Skip to main content
ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Commodity Utilization Research » Research » Research Project #436409

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-Bridging Project

Location: Commodity Utilization Research

2020 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 byproduct 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 bridging project 6054-41000-111-00D that will terminate in September 2020. The final annual report for the previous project 6054-41000-110-00D was issued in FY2019. The title of the new project is “Improved Conversion of Sugar Crops into Food, Biofuels, Biochemicals, and Bioproducts.” The new project will focus on issues related to the processing of sugar crops for food use and the use of byproduct streams for food-based products and non-food biobased fuels, chemicals and products. There are three objectives in the new plan. Objective 1: Quantify the impact of new sugar processing aids (chemical oxidizers) in combination with existing ones (e.g., enzymes) on raw cane sugar manufacturing. Objective 2: Develop sustainable, commercially viable, biobased products from sugar cane and sugar beets byproducts (e.g., sugarcane bagasse, sugar beet pulp, clarifier mud/cake). Objective 3: Enable commercially viable, renewable biofuels and chemicals from sugar cane and sugar beet processing byproducts (e.g., molasses, clarifier mud/cake). Research progress was made on previous and new project objectives in FY2020, all of which fall under National Program 306, Component 1 – Foods, Problem Statement 1A: Define, Measure, and Preserve/Enhance/Reduce Factors that Impact Quality and Marketability; Component 2 – Nonfood (fibers including hides), Problem Statement 2B: Enable Technologies to Produce New and Expand Marketable Nonfood, Nonfuel Biobased Products Derived from Agricultural Feedstocks; and Component 3 – Biorefining, Problem Statement 3A: Viable Technologies for Producing Advanced Biofuels (including Biodiesel), or other Marketable Biobased Products. Progress is reported referencing the new plan objectives. In support of Objective 1, sugar factories in Louisiana continued to experiment with additives to improve processing and to improve sugar quality but microbial contamination continues to be the underlying problem and is difficult to control. ARS reseachers at New Orleans, Louisiana, have worked with a private company over the last four sugarcane harvesting seasons, testing a product to control microbes and reduce color. Past sugar factory experiments have shown promising results and received strong support from the sugar industry but long-term controlled experiments on full factory scale was lacking. Therefore, during the last season (Fall 2019), ARS reseachers at New Orleans, Louisiana, collaborated with a private company and a stakeholder group on a very large study that involved a sugarcane factory in Louisiana, and ARS reseachers at New Orleans, Louisiana, convinced them to use the compound sodium permanganate on a full-scale. Experiments with or without the compound were performed and hundreds of samples were collected and analyzed in our laboratory. Unfortunately, the harvesting season was about a month shorter than planned and full-scale duplicate experiments could not be performed. While some positive results were obtained, some questions still linger. Our continued collaborative work will focus on laboratory-scale and small-scale pilot scale studies at the factories. The collaborative research from previous years was presented at the International Society of Sugar Cane Technologists (ISSCT) Congress 2019 in Tucuman, Argentina and published in a stakeholder journal. Objective 1 and previous project objectives, raw sugar is successfully produced in Louisiana every season but the color of the sugar and left-over process additives such as enzymes reduce the value of the product when sold to sugar refineries. Therefore, ARS reseachers at New Orleans, Louisiana, investigated whether these compounds could be removed from raw sugar. The results from a pilot-scale study were published showing that powdered activated carbons could remove 38-55% of the color as well as 77-87% of enzymes added to improve sugar processing at raw sugar factories. The removal of these constituents reduces the monetary penalties imposed by sugar refineries on raw sugar factories for delivering lesser quality sugars. Proposals were submitted to the American Sugar Cane League by ARS reseachers at New Orleans, Louisiana, which resulted in two funded research agreements to perform preliminary work on the interaction between different oxidizers and enzymes used in sugarcane processing. Objective 2, clarifier mud from operating sugar factories is often seen as waste material and must be disposed of, but it may also serve as plant fertilizer and may be recycled back to sugarcane or soybean fields. ARS reseachers at New Orleans, Louisiana, collected clarifier mud samples from both Florida and Louisiana sugar factories which were evaluated and then stored for future experimentation. Although highly dependent on post-treatments and aging, it was found that Louisiana clarifier muds had promising phosphorus, potassium, and nitrogen content as well as premium organic fertilizer values. Also in support of Objective 2, a research agreement was established with a university partner to characterize the microbiome of sugarcane factory clarifier muds to better understand what organisms are present and better predict how they might affect soils to which the muds are applied. Microbial population, gene expression, and transcriptional analysis will be performed in which the DNA or RNA from microbial communities is analyzed to determine their identity, potential function and activity. Also in previous project objectives, ARS reseachers at New Orleans, Louisiana, reported at scientific meetings on the benefits of a single application of either biochar or sugarcane fly ash, individually, or in combination at two different rates, over four years of sugarcane crops. Biochars were produced from bagasse and leaf residue. Adding biochar to the soil consistently resulted in improvements in total sugar and total cane yield when compared to no treatment controls. Particularly, leaf waste biochar application led to increased sugarcane stalk count, cane yield, and sugar yield. Single application of either biochar and/or fly ash resulted in increased sugar yields over the 4 years as opposed to expected decreased yields. Cumulative profits and increased commodity value over several crop years can be foreseen with a single application of biochar. Best outcome for this study resulted in estimated sugar profits up to an additional $7,150 USD per hectare for leaf residue biochar versus no treatment. Also in support of this objective, sugarcane bagasse biochar was found to be a suitable replacement for bark in potted plant studies with collaborators. Objective 2 and Objective 3, waste biomass from agricultural operations can be used as starting materials for conversion into sugars and conversion of the sugars to biochemicals and biofuels. But there has always been a question about commercial viability. ARS researchers at New Orleans, Louisiana, evaluated production of chemical butanol from agricultural waste such as sweet sorghum bagasse. This study showed that many waste materials could serve as raw materials for butanol production via fermentation and materials that required less processing, such as food waste, were significantly cheaper to produce. The results have been published. In support of Objective 3, aconitic acid is present in sugarcane syrup and molasses and can possibly serve as a natural nematicide, but it must be extracted and tested for its efficacy against nematodes. Therefore, ARS reseachers at New Orleans, Louisiana, conducted preliminary extraction studies with aconitic acid containing samples and different extractants. Good extraction efficiency was obtained with several extractants. In addition, samples of sugarcane syrups were collected from the end of October 2019 to early December 2019 to see if there was a seasonal variability of aconitic acid in the syrup. The samples were frozen for future analysis. Large samples of clarification mud and sugarcane molasses from operating factories were collected and stored for experimentation. Objective 3, laboratory results were evaluated and published by ARS reseachers at New Orleans, Louisiana, showing that acetoin, an important chemical building block for chemical synthesis, can be produced via bacterial fermentation from sweet sorghum syrup and sugar beet thick juice. The research also showed that the conditions of the process could potentially be improved to reduce the cost. The research was performed with international collaborators. The results from another study, also in support of Objective 3, reported that there was loss of approximately 35-60% of sugars in sweet sorghum stalks (whole and cut) when stored for 4 days. The loss was slightly dependent on cultivar, but for both cultivars studied, the sugar loss was significant. Objective 3, a proposal was submitted by ARS reseachers at New Orleans, Louisiana, to Cotton Incorporated by which resulted in a funded agreement to investigate contaminant removal from sugar solutions obtained from solubilized discarded textiles, in order to ferment the sugar solutions to biochemicals. This is relevant as sugar solutions for fermentation may, in the future, come from simple sources such as sugar crops, or from residues from sugar crops, that must be chemically treated to release the sugars in a process that generates chemicals that inhibit subsequent fermentations. In support of previous project objectives, the results from a collaborative research study were published reporting that aconitic acid and some polyphenols (organic chemicals with ring structures) in sweet sorghum juice, as detected by a non-destructive analytical technique, may contribute to aphid resistance. Sweet sorghum is highly susceptible to damage by aphids, normally found in sugarcane. These findings, and new evaluation techniques, will help breeders select superior, pest-resistant sorghum cultivars with desirable nutritional values to enter the market at a faster pace.

1. Development of a process to stop degradation of sugarcane during temporary storage. Microbial deterioration of sugarcane starts as soon as it is harvested. The cane is commonly stored post-harvest awaiting processing, but during this time significant sugar losses ensue due to microbial action. Therefore, ARS researchers in New Orleans, Louisiana, continued working with a private company in testing liquid sodium permanganate application to the sugarcane during storage. Effectiveness was compared to other currently used products (bleach, biocide). Sodium permanganate was found to be the most effective treatment, performing better than bleach at preventing sugar loss to microbial contamination. An industrial process for applying treatment was outlined and a preliminary economic analysis was performed. The estimated annual revenue increase for the average Louisiana sugarcane factory was found to be approximately $1.95 million USD. Expanded to the entire Louisiana sugar industry, this early treatment system could increase the annual revenue of the industry by a net of 1.64% or $44.4 million USD.

2. Development of an antioxidant ranking of super-foods for prescription nutrition. High antioxidant and fiber content, and the gluten-free nature of sorghum increased its domestic production for the consumer food industry as a super-food by over 250% in the past five years. Sweet varieties of sorghum produce colorful sweeteners rich in antioxidants. However, sorghum antioxidant is a complex mixture of highly cultivar-dependent chemical structures, and consistency and quality are concerns if the antioxidants are to be used for prescription nutrition. Therefore, ARS researchers in New Orleans, Louisiana, developed a standardized technique for identifying antioxidants in sorghum. The electrochemical technique was used to measure the amount of electrons transferred to and from antioxidants, and what changes took place in the antioxidant chemical structures. Results were used to rank the antioxidant capacity of different sorghum food products. Colorful sweet sorghum varieties contained classes of compounds offering the highest antioxidant capacity. The new electroactive technique is broadly adaptable and could be used to rank the antioxidant capacity of emerging super-foods beyond sorghum.

Review Publications
Yu, P., Huang, L., Li, Q., Lima, I.M., White Jr., P.M., Gu, M. 2020. Effects of mixed hardwood and sugarcane biochar as bark-based substrate substitutes on container plants production and nutrient leaching. Agronomy. 10(2):156.
Boone, S., Ihli, S., Hartsough, D., Hernandez, L., Sanders, J., Klasson, K.T., Lima, I.M. 2020. Application of permanganate to reduce microbial contamination and sugar loss in raw-sugar production in Louisiana, USA. International Sugar Journal. 122(1456):254-260.
Eggleston, G., Lima, I., Schudmak, C., Hullet, R., Waguespack, Jr., H., Birkett, H., Gay, J., Landry, A., Finger, A. 2019. First year operation of a mechanical detrasher system at a Louisiana sugarcane factory -- impact on processing and value-added products. International Sugar Journal. 121(1449):682-691.
Wright, M. 2019. Impact of storage on sugar loss in sorghum stalks. African Journal of Agricultural Research. 14(33):1629-1634.
Wright, M., Klasson, K.T., Kimura, K. 2020. Production of acetoin from sweet sorghum syrup and beet juice via fermentation. Sugar Tech. 22(2):354-359.
Qureshi, N., Lin, X., Liu, S., Saha, B.C., Mariano, A.P., Polaina, J., Ezeji, T.C., Friedl, A., Maddox, I.S., Klasson, K.T., Dien, B.S., Singh, V. 2020. Global view of biofuel butanol and economics of its production by fermentation from sweet sorghum bagasse, food waste, and yellow top presscake: Application of novel technologies. Fermentation. 6(2). Article 58.
Lima, I.M., Jimenez, A.M., Eggleston, G., Pabon, B., Sarir, E., Thompson, J. 2020. Scale up studies for the simultaneous removal of colorants and protein from a refinery sugar liquor using powdered activated carbon - a pilot plant study. International Sugar Journal. 122(1459):488-495.
Uchimiya, M., Knoll, J.E. 2019. Accumulation of carboxylate and aromatic fluorophores by a pest-resistant sweet sorghum [Sorghum bicolor (L) Moench] genotype. ACS Omega. 4(24):20519-20529.
Uchimiya, M., Knoll, J.E. 2020. Electroactivity of polyphenols in sweet sorghum (Sorghum bicolor (L.) Moench) cultivars. PLoS One. 15(7):e0234509.
Wang, Y.-M., Wang, S.-W., Wang, C.-Q., Zhang, Z.-Y., Zhang, J.-Q., Meng, M., Li, M., Uchimiya, M., Yuan, X.-Y. 2020. Simultaneous immobilization of soil Cd(II) and As(V) by Fe-modified biochar. International Journal of Environmental Research and Public Health. 17(3):827.