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United States Department of Agriculture

Agricultural Research Service


Location: Cereal Crops Research

2008 Annual Report

1a.Objectives (from AD-416)
To contribute to the improvement of oat quality by characterizing panicle and kernel structure characteristics associated with environmental stability of high test weight, by determining kernel structure characteristics associated with improved milling yield, and by the characterization of genotypic and environmental effects on the chemical composition of polar lipids in oat groats.

1b.Approach (from AD-416)
In order to determine panicle and kernel structure effects on environmental stability of test weight, fifty advanced lines of oats will be selected from an oat breeding program in North Dakota. Selected lines will have high potential for high test weight and will be highly variable for panicle size. Lines will be grown in four diverse environments and intact panicles will be harvested. Panicle and kernel size and structure will be analyzed along with test weight to determine physical characteristics that provide high test weight even in harsh environments that adversely affect yield. Kernel structure associated with improved milling yield will be determined by dehulling different genotypes of oats with an impact dehuller, similar to dehullers used by industry. Every oats sample will be fractionated by kernel size by three different mechanisms that divide according to different size characteristics. Slotted sieves will separate according to kernel width, disc separators will separate according to kernel length, and a gravity table will separate according to kernel density. Each size fraction will be dehulled at a series of dehuller rotor speeds, so that the influence of different kernel size characteristics on dehulling efficiency and milling yield can be determined. Finally, oat polar lipids will be characterized from a variety of oat cultivars grown in diverse environments. Polar oat lipids will be extracted and analyzed for their chemical composition by chloroform/methanol/water extraction, separation by silica gel chromatography, and analyzed by high pressure liquid chromatography using an evaporative light scattering detector.

3.Progress Report
Most efforts were directed into data analysis and manuscript preparation. Laboratory work concentrated on development of methodology for the analysis of environmental effects on physicochemical properties of beta-glucan in oats. We have been optimizing extraction of soluble beta-glucan, chromatographic analysis of molecular weight, viscosity analyses, and methods for the analysis of the chemical fine structure of the polymer. This work aligns with NP306 Component 1: Quality Characterization, Preservation, and Enhancement.

1. Relationships between Oat Test Weight and Groat Proportion: Test weight and groat proportion are the two most important quality characteristics of oats which determine the value of the grain, yet a complete understanding of their relationship has been lacking. Test weight, also called bulk density, is the weight of grain that fits into a specified volume. Groat proportion is the mass proportion of the groat to the grain after the hull has been removed. We have derived theoretical relationships between these characteristics, based on kernel density components and grain packing characteristics, and tested these with values obtained with our newly developed sand displacement technology. The precise definition of the relationship between test weight and groat percentage allows industry to more accurately access the value of oats to be purchased for their particular process. This accomplishment aligns with NP306 Component 1: Quality Characterization, Preservation, and Enhancement.

2. Identification of Galactolipid Estolides in Oat Kernels: Galactolipids have value-added potential as lipid-soluble pharmaceutical carriers. Oats are one of the richest of all biological sources for galactolipids, but these galactolipids are not well-characterized. Our characterization has identified mono-, di-, tri-, and tetra galactolipids and their natural estolides, where one, two or three additional fatty acids are esterified to primary fatty acids at a hydroxyl group. This work more accurately defines the composition of polar oat oil preparations currently being marketed by some companies. This accomplishment aligns with NP306 Component 1: Quality Characterization, Preservation, and Enhancement.

3. Control of Antioxidant Concentration in Oat Kernels: Most of the antioxidant activity in oat kernels is associated with a group of compounds called the avenanthramides increasing the concentration could be of significant nutritional interest because of possible health benefits. We have found that oats grown in environments where they are exposed to the plant disease known as crown rust have up to 20 times more of these avenanthramides than environments free of crown rust. Also in those environments, the antioxidant concentration was positively correlated with the genetic resistance present in the particular oat variety. Thus, it appears necessary to expose crown rust-resistant oat varieties to the disease in order to get high antioxidant concentration in oat kernels. This indicates that industries interested is marketing oat antioxidants must obtain grain from cultivars with high crown rust resistance, grown in environments where they are exposed to the disease. This accomplishment aligns with NP306 Component 1: Quality Characterization, Preservation, and Enhancement.

5.Significant Activities that Support Special Target Populations
Oats are more commonly grown by smaller farms. This project contributes to the development and release of new oat cultivars through the North Dakota State University Oat Improvement Program. We have been particularly active in the selection of high fiber cultivars, such as “HiFi”, which provide greater health benefits to consumers and more value to the producers.

6.Technology Transfer


Review Publications
Doehlert, D.C., Jannink, J., Mcmullen, M.S. 2008. Size distributions of different orders of kernels within the oat spikelet. Crop Science. 48:298-340

Moreau, R.A., Doehlert, D.C., Welti, R., Isaac, G., Roth, M., Tamura, P., Nunez, A. 2008. The identification of mono-, di-, tri-, and tetragalactosyl-diacylglycerols and their natural estolides in oat kernels. Lipids. 43:533-548.

Last Modified: 4/16/2014
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