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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

2019 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
This is the final report for Project 6054-41000-110-00D, Developing Technologies that Enable Growth and Profitability in the Commercial Conversion of Sugarcane, Sweet Sorghum, and Energy Beets into Sugar, Advanced Biofuels, and Bioproducts. The replacement project, Improved Conversion of Sugar Crops into Food, Biofuels, Biochemicals, and Bioproducts, is currently under review and has not yet been assigned a Project Number. Progress was made on the project objectives, all of which fall under National Program 306, Component 1 (Foods), Component 2 (Non-Foods), and Component 3 (Biorefining). Progress on this project focuses on: Problem Statement 1A; define, measure, and preserve/enhance/reduce attributes that impact quality and marketability; Problem Statement 1C; new and improved food processing technologies; Problem Statement 2B; Enable technologies for (1) expanding market applications of existing biobased products, and (2) producing new marketable non-food biobased products derived from agricultural products and byproducts, and estimate the potential economic value of the new products; Problem Statement 2C; collaborate with breeders and production researchers in the development of both new cultivars/hybrids and new production practices/systems that optimize the quality and production traits of crop-derived products and byproducts for conversion into non-food biobased products; Problem Statement 3A; technologies for producing advanced biofuels (including biodiesel), or other marketable biobased products; Problem Statement 3B; technologies that reduce risks and increase profitability in existing industrial biorefineries; and Problem Statement 3C; accurately estimate the economic value of biochemical, thermolysis conversion technologies. In support of the objectives in general, the advantages of high performance analytical tools in the raw sugar factory were reviewed after four years of use and published in an industry-relevant journal so that other potential users may evaluate the benefits when troubleshooting and monitoring factory performance. In support of Objective 1, a detailed study of the various international methods for measuring total starch content in raw sugars was completed and the conclusions were published. Some of the most important findings were that current starch methods used in the sugar industry are negatively affected by natural cane and processing colorants, which often masks some measurements. Because existing industrial methods all use potato starch-based standards as references, the majority of the methods’ results seem interchangeable. Using the USDA Starch Research Method as a reference method, applied to factory raw sugars, ARS researchers in New Orleans, Louisiana, were able to clearly identify that a sample’s color affected the accuracy and precision of industrial methods of measurement currently in use. Methods that omitted a color corrective step were especially skewed. In addition, when compared, the methods are not mathematically equitable. The final findings on the development of an industrial method to measure starch in sugar products (e.g. juice, syrup, mud, and raw sugar) were published in an industry-relevant journal. Also in support of Objective 1 and Agreement 6054-41000-110-11S, the color reduction in raw sugar juice by potassium permanganate was investigated. Results show that the chemical selectivity of permanganate acts to oxidize color-inducing constituents (e.g., phenolics) while being unreactive with the desired sucrose components in the sugar cane juice. In addition, during reactions the permanganate is converted to solid phase products (called oxidation states) that can be readily removed by existing clarification steps within the sugar refining process stream. In support of Objective 3, investigation continued into the impact of storage (for more than a month) of sweet sorghum syrups prior to fermentation to fuels and chemicals. The results show that fermentation to biofuel ethanol was possible with syrups that had been stored for ten weeks under a thin layer of oil; however, syrups with 30% solids demonstrated substantial sugar degradation while little degradation occurred in syrups with 50% solids. In support of Objective 4, the study of the inhibitory effects on bioethanol production by aconitic acid (present in sweet sorghum juice and syrups) was completed. Aconitic acid has, in the past, been identified as a potential fermentation inhibitor. It was conclusively shown that aconitic acid negatively impacts fermentation rates of bioethanol-producing yeast and that the impact was pH dependent. During normal fermentation conditions, when pH levels were above 3.5, inhibition was insignificant. The final conclusions, based on study results, were published in an industry-relevant journal. Also in support of Objective 4, bacterial strains of Bacillus subtilis have been demonstrated to produce acetoin, a flavoring additive in the food industry and a precursor for industrial chemicals, using sugar beet and sweet sorghum syrups as the primary nutrient source. These strains underwent intermediate scale up for ultimate production and purification at commercial volumes. In support of Objective 5, we developed and published new statistical methods for field observation extraction and interpretation of information related to pest density and damage to sweet sorghum caused by sugarcane aphids. Also in support of Objective 5, the quality and processing attributes of sweet sorghum commercial hybrids and cultivars for the suitability of large-scale production of bioproducts in biorefineries were finalized. Two commercial sweet sorghum hybrids 105 and 106, later and earlier maturing, respectively, were compared to a popular Top 76-6 cultivar, for agronomic, quality, and processing attributes at two maturity stages. Overall, the hybrids processed similarly to the cultivar and had the additional advantages of having low starch and no side stalks. In support of Objective 6, we investigated the benefits of using a soil amendment combining biochar, worm castings and sugarcane bagasse compost products to improve soil quality. Worm castings can contribute beneficial microbes as well as physico-chemical enhancements to the soil. And compost produced from sugarcane bagasse byproducts may also be a potential soil enhancer. The texture of the worm castings and sugarcane bagasse compost was not ideal for even dispersal onto fields, however, the addition of biochar improved the texture without affecting the beneficial qualities of the worm castings. Microbial populations of the blends were found to contain taxonomic groups that contribute to plant health and did not contain human pathogens. Results indicate that blends containing 50% or less biochar will allow maintenance of beneficial microbes in stored samples. Also in support of Objective 6, we investigated the benefits of using biochar made from sugarcane bagasse as an amendment for soil-less growing media for the production of bean, squash and melon seedlings. As amendments to the soil-less growing media, the biochar functioned very well, especially at the 25% and 75% amendment levels. Even 100% biochar performed as well as the commercial soil-less growing media. Biochar mixture combinations compared favorably to the commercial media with low bulk densities and high water holding capacities. Future research is needed to evaluate these biochars for the production of additional plant species. Also in support of Objective 6, ARS researchers in New Orleans, Louisiana, developed a method of detecting biochar carbon by fluorescence and near-infrared-based chemometrics which proved to be a rapid, easy and inexpensive method to measure the amount of stable carbon stocks in agricultural soils. This method can be used to validate carbon stocks in diverse soil types in the presence of different soil amendments across the United States, allowing growers, land managers, and policy makers to quantify the carbon stocks on farms. The work was completed and the findings were published at the conclusion of the study. Also in support of Objective 6, ARS researchers in New Orleans, Louisiana, studied how compacting and ensiling impacts the stabilization of sweet sorghum bagasse. Greater bagasse stabilization translates into additional usage options, including novel applications. Bagasse stored for later use can be used as fuel, animal bedding and animal feed. Increased stability was obtained with inexpensive methods using commercially-available compactors and wrapping materials. The work was completed and the findings were published in an industry relevant journal. This work received the 2018 Southern Regional Research Center Technology Transfer Award.

1. Improved sugar processing. Raw sugar factories in Louisiana continue to experiment with additives to improve processing and sugar quality but microbial contamination continues to be problematic. ARS researchers in New Orleans, Louisiana, over the last three sugarcane harvesting seasons, have worked with a private company, testing a product (normally used for wastewater treatment) in the control of microbial contamination. During the last three seasons, five sugarcane factories in Louisiana applied the compound sodium permanganate to mill tandems and other factory locations. All of the participating factories recorded cleaner equipment, longer periods between required shut downs and cleaning due to contamination, reduced chemical cleaning costs, reduced use of expensive enzymes, and improved purity of sugarcane juice. After the second season of positive results, based on joint research, the private company launched a new product for the raw sugar industry. The established increase in sugar purity (or decreased loss of purity) was small but significant in terms of value. If this finding is verified in the upcoming harvesting season, it would potentially mean that a single factory would produce 2.1 million more pounds of sugar in a season which translates to $525,000 more revenue in a season.

2. Better and more efficient sugar processing. Processing sugar cane with high levels of trash such as brown and green leaves, weeds, soil and roots detrimentally impacts numerous factory operations and quality parameters of sugarcane juice processing. ARS researchers in New Orleans, Louisiana, conducted several factory trials at a local Louisiana mill that is co-located with a prototype mechanical detrasher. The studies revealed that processing efficiency improved relative to the amount of trash removed. The detrasher removed in excess of 50% of incoming trash material which allowed for higher recoverable sugar yields and stabilized variations in trash amounts providing a more consistent product for processing. The increase in processing efficiency represents a reduction of more than five days in the processing season, leading to several hundred thousand dollars in savings. In addition, the trash material, together with the bagasse (crushed sugarcane refuse), can be used to produce biochar which has applications from fuel to soil amendment and remediation.

3. Omics fingerprinting and machine-learning tools enabling a phytochemical-targeted breeding to restrict the use of pesticides, and to prevent the future outbreak of pesticide resistant strains. Since the outbreak in 2013, sugarcane aphid has become a perennial pest of sorghum production in the U.S. Although resistant varieties are available commercially and through germplasm gene banks, underlying mechanisms causing the aphid resistance are largely unknown. ARS scientists in New Orleans, Louisiana, developed advanced data mining methods to quantitatively trace target phytochemicals in a complex mixture of chemicals composing the sorghum stalk juice. Because the method is sensitive to naturally fluorescent chemicals, portable sensors could be deployed to expedite the breeding. Combined with the hyperspectral camera offering chemical fingerprints in each pixel of an image, fluorescence sensors will save time and labor costs associated with traditional visual scoring and post-harvest quality assurance/control.

4. Selective, low-cost and user-friendly electrochemical method to rapidly classify sorghum cultivars for food and biobased products. Recently, sorghum production for the consumer food industry has drastically grown in the U.S. This market trend originates from the health-promoting properties of antioxidants in sorghum. ARS scientists in New Orleans, Louisiana, developed electrochemical methods selective to antioxidants, while “masking” other chemicals. The method quantitatively measures different free radical quenchers engaging in reversible redox chemistry. The developed method identified a specific subgroup of antioxidants as the putative electron-shuttling defense phytochemical in a pest resistant sorghum cultivar.

5. Spreading information about sugar. In support of overall project objectives and under advice from stakeholders, ARS researchers in New Orleans, Louisiana, authored a book chapter on the history of sugars and sweeteners, as well as a college level text book chapter on carbohydrates and the industrial production of sugars. To further educate readers, a review journal article on the positive aspects of cane sugar and sugarcane derived products in food and nutrition was also published. Educating the public and students of science advances the knowledge that ARS generates. Informing readers about the critical need for sugar by human cells for proper function and the multitude of uses for sugars, other than sweetening, ensures the public’s knowledge of the relevance of ARS research programs.

Review Publications
Uchimiya, M., Franzluebbers, A.J., Liu, Z., Lamb, M.C., Sorensen, R.B. 2019. Detection of biochar carbon by fluorescence and near-infrared-based chemometrics. Aquatic Geochemistry Journal. 24:345-361.
Klasson, K.T. 2018. The inhibitory effects of aconitic acid on bioethanol production. Sugar Tech. 20(1):88-94.
Cole, M.R., Eggleston, G. 2019. Development of a new industrial method to measure starch in sugar products. International Sugar Journal. 121(1442):122-132.
Uchimiya, M., Knoll, J.E. 2019. Rapid data analytics to relate sugarcane aphid [(Melanaphis sacchari (Zehntner)] population and damage on sorghum (Sorghum bicolor (L.) Moench). Scientific Reports. 9:370.
Li, M., Wang, Y., Liu, M., Liu, Q., Xie, Z., Li, Z., Uchimiya, M., Chen, Y. 2019. Three-year field observation of biochar-mediated changes in soil organic carbon and microbial activity. Journal of Environmental Quality. 48(3):717-726.
Webber III, C.L., White Jr, P.M., Gu, M., Spaunhorst, D.J., Lima, I.M., Petrie, E.C. 2018. Sugarcane and pine biochar as amendments for greenhouse growing media for the production of bean (Phaseolus vulgaris L.) seedlings. Journal of Agricultural Science. 10(4):58-68.
Eggleston, G., Stewart, D., Aponte, F., Montes, B., Boone, S., Verret, C. 2018. How to use and interpret the results from a high performance liquid chromatography system at a sugarcane factory. International Sugar Journal. 120(1431):210-217.
Eggleston, G., Wartelle, L., Zatlokovicz III, J., Petrie, E., Cole, M., St Cyr, E. 2018. Quality attributes of sweet sorghum for the large-scale production of bioproducts: A 1-year comparison of commercial hybrids and a cultivar. Sugar Tech. 20(3):347-356.
Eggleston, G., Wartelle, L., Zatlokovicz III, J., Petrie, E., Cole, M., St Cyr, E., 2018. Processing attributes and performance of sweet sorghum biomass for large-scale biorefineries: A 1-year comparison of commercial hybrids and a cultivar. Sugar Tech. 20(3):336-346.
Eggleston, G. 2018. Positive aspects of cane sugar and sugarcane derived products in food and nutrition. Journal of Agricultural and Food Chemistry. 66:4007-4012.
Eggleston, G., Triplett, A. 2017. Formation of polyphenol-denatured protein flocs in alcohol beverages sweetened with refined cane sugars. Journal of Agricultural and Food Chemistry. 65:9703-9714.
Eggleston, G., Finley, J.W. deMan, J.M. 2018. Carbohydrates. In: deMan, J., Finley, J., Hurst, J., Lee, C.Y., editors. Principles of Food Chemistry, Food Science Text Series. 4th edition. New York, NY: Springer International Publishing. p. 165-229.
Cole, M., Eggleston, G. 2018. Comparison of international methods for the determination of total starch in raw sugars: Part II. Food Chemistry. 246:99-107.
Wright, M.S., Lima, I.M., Powell, R., Bigner, R.L. 2018. Effect of compacting and ensiling on stabilization of sweet sorghum bagasse. Sugar Tech. 20(3):357-363.
Webber III C.L., White Jr, P.M., Spaunhorst, D.J., Lima, I.M., Petrie, E.C. 2018. Sugarcane biochar as an amendment for greenhouse growing media for the production of cucurbit seedlings. Journal of Agricultural Science. 10(2):104-115.
Wang, Y.-M., Tang, D.-D., Zhang, X.-H., Uchimiya, M., Yuan, X.-Y., Li, M., Chen, Y.-Z. 2019. Effects of soil amendments on cadmium transfer along the lettuce-snail food chain: Influence of chemical speciation. Science of the Total Environment. 649:801-807.
Fang, Y., Ellis, A., Uchimiya, M., Strathmann, T.J. 2019. Selective oxidation of colour-inducing constituents in raw sugar cane juice with potassium permanganate. Food Chemistry. 298:125036.
Eggleston, G. 2019. History of sugar and sweeteners. In: Orna, M.V., Eggleston, G., Bopp, A.F., editors. Chemistry's Role in Food Production and Sustainability: Past and Present. ACS Symposium Series. Washington, DC: ACS Publications. 1314:63-74.