Location: Grain Quality and Structure Research
2020 Annual Report
Objectives
Objective 1: Integrate commercial grain sorghum quality traits with the timing and duration of heat and/or drought stress during grain fill.
• Sub-Objective 1.A. Determine how timing of drought stress during grain fill impacts protein and starch chemistry and digestibility.
• Sub-Objective 1.B. Determine the degree to which heat stress impacts sorghum grain quality traits.
Objective 2: Enable new rapid/high-throughput commercial methods to measure grain sorghum composition and quality traits.
• Sub-Objective 2.A. Develop an in-vitro cellular antioxidant activity assay for measuring the efficacy of sorghum bioactive compounds in response to radical oxidative species.
• Sub-Objective 2.B. Determine the effectiveness of a blood glucometer in determining fermentation efficiency using sorghum grain.
Objective 3: Integrate the stability/variability of grain sorghum compositional quality and bionutrient components across multiple commercial production environments.
• Sub-Objective 3.A. Evaluate the variability in sorghum grain composition related to protein and starch across multiple growing environments.
• Sub-Objective 3.B. Characterize phytonutrient composition in tannin and black sorghum germplasm grown at multiple locations.
Objective 4: Molecular biological technologies will employ gene flow analysis to identify sorghum compositional and quality traits variants migrating through field/commercial sorghum breeding programs.
Approach
Sorghum [Sorghum bicolor (L.) Moench] is an important drought tolerant crop in regions of the Great Plains where water is limited and rainfall unpredictable. Sorghum has been primarily used for animal feed in the U.S. but recently has seen increasing use in the food and biofuel industries which has provided a new growth area for sorghum utilization. That said, there has not been extensive research conducted on grain quality factors related to sorghum. Recent advances have been made regarding improving sorghum protein and starch digestibility at the genetic level, yet little is known about how environmental factors impact sorghum grain quality attributes and nutritional bioavailability. Sorghum is typically grown under non-irrigated conditions and can face serious drought and heat stress during grain fill. Drought and heat stress may become more prevalent in sorghum growing regions due to climate change and have the potential to severely impact sorghum grain composition and end-use quality traits. Consistency is an important quality attribute of cereal crops and further research is required to quantify the degree to which sorghum grain quality is impacted by the environment. Our research will support on-going efforts to improve sorghum grain quality at the genetic level by providing grain quality information to breeding programs about the stability of various traits. We will provide knowledge of how drought and heat stress impacts sorghum grain quality, ultimately providing information necessary for the sorghum breeding community to improve the end-use quality of sorghum.
Progress Report
This project has completed its 5-year plan and this is the final summary report for this project cycle. A major project to address Objective 1 was completed by investigating changes to sorghum lines grown under drought stressed and heat-stressed conditions. Two sorghum lines that maintained grain composition under environmental stress conditions were identified in this research and could be useful in sorghum breeding programs aimed at mitigating the effect of stress on sorghum. Additional studies found that the environment had a large effect on kernel size and hardness as well as protein and starch properties. These studies also identified four sorghum lines that maintained good grain quality across environments and could be used in breeding programs. Collaborative research investigating changes to grain composition of staygreen and non- staygreen sorghum lines under drought stress found that staygreen sorghum lines had higher levels of protein and lower starch levels compared to non-staygreen lines. Limited irrigation was also found to impact sorghum grain composition and end-use quality. Results from this study showed average kernel weight, kernel diameter and test weight of grain sorghum increased as irrigation capacity increased, whereas kernel hardness index decreased as irrigation capacity increased. Irrigation capacity also had a positive impact on bioethanol yield. Additional environmental factors were studied such as soil chemistry and disease pressure were also studied for their impact on sorghum grain composition. This research identified one sorghum hybrid that had less negative impact on grain composition due to stalk rot which could be useful in developing disease resistant lines that maintain their nutritional quality under disease pressure. Studies investigating genetic diversity and sorghum grain composition in general were also carried out with studies identifying potential genes influencing carotenoid content in sorghum as well as other compositional traits related to Objective 3. Likewise, grain composition was measured for several sorghum germplasm releases, providing information to the sorghum breeding industry on grain composition of newly developed and released germplasm. Research related to Objective 2 was completed by improving the use of near infrared spectroscopy (NIR) for sorghum by investigating the role of grain moisture level on protein content determined by near infrared spectroscopy and statistical methods to treat data from weathered grains. Improvement of methods for extracting polymeric proteins from sorghum and extraction of polyphenols using solvents better suited to the food industry were investigated. Research was also conducted to support and enhance the utilization of sorghum including projects on using the novel ability of zein to form visco-elastic dough to enhance sorghum flour based breads; how sorghum tannins interacted with wheat gluten and influenced dough properties; the anti-cancer and anti-microbial properties of sorghum phenolic compounds; and how stored product insect pests thrived on sorghum flour milling fractions and how variability in sorghum grain composition influenced resistance to stored product insect pests.
Accomplishments
1. Sorghum polyphenols exhibit anti-microbial activity. Sorghum grain is known to have high levels of phenolic compounds that have many beneficial human health attributes. However, less is known about other benefits sorghum phenolic compounds may have. To further identify valuable properties of compounds in sorghum grain, ARS scientists in Manhattan, Kansas, in collaboration with researchers at Kansas State University, investigated the anti-microbial properties of extracts from sorghum grain. This research revealed that extracts from high polyphenol sorghum grain were able to reduce the growth of legionella infection inside mouse immune cells by activating specific immune signals. This study demonstrates the potential antimicrobial properties of sorghum phenolics and provides research to support new utilization of high polyphenol sorghum grain.
2. Combining proteins improves adhesive performance and reduces costs. Proteins can be used as adhesives to reduce the amount of formaldehyde used in the production of pressed wood products such as plywood. Probably the widest researched protein for adhesive use has been isolated soy proteins. While showing promise for use as adhesives, soy is a valuable food and feed ingredient and isolated soy proteins can be expensive for use as adhesives. As a simple and direct method to improve protein-based adhesives and reduce their cost, ARS scientists in Manhattan, Kansas, and collaborators at Kansas State University investigated the use of mixtures of sorghum, canola and soy proteins as adhesives. Using a mixture of these three proteins was found to improve adhesive performance substantially compared to using soy proteins alone. The optimum formula contained 50% soy and 50% sorghum – canola proteins, thus reducing the amount of soy protein needed. This in turn potentially reduced the cost of the adhesive and competition between food uses of soy and non-food uses. This research provides a simple and direct way to improve protein-based adhesives, while providing new avenues for utilization of proteins from other sources such as sorghum grain.
3. Insect feeding on sorghum flour milling fractions. It is well known that stored product insects can feed on wheat flour milling fractions and therefore thrive in flour mills. These insects can cause severe economic impact in flour mills and identifying flour milling fractions they can feed on is an important step in devising appropriate measures to control the insects. Due to the increasing interest in sorghum flour, it is possible this type of insects could also infest sorghum flour mills. To investigate this, ARS researchers in Manhattan, Kansas, along with collaborators at Kansas State University, monitored growth and development of the red flour beetle on six sorghum flour milling fractions. The red flour beetle survived and developed on all flour milling fractions, identifying that flour mill sanitation at all steps of sorghum flour milling would be critical in controlling this insect pest.
4. Sorghum varieties influence resistance to stored product insects. Stored product insects can cause severe economic damage by feeding on stored grains. Previous research has shown that the lesser grain borer survives well on stored sorghum grain. However, past research has been conducted on limited types of sorghum grain. Due to the increasing interest in various types of sorghum grain for human food uses, it would be valuable to know if different grain types vary in how well stored product insects can feed and survive on them. To address this question, ARS researchers in Manhattan, Kansas, tested four different sorghum varieties for resistance to the lesser grain borer. Insect production and feeding damage was generally lowest on the sorghum line with waxy starch. This research demonstrated that sorghum grain composition may influence resistance of sorghum to stored product insects.
5. Correction of near infrared spectrum to allow analysis of weathered sorghum grain. Sorghum grain grows in an exposed head on top of the sorghum plant. This type of growth allows the grain to be exposed to the elements and can result in the grain being damaged, often referred to as weathered grain. Weathered grain may be discolored and have altered chemical composition. Such changes to the grain impact the use of rapid, non-destructive near infrared (NIR) spectroscopic analysis for determining protein content. This in turn often means such samples are difficult to work with and analyze. To overcome this problem, ARS scientists in Manhattan, Kansas, along with collaborators at Kansas State University investigated the use of statistical methods to correct spectra from weathered grains when analyzed by NIR. Statistical corrections improved the accuracy of the NIR method and allowed for weathered grains to be analyzed and thus still useful in studies of sorghum grain composition.
6. Encapsulation of fish oil using sorghum protein particles. It is well known that fish oil contains nutrients important to human health. Despite the health benefits of fish oil, consumption remains low. One way to increase consumption of fish oil is by adding fish oil to other food products. Directly adding fish oil to other food products however can cause problems with off-flavors and off-odors. To overcome these issues, fish oils can be encapsulated within a shell that protects the fish oil from forming undesirable flavors and odors. ARS researchers in Manhattan, Kansas, collaborated with scientists at the University of Granada, Spain to investigate whether isolated sorghum grain proteins could be successfully used as the shell material to encapsulate fish oil. By using a technique called electrospraying, sorghum proteins were found to work very well at encapsulating fish oil and had an encapsulation efficiency of about 94%. This research shows the potential for sorghum proteins to be used as encapsulating agents for the food industry and opens new avenues and markets to increase the value of sorghum grain.
Review Publications
Girard, A.L., Bean, S.R., Tilley, M., Adrianos, S.L., Awika, J.M. 2017. Interaction mechanisms of condensed tannins (proanthocyanidins) with wheat gluten proteins. Food Chemistry. 245:1154-1162. https://doi.org/10.1016/j.foodchem.2017.11.054.
Pontieri, P., Troisi, J., Bean, S.R., Tilley, M., Di Salvo, M., Boffa, A., Pignon, D., Del Giudice, F., Alifano, P., Del Giudice, L. 2019. Comparison of methods for extracting Kafirin proteins from food-grade sorghum cultured in a Mediterranean environment. Australian Journal of Crop Science. 13:1297-1304. https://doi.org/10.21475/ajcs.19.13.08.p1695.
Arthur, F.H., Bean, S.R., Smolensky, D., Cox, S.R., Lin, H., Peiris, S., Petersen, J. 2020. Development of Rhyzopertha dominica (Coleoptera: Bostrychidae) on sorghum: quality characteristics and varietal susceptibility. Journal of Stored Products Research. https://doi.org/10.1016/j.jspr.2020.101569.
Bean, S.R., Zhu, L., Smith, B.M., Wilson, J.D., Ioerger, B.P., Tilley, M. 2018. Starch and protein chemistry and functional properties. In: J.R.N. Taylor and K. Duodu, editors. Sorghum and Millets: Chemistry and technology. 2nd edition. San Diego, CA: Elsevier. p. 131-170.
Liu, H., Bean, S.R., Sun, X. 2018. Camelina protein enhanced by polyelectrolyte interaction and its plywood bonding properties. Industrial Crops and Products. 124:343-352. https://doi.org/10.1016/j.indcrop.2018.07.068.
Ioerger, B.P., Bean, S.R., Tilley, M., Lin, H. 2020. An improved method for extraction of sorghum polymeric protein complexes. Journal of Cereal Science. https://doi.org/10.1016/j.jcs.2019.102876.
Peiris, K., Bean, S.R., Tilley, M., Jagadish, K. 2020. Analysis of sorghum content in corn-sorghum flour bioethanol feedstock by near infrared spectroscopy. Journal of Near Infrared Spectroscopy. https://doi.org/10.1177/0967033520924494.
Kaufman, R.C., Wilson, J.D., Bean, S.R., Galant, A.L., Perumal, R.R., Tesso, T., Herald, T.J., Shi, Y.C. 2018. Influence of genotype and environmental interaction on sorghum (Sorghum bicolor (L) Moench) grain chemistry and digestibility. Agronomy Journal. https://doi.org/10.2134/agronj2017.09.0561.
Xu, S., Shen, Y., Chen, G., Bean, S.R., Li, Y. 2019. Antioxidant characteristics and identification of peptides from sorghum kafirin hydrolysates. Journal of Food Science. 84:2065-2076. https://doi.org/10.1111/1750-3841.14704.
Gilchrist, A., Smolensky, D., Cox, S.R., Perumal, R., Noronha, L.E., Shames, S. 2020. High-polyphenol extracts from Sorghum bicolor attenuate replication of Legionella pneumophila within RAW 264.7 macrophages. FEMS Microbiology Letters. https://doi.org/10.1093/femsle/fnaa053.
