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United States Department of Agriculture

Agricultural Research Service

2009 Annual Report

1a.Objectives (from AD-416)
Improve the functional properties of wheat, oat, and barley seed proteins by investigating isolation techniques, protein modification, and protein blends. Specific objectives include: (1) Develop cereal protein materials having specific and desirable characteristics, and determine the origin of the alterations occurring during the currently employed grain protein isolation methods. Initiate new protein materials with maximum functional properties. Determine the effect of commercially existing isolation methods on the functional properties of wheat, barley, and oat proteins; (2) Establish new and fundamental information on the physical, rheological, and mechanical properties of seed proteins that is of vital importance in developing new uses and new markets for seed proteins; and (3) Develop protein-based polymer blends from renewable resources to expand their utilization. The newly developed products will serve as alternatives to petroleum-based polymers.

1b.Approach (from AD-416)
Functional properties of isolated seed proteins will be evaluated and enhanced by chemical and enzymatic modification. Proteins will be characterized by field-flow fractionation, high performance liquid chromatography, capillary electrophoresis, thermal analysis, and ultracentrifugation. Rheological characterization of native and processed proteins will be made using a stress-controlled rheometer, a Diffusing Wave Spectrometer, and a newly developed Multiple Particle Tracking System. Blends of proteins with other polymers will be formulated for specific applications and their phase behavior, aggregation, and mechanical properties characterized.

3.Progress Report
One of the main components of the National Program 306 is to develop value added products from generally undervalued agricultural commodities. Newly developed products formulations from different grain proteins was the main scope of this project. Significant progress has been made on the isolation and modification of oat and barley proteins. The thermo-rheological properties of the isolated proteins were determined in addition to both linear and non-linear viscoelastic properties for oat and barley proteins. The thermo-rheological information of the isolated / characterized proteins was used in developing low carbohydrates / high proteins bread formulations. The isolated proteins will also be used in low-fat high-protein spoonable salad-dressing type of products. These products will be introduced as healthy products with a reasonable consumer acceptance, which will reduce the overall daily fat intake and increase the nutritional value of these products due to the high protein content.

On the non-food objectives of this project, various biodegradable composites with promising characteristics were developed. Different biodegradable composites were prepared using biodegradable polycaprolactone as the principle component blended with wheat gluten and other biomaterials. The developed composites showed promising results and potential for commercialization. The possibility of intermolecular interactions in crosslinked polyester/gluten and polyester/flour blends was explored by infrared analysis and the data was correlated with the thermal properties of the composites. The use of proteins and other biomaterials will increase biodegradability and reduce the need for synthetic polymers.

1. Enzymatic purification for oat proteins. Proteins isolation methods practiced today are damaging to functional properties of native proteins such as emulsification. New methods are needed to preserve their native structure. Oat proteins were isolated using three different enzymes. The method was based on enzymatically-degrading the carbohydrates of defatted oat flour. After filtration and drying, the remaining material had about 91% native protein. The analytical testing (thermal properties, electrophoresis, and HPLC) showed that the protein was not damaged during isolation. Preliminary testing showed that native oat protein has potential of replacing up to 50% of the total fat in some food products such as salad dressing. This information is very important because native proteins are proven to have broader range of applications and better functional properties.

2. Viscoelastic behavior of oat protein. Native and modified grain proteins are known to have unique functional properties. However, literature reports regarding oat-protein physico-chemical properties and processing behaviors are limited. In this work, both linear and non-linear viscoelastic properties for five kinds of oat proteins, acetylated oat proteins, transglutaminase crosslinked acetylated oat proteins, acid precipitated oat proteins, transglutaminase crosslinked acid precipitated oat proteins, and succinylated oat proteins, were determined. The outcome of this work provided more insight regarding oat protein structure-function properties relationship necessary for developing new food products and other applications. This will expand the utilization of these commodities.

3. A chemo-metric method for correcting infrared KBr spectra for water interference. Infrared is a good tool for measuring interactions between components in biomaterials. Infrared analysis of solid biopolymers by the KBr pellet technique is often frustrated by water interference in the important carbohydrate and protein regions of their spectra. A method was therefore devised that solves the problem and measures such spectra by mathematically eliminating the water interference. When used to correlate x-ray analyses and infrared spectra, this chemo-metric method makes analysis of complex three-dimensional structures in solid proteins and polysaccharides possible for the first time. This new spectral correction method represents a significant advance toward practical spectrometric analyses of solid biopolymers in nature. This will directly improve the understanding of protein structure, thus expands the understanding of the structure/function of grain proteins. This understanding will lead to further utilization.

4. Newly-developed particle-bonding technique and applications. Polymer blending is currently used to achieve specific properties, but binding these polymers is one of the challenges. It is demonstrated that the newly-developed particle-bonding technique can be used for production of composite materials from a variety of agricultural commodities, such as sugars, starch, buckwheat meal, salt, cocoa, milk powder, corn bran, etc. Best processing conditions were developed by varying several processing variables. The developed technique was applied to the making of conducting-polymer composites by the inclusion of conducting filler, graphite. Correlations among three factors, conductance, mechanical property, and composites compositions were tested. It was shown that the developed technique could be used for the production of microorganism pellets suitable for insect bio-control during silo storage. These new applications will expand the utilization of grain-proteins.

6.Technology Transfer


Review Publications
Mohamed, A., Biresaw, G., Xu, J., Hojillaevangelist, M.P., Rayas-Duarte, P. 2009. Oats Protein Isolate: Thermal, Rheological, Surface, and Functional Properties. Food Research International. 42(1):107-114.

Mohamed, A., Finkenstadt, V.L., Gordon, S.H., Biresaw, G., Palmquist, D.E., Rayas-Duarte, P. 2009. Thermal Properties of Extruded Injection-Molded Polycaprolactone/Gluten Bioblends Characterized by TGA, DSC, SEM and Infrared Photoacoustic Spectroscopy. Journal of Applied Polymer Science. 110(5):3256-3266.

Last Modified: 4/16/2014
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