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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

2006 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? Why 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. Since 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 by year the currently approved milestones (indicators of research progress)
Objective 1: Determine relationships between sorghum grain physical properties including hardness, diameter, and kernel weight, protein and starch composition and processing quality. Year 1 (FY 2005) 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.

2. Differences in protein content and composition of isolated hard and soft endosperm fractions will be determined.

3. Sample sets to be used for relating processing quality to protein content and composition will be collected.

4. Samples varying in pericarp color, presence of testa layer, plant color, and other kernel attributes for analysis of grain color compounds, phenolics, and other small molecules will be collected.

5. Techniques for extracting and analyzing sorghum color compounds by HPLC and HPLC-MS will be developed.

Years 2 and 3 (FY 2006 & 2007) 1. Multi-instrument SKCS comparisons and calibrations with researchers in Kansas, Nebraska, and Texas will be completed.

2. The effect of environment on protein content and composition of isolated hard and soft endosperm fractions will be determined.

3. Wet milling, dry milling, extrusion and fermentation quality of selected sorghum lines will be conducted.

4. Color compounds, phenolics, and other small molecules in sorghum from weathered and sound grain; evaluate grains for markers of insect and fungal damage; infestation will be characterized and cataloged.

Years 4 and 5 (FY 2008 & 2009) 1. Exotic germplasm will be evaluated for desirable processing traits (e.g. ethanol yield).

2. GxE stability of processing quality in sorghum lines showing desirable processing traits will be evaluated.

3. 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.

4. 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 (FY2005) 1. Improved techniques for extracting and analyzing sorghum proteins will be developed.

2. Methods for extracting and purifying sorghum proteins for industrial and food applications will be determined.

3. Formulations for the production of wheat free sorghum foods from batter type systems will be optimized.

Years 2 and 3 (FY2006 & 2007) 1. Optimization of batter type product formulations for production of wheat free sorghum based foods will be continued.

2. 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.

3. Methods for disruption of sorghum protein bodies in sorghum flour to free proteins for interaction during mixing will be developed.

4. 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 (FY2008 & 2009) 1. The extent of protein-protein interaction and protein-starch interaction in artificial sorghum dough systems will be determined.

2. Methods for the use of reduction-oxidation systems to form a visco-elastic dough directly from sorghum flour will be developed.

3. Sorghum proteins and starch will be modified to improve functionality in food.

4. Pre-treatment methods for altering protein and starch composition in sorghum for improved ethanol and lactic acid yields will be developed.


4a.List the single most significant research accomplishment during FY 2006.
A method was developed to rapidly isolate starch from cereal grains using ultrasound. This method allowed the purification of starch from ground whole meal in 30 min, greatly reducing the time required to obtain starch for research. Isolated starch has been used in experiments to determine the role of starch chemistry on fermentation quality of cereal grains. High levels of amylose in starch were found to reduce fermentation quality and required special processing conditions to fully utilize.


4b.List other significant research accomplishment(s), if any.
Tannins from a diverse set of samples were characterized and their biological activity assayed. The molecular weight distribution of the tannins was found to be related to their anti-oxidant capacity and lines with highly active tannins were identified.


4c.List significant activities that support special target populations.
None.


5.Describe the major accomplishments to date and 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. Sorghum hybrids with improved fermentation quality have been identified. We have also found methods for improving the ethanol yield from sorghum by pre-treating the sorghum through the use of extrusion processing and decortication. The latest developments show that decortication improves ethanol yield up to 20% by allowing higher starch loading during fermentation. This research may have impact 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 yield.


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 interaction 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).
Schober, T. J., Bean, S. R., Arendt, E. K., and Fenster, C. Use of sorghum flour in bakery products. AIB Technical Bulletin. May/June 2006.


Review Publications
Bean, S., Chung, O.K., Tuinstra, M.R., Pedersen, J.F., Erpelding, J.E. 2006. Evaluation of the single kernel characterization system (SKCS) measurements of sorghum grain attributes. Cereal Chem. 83:108-113.

Chung, O.K., Bean, S.R., and Park, S.H. 2005. Sorghum foods: New health benefits from an ancient grain. Food Science Journal (Chinese) 25:431-437.

Corredor, D.Y., Bean, S.R., Schober, T.J., and Wang, D. 2006. Effect of decorticating sorghum on ethanol production and composition of DDGS. Cereal Chem. 83(1): 17-21.

Schober, T.J., Bean, S.R., and Kuhn, M. 2005. Protein composition and fundamental rheological properties of spelt cultivars as a model of gluten quality. Abstract No. 242 Page 145 in: Program Book of the 90th Annual Meeting of the AACC. [Abstract]

Corredor, D.Y., Bean, S.R., Schober, T.J., and Wang, D. 2005. Effect of decorticating sorghum on ethanol production and composition of distiller’s dry grain with solubles (DDGS). Abstract No. 274 Page 154 in: Program Book of the 90th Annual Meeting of the AACC. [Abstract]

Seitz, L.M. 2005. 3-deoxyanthocyanidins and other phenolic compounds in grain from sorghum sister lines with white, red, and yellow pericarp. Abstract No. 270 in: 2005 AACC Annual Meeting Program Book. p.153. Meeting Abstract.

Bean, S., Ioerger, B.P., Park, S.H., Singh, H. 2006. Interaction between sorghum protein extraction and precipitation conditions on the yield, purity, and composition of purified protein fractions. Cereal Chem. 83:99-107.

Wang, D., Wu, X., Bean, S., Wilson, J.P. 2006. Ethanol production from pearl millet by using Saccharomyces cerevisiae. Cereal Chemistry 83:127-131.

Zhan, X., Wang, D., Bean, S., Mo, X., Sun, X.S., Boyle, D. 2006. Evaluation of ethanol production from extrusion-cooked sorghum flour. Industrial Crops and Products. 23:304-310.

Last Modified: 4/18/2014
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