivariate statistical methods for breeders to predict the key sweet sorghum genotype traits on-farm. Developed methods will replace currently available near-infrared and chromatography techniques by inexpensive fluorescence and light absorption methods. Developed methods will allow breeders and growers to predict the concentration of sugars or select impurities including aconitic acids, based on the maximum light absorption/reflectance by a juice/bagasse sample, and vice versa. Established chemometric (advanced statistical pattern recognition) methods were extended to sorghum grain samples to understand the chemical traits responsible for the pest (aphid/worm/bird) resistance.

8. Development of technologies to control color at the factory and refinery. Removal of cane or process-derived colorants, by separation methods or chemical breakdown methods, are the primary goal of sugarcane refiners. For optimum color removal, the chemical structure of colorants needs to be identified first. An ARS scientist at New Orleans, Louisiana, by using an advanced spectroscopic technique, revealed a relatively small amount of fingerprint phenolic structures (cane-derived colorants). Based on the identified structures, several different rapid, easy, and inexpensive research methods were developed to quantify the target colorants at the refinery. Based on the determined chemical structure and oxidation-reduction chemistry of the color, advanced oxidation technology, which is well established in water treatment, was determined to be the most promising chemical color removal approach that will continuously produce radicals to break down the color without forming toxic by-products.


Review Publications
Lima, I., Klasson, K.T., Uchimiya, M. 2016. Selective release of inorganic constituents in broiler manure biochars under different post-activation treatments. Journal of Residuals Science & Technology. 13(1):37-48.
Uchimiya, M. (2015) Biochar production technology: An overview. In: Ok, Y. S., Uchimiya, M., Chang, S., and Bolan, N., editors. BIOCHAR: Production, Characterization and Applications. London:Taylor & Frances. p. 45-66.
Yi, P., Pignatello, J.J., Uchimiya, M., White, J.C. 2015. Heteroaggregation of cerium oxide nanoparticles and nanoparticles of pyrolyzed biomass. Environmental Science and Technology. 49(22):13294-13303.
Uchimiya, M., Liu, Z., Sistani, K. 2016. Field-scale fluorescence fingerprinting of biochar-borne dissolved organic carbon. Journal of Environmental Management. 169:184-190.
Jones, K., Ramakrishnan, G., Uchimiya, M., Orlov, A., Castaldi, M.J., Leblanc, J., Hiradate, S. 2015. Fate of higher-mass elements and surface functional groups during the pyrolysis of waste pecan shell. Energy and Fuels. 29(12):8095-8101.
Cole, M.R., Eggleston, G., Borges, E., Thompson, J., Rathke, T., Naiki, J., Triplett, A. 2016. How the physical forms of starch affect filterability at a carbonatation refinery. Part I: Filterability of industrial sugars. International Sugar Journal. 118:204-213.
Eggleston, G., Heckemeyer, M., St Cyr, E., Wartelle, L. 2016. Case Study: Commercialization of sweet sorghum juice clarification for large-scale syrup manufacture. Sugar Tech. 18(3):249-257.
Eggleston, G., Lima, I. 2015. Sustainability issues and opportunities in the sugar and sugar-bioproduct industries. Sustainability. 7:12209-12235.
Eggleston, G., Andrzejewski, B., Cole, M., Dalley, C., Sklanka, S., St Cyr, E., Chung, Y., Powell, R. 2015. Novel storage technologies for raw and clarified syrup biomass feedstocks from sweet sorghum (Sorghum bicolor L. Moench). Biomass and Bioenergy. 81:424-436.
Cole, M.R., Rose, I., Chung, Y.J., Eggleston, G. 2015. A structured approach to target starch solubilization and hydrolysis for the sugarcane industry. Journal of Food Chemistry. 166:165–172.
Hale, A.L., Viator, R.P., Eggleston, G., Hodnett, G., Stelly, D., Boykin, D.L., Miller, D. 2016. Estimating broad sense heritability and investigating the mechanism of genetic transmission of cold tolerance using mannitol as a measure of post-freeze juice degradation in sugarcane and energycane (Saccharum spp.). Journal of Agricultural and Food Chemistry. 64(8):1657-1663. doi:10.1021/acs.jafc.5b03803.
Lima, I., Eggleston, G., Sarir, E., Donado, C.A., Thompson, J., Cyr, E.S. 2016. Mechanism of removal of undesirable residual amylase, insoluble starch, and select colorants from refinery streams by powdered activated carbons. International Sugar Journal. 118(1409):352-362.
Eggleston, G., Cole, M., Toyamasu, T., Triplett, A., Montes, B., Wartelle, L., Stewart, D. 2016. Conquering the control of insoluble and soluble starch with novel applications of amylase. International Sugar Journal. 120:570-579.