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United States Department of Agriculture

Agricultural Research Service

Research Project: ENHANCED END USE QUALITY AND UTILIZATION OF SORGHUM GRAIN

Location: Grain Quality and Structure Research Unit

2005 Annual Report


1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter?
In recent years, sorghum production has declined in the U.S. Sorghum is a low-input, drought-tolerant crop grown in several parts of the U.S. and around the world. Sorghum is used primarily as animal feed in the U.S. (second only to maize), although ~30 to 40% of worldwide production is used as human food. In 1998, the U.S. produced ~20% of the worldwide sorghum supply. Annually, ~30 to 50% of the U.S. sorghum crop is exported. Therefore, new uses for sorghum could represent new markets for U.S. agriculture. In addition, the drought-tolerance of sorghum makes it attractive for future growth in areas of low water availability. Increased utilization of sorghum could serve as a tool for rural renewal in areas where sorghum is a major crop and where water is limited for production of other crops such as maize and soybeans.

Sorghum has potential for several uses including a source of renewable bio-industrial products such as ethanol, lactic acid, and biodegradable films and packaging. Sorghum also represents a safe food for people who cannot eat wheat. However, several obstacles must be overcome in order to increase the utilization of sorghum. While some research directed at using sorghum in food products and industrial products (such as biodegradable films) has been carried out, comparatively little research has been conducted on the relationship between sorghum biochemistry and end-use quality and utilization.

This project will focus on the relationships between sorghum biomolecules and end-use quality and utilization of sorghum. Understanding these relationships will identify the components of sorghum that are responsible for end-use quality. Knowledge of these relationships will also allow for new uses of sorghum to be developed.

This project addresses USDA-ARS National Program 306, Quality and Utilization of Agricultural Products. The vision of this National Program is to “provide knowledge and innovative technologies that lead to new and expanded market opportunities for United States agriculture.” The proposed research project supports this vision by providing the technology to produce high quality wheat-free food products from sorghum and fits under NP 306’s research component “new processes, new uses, and value-added foods and biobased products.” Production of high quality sorghum food products would represent a new market for sorghum; a market the National Grain Sorghum Producers Assoc. has estimated at $50 million/year. Worldwide, ~40% of sorghum is used for human food. As the U.S. annually exports 30-50% of its sorghum crop, technology that can improve the quality of sorghum based food products could lead to new and expanded export markets for U.S. sorghum and at the same time provide a healthy cereal food product for persons unable to eat wheat.


2.List the milestones (indicators of progress) from your Project Plan.
Objective 1: Determine relationships between sorghum grain physical properties including hardness, diameter, and kernel weight, protein and starch composition and processing quality. Year 1 - New slope and bias curves for measuring hardness, diameter, weight and moisture of sorghum grain by the SKCS will be determined for more accurate characterization of sorghum using the SKCS. - Differences in protein content and composition of isolated hard and soft endosperm fractions will be determined. - Sample sets to be used for relating processing quality to protein content and composition will be collected - Samples varying in pericarp color, presence of testa layer, plant color, and kernel attributes for analysis of grain color compounds, phenolics, and other small molecules will be collected. - Techniques for extracting and analyzing sorghum color compounds by HPLC and HPLC-MS will be developed.

Years 2 and 3 - Multi-instrument SKCS comparisons and calibrations with researchers in Kansas, Nebraska, and Texas will be completed. - The effect of environment on protein content and composition of isolated hard and soft endosperm fractions will be determined. - Wet milling, dry milling, extrusion and fermentation quality of selected sorghum lines will be conducted. - Color compounds, phenolics, and other small molecules in sorghum from weathered and sound grain; evaluate grains for markers of insect and fungal damage and infestation will be characterized and cataloged.

Years 4 and 5 - Exotic germplasm will be evaluated for desirable processing traits (e.g. ethanol yield). - GxE stability of processing quality in sorghum lines showing desirable processing traits will be evaluated. - Impact of compounds found in sorghum grains as a result of weathering, mold, insects, or fungal invasion on food and processing quality will be determined. - Processing methods to reduce or eliminate impact of environmental damage will be investigated.

Objective 2: Identify sorghum biochemical components related to food functionality and bio-industrial uses such as ethanol production. Use knowledge of these components to improve the quality and yields of bio-industrial materials and the quality and functionality of sorghum flour which will facilitate development of new, high quality foods, especially for the gluten free food market.

Year 1 - Improved techniques for extracting and analyzing sorghum proteins will be developed. - Methods for extracting and purifying sorghum proteins for industrial and food applications will be determined. - Formulations for the production of wheat free sorghum foods from batter type systems will be optimized.

Years 2 and 3 - Optimization of batter type product formulations for production of wheat free sorghum based foods will be continued. - Visco-elastic dough formation in artificial sorghum protein-starch dough systems will be investigated and changes to sorghum proteins during mixing will be elucidated and compared to wheat proteins during mixing. - Methods for disruption of sorghum protein bodies in sorghum flour to free proteins for interaction during mixing will be developed. - Starch and protein content and composition from diverse sorghum lines will be determined and related to ethanol and lactic acid yields. Years 4 and 5 - The extent of protein-protein interaction and protein-starch interaction in artificial sorghum dough systems will be determined. - Methods for the use of reduction-oxidation systems to form a visco-elastic dough directly from sorghum flour will be developed. - Sorghum proteins and starch will be modified to improve functionality in food. - Pre-treatment methods for altering protein and starch composition in sorghum for improved ethanol and lactic acid yields will be developed.


4a.What was the single most significant accomplishment this past year?
Identification of color compounds in sorghum and relation to weathering. Concentrations of six 3-deoxyanthocyanidins (apigeninidin, luteolinidin, plus their 5-O- and 7-O-methyl derivatives) and two flavones (apigenin and luteolin) were determined in samples of sorghum grain and glumes from purple- and tan-plant hybrids with varying degrees of moldiness. In grain from purple plants, concentrations of certain 3-deoxyanthocyanidins were high in samples with high ergosterol content, indicating that mold invasion greatly enhanced production of these compounds. Concentrations of 3-deoxyanthocyanidins in grain and glumes from purple plants were generally much higher than those from tan plants. Compared to grain, glumes had high degree of moldiness, high concentrations of 3-deoxyanthocyanidins or flavones, and different relative amounts of compounds. Because grain and glumes from the same hybrid had different relative concentrations among the six 3-deoxyanthocyanidins, it appeared that the compounds were produced in the grain and glume tissues where damage occurred as opposed to being transferred from one location to another such as from glumes to grain during exposure to precipitation. Ergosterol and 3-deoxyanthocyanidin levels were high in bran, which was consistent with highest mold levels usually occurring in the outer portion of the seed. This research provides information on the role of color compounds in the weathering a sorghum hybrids. This is especially important in white sorghums, where weathering causes off colors and flavors. Understanding the role of color compounds should help in the development of improved white sorghum lines, which would benefit sorghum producers, the sorghum food industry, and persons with celiac disease.


4b.List other significant accomplishments, if any.
We investigated the effect of decortication as a pretreatment method on ethanol production from sorghum as well as its impact on distiller’s dry grains with solubles (DDGS) quality. Eight sorghum hybrids with 0, 10, and 20% of their outer layer removed were used as raw materials for ethanol production. The decorticated samples were fermented to ethanol by using Saccharomyces cerevisiae. In general, decortication decreased the protein content of the samples up to 12% and increased starch content by 5 to 15%. Fiber content was decreased by 50 to 90%. These changes allowed for a higher starch loading for ethanol fermentation and resulted in increased ethanol production. Ethanol yields increased 3 to 11% for the 10% decorticated sorghum and 8 to 18% for the 20% decorticated sorghum. Using decorticated grain increased the protein content of DDGS by 11 to 39% and lowered fiber content 22 to 55%. Using decorticated sorghum may be beneficial for ethanol plants as ethanol yield increases and feeding quality of the DDGS is improved.


5.Describe the major accomplishments over the life of the project, including their predicted or actual impact.
To date the major accomplishments of this research project have been relating the biochemical composition of sorghum grain to the production of fuel ethanol. We have studied the effect of genetic x environmental interactions and found that both factors contribute to fermentation yields. This means that sorghum lines with higher fermentation potential can be identified. We have found methods for improving the ethanol yields from sorghum by pre-treating the sorghum through the use of extrusion processing and decortication. This research may have impacts as the fuel ethanol industry moves into the traditional sorghum growing regions of the U.S. It will also enable us to work with sorghum breeders to improve the inherent genetic potential for increased fuel ethanol yields.


6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products?
To date the results of this research project have been published in peer reviewed scientific journals and presented at two national meetings. Information has also been transmitted via one on one interactions with other members of the scientific community, persons in the celiac community, and persons in the sorghum industry.


7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below).
Young, Audrey. 2005. Milo is missing a marked ingredient. Kansas Farmer January, pg 7.


Review Publications
Schober, T., Messerschmidt, M., Bean, S., Park, S.H., Arendt, E.K. 2005. Gluten-free bread from sorghum: quality differences among hybrids. Cereal Chemistry. 82(4): 394-404.

Razote, E.B., Maghirang, R.G., Seitz, L.M., Jeon, I.J. 2004. Characterization of volatile organic compounds on airborne dust in a swine finishing barn. Transactions of the ASAE. 47:1231-1238.

Schober, T., Bean, S., Messerschmidt, M., Park, S., Arendt, E.K. 2005. Wheat-free breads from sorghum: quality differences among hybrids. Proceedings of the 24th Biennial Grain Sorghum Research & Utilization Conference. Meeting Abstract. p. 36.

Corredor, D., Bean, S., Schober, T., Wang, D. 2005. Effect of decorticated sorghum on ethanol production and chemical composition of DDGS. Proceedings of the 24th Biennial Grain Sorghum Research & Utilization Conference. Meeting Abstract. p. 33.

Schober, T., Bean, S., Kuhn, M. 2005. Classification of spelt cultivars based on their functional gluten properties. Third International Wheat Quality Conference Proceedings. Meeting Abstract. p.391

Singh, H., Park, S., Bean, S. 2005. Optimization of lab-scale production of sorghum waffles. Proceedings of the 24th Biennial Grain Sorghum Research & Utilization Conference. Meeting Abstract. p. 34.

Seitz, L.M. 2005. Effect of plant-type (purple vs. tan) and mold invasion on concentrations of 3-deoxyanthocyanidins in sorghum grain. Proceedings of the 24th Biennial Grain Sorghum Research & Utilization Conference. Meeting Abstract. p. 29.

Last Modified: 9/10/2014
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