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United States Department of Agriculture

Agricultural Research Service

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Location: Plant Polymer Research

2010 Annual Report

1a.Objectives (from AD-416)
The primary goals for this project are to develop new chemistries and processes to enhance the utilization of co-products produced during cereal and soy processing, and bioethanol production thereby generating new markets for these co-products. The physical and chemical properties of the co-products will be characterized and their unique functional properties utilized to develop value added materials.

1b.Approach (from AD-416)
Characterize the structure and properties of zein to identify how zein fractions come together to form gels and aggregates. Characterize non-zein proteins from corn germ by-products of corn milling and identify potential applications. Investigate availability of chemically or enzymically functional groups by spectrofluorometry upon processing zein under heat and pressure as well as proteolyzing zein with enzymes such as trypsin, chymotrypsin and Alcalase.

3.Progress Report
In order to provide the market with products using renewable proteinaceous materials, technological advancements are needed in the areas of protein isolation, purification and development of improved products and methods to make them. Our studies demonstrated that the cellulase cocktail enzyme was more effective than the proteases in increasing protein extraction yields and improving the solubility of recovered protein from corn germ. Both groups of enzymes gave protein products that formed excellent and stable emulsions and generated substantial foam volumes. However, foam stabilities were poor. We demonstrated that our zein purification process removes beta zeins (sourced from DDG’s) that have the tendency to aggregate in aqueous ethanols. We devised a combination of analytical methods to define zein products with differing degrees of purity to target specific applications. Rheological studies have continued on the reactions of glyoxal and formaldehyde with zein in acetic acid or ethanol/water. The apparent energy of activation for the reaction of glyoxal and formaldehyde with zein to produce a gel was determined. The modulus of the gel produced from the reaction of glyoxal is ~ 100x higher than similar formaldehyde formulations. This was attributed to the fact that each glyoxal molecule can bond up to four protein molecules and glyoxal does not self-polymerize. Initial electrospinning studies using formaldehyde and glyoxal in acetic acid have demonstrated that this system provides fibers with improved solvent resistance. While the reaction of glyoxal with zein is slow, when using the appropriate amount of glyoxal (6%), the resulting fibers have reasonable solvent resistance without an additional thermal treatment. Given the rate of the zein-glyoxal reaction, the impact of time on fiber morphology could be studied. At lower reaction times (lower solution viscosity) fibers were < 4 microns (~ to control); after six hours (increased viscosity) fiber diameter increases to >50 microns. The impact of extrusion processing on zein has been studied. Zein extrudates were produced at temperatures between 100 to 300 ºC. Using SDS-PAGE cross-linking could be seen at temperature above 120 ºC. Above 180 ºC, chain cleavage began to occur and was dominant at temperatures above 220 ºC. Above 160 ºC the color of the extrudate quickly begins to change. Other changes were also observed which will be useful in defining an extrusion processing box for zein. Melt processing of zein with polyvinylpyrrolidone (molecular weights tested were from 55K to 1.3M) forms a compatible blend based on thermal analyses and SEM findings. The mechanical properties of compression molded tensile bars showed moderate improvement. The combination of sorghum flour with ground soybean meal or corn germ meal had improved smoothness and viscosity relative to industrial standards or when soybean meal or corn germ meal were used alone as extender. The improved adhesive will be applied to veneers shortly to verify improvement in bonding.

1. Plywood Adhesive Formulation with Combined Sorghum and Soybean or Corn Germ as Extenders. Reducing the amount of animal based extenders in plywood glue will have a beneficial impact on the plywood industry. The use of soybean meal or corn germ meal based adhesives provides acceptable bonding, but further penetration into this market can be accomplished by providing a product with improved application properties. PPL Unit scientist at National Center for Agricultural Utilization Research in Peoria,IL, found that with the addition of sorghum flour, the adhesive application of these other plant based adhesives is improved. This research demonstrated that soybean meal, corn germ meal, and sorghum flour are viable protein extenders in plywood glues for sprayline coaters. Successful transfer of this technology to industry which generate enormous economic impact for both the plywood industry and soybean and corn farmers.

2. Production of improved zein fibers. Fully utilizing the co-products of bio-ethanol production will have a beneficial impact on this large segment of energy sector of our economy. PPL Unit scientist at National Center for Agricultural Utilization Research in Peoria,IL, developed a corn protein based fiber that is solvent resistant without additional heat treatments. Solvent resistance is important to provide a successful fiber in the textile market. They have found that by allowing zein to react with 6% glyoxal, the resulting fibers are durable to standard zein solvents without a thermal treatment. Successful scale-up and transfer of this technology will have a very large beneficial impact on the bio-ethanol industry.

Review Publications
Cheng, H.N., Dowd, M.K., Selling, G.W., Biswas, A. 2010. Synthesis of Cellulose Acetate from Cotton Byproducts. Carbohydrate Polymers. 80(2):499-452.

Last Modified: 4/18/2014
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