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United States Department of Agriculture

Agricultural Research Service


Location: Plant Polymer Research

2009 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, such as zein, technological advancements are needed in the areas of isolation, purification and products. We had found the optimal conditions for using cellulase or protease during the extraction of corn germ proteins. Extraction efficiency and chemical/functional properties of the protein products were determined. The use of enzyme more than doubled the protein yield and improved the functional properties of the recovered protein. Foaming properties and water-holding capacity were satisfactory and not adversely affected by the presence of enzyme. Efforts have been expended on transferring our zein purification technology from the lab to the pilot plant. Experiments were carried out using a series of zeolites and activated carbons to select column packings in order to minimize the adsorption of protein and reduce impurities. Centrifugation for the lab-scale process and a bag filtration for the pilot operation were essential to limit zein gelling/aggregation. We adapted use of an atomizer spray head and low heat for pilot plant spray drying to minimize protein denaturation. Resin composites generated from zein solutions or zein melt-processed with a series of lipid, chitosan, nanomaterials, nylon 6, urea (a protein denaturant and plasticizer) were evaluated for their impact on properties. Some of the resulting composites show enhanced stiffness with excellent tensile strength, but ductility is still an issue. Rheological studies have been carried out on the reaction of zein with formaldehyde or glyoxal. The reaction in acetic acid of formaldehyde with zein was 10x faster than glyoxal (exacerbated at lower temperatures). This is being attributed to the lower number of sites (3-5) present within zein that can react glyoxal versus those that can react with formaldehyde (>50). Initial studies have shown that by coating non-food contact paper with as-is zein in the range of 2 –25% by weight (solution dipping) the passage of liquid water is reduced by a factor of 2–50x. If the zein is first cross-linked with formaldehyde followed by heating, then the rate of liquid permeation decreases by a additional factor of 7 relative to the zein/formaldehyde control paper. We made final modifications to plywood glue formulations that contained soybean meal, corn germ, or sorghum flour, such that they contributed at least double the amount of protein than is present in standard sprayline glues. Our glues also had 10-15% less phenol-formaldehyde. The glues were applied to Southern pine veneers that were made into three-ply panels. These new glues had mixing properties and bond strengths that equaled that of the wheat-based industry glue. Through this work we have provided improved methods for isolation corn germ proteins, improved purification of zein, improved zein and cereal protein based products, and develop an improved understanding of the chemistry leading to improved zein based articles.

1. Production of durable zein articles. Improved water and solvent resistance is needed to provide zein based articles to the market. The first study has been carried out studying the rate of reaction of zein with two cross-linking reagents; cross-linking reduces the impact of solvents on properties. It has been found that formaldehyde is on the order of 10x faster than glyoxal in terms of its ability to cross-link zein at room temperature, with differences larger at reduced temperatures and in different solvents. This is the first research to clearly highlight the affect of temperature and solvent selection on the rate of reaction of zein with various reagents. Defining the length of time needed for a reaction to take place is essential for transferring the technology to industry.

2. Formulation of Soybean-, Corn-, and Sorghum-based Plywood Adhesives. More protein co-products from soybean and cereal processing are expected to be generated as a result of increased demands for biofuels. Soybean meal, corn germ and sorghum flour contain proteins with desirable functional properties, which were exploited in producing plywood glues. The glues with the alternative protein extenders had mixing properties and bonding strength that equaled that of the industry adhesive and are viable protein extenders in plywood glues. Efforts are underway to transfer this technology to industry which will have a beneficial economic impact for the plywood industry and soybean and corn farmers.

6.Technology Transfer

Number of Active CRADAs2
Number of the New/Active MTAs (providing only)4

Review Publications
Hojilla-Evangelista, M.P., Evangelista, R.L. 2009. Functional Properties of Protein from Lesquerella Fendleri Seed and Press Cake from Oil Processing. Industrial Crops and Products. 29(1):466-472.

Hojillaevangelist, M.P., Evangelista, R.L., Wu, Y.V. 2009. Characterization of Milkweed Seed Proteins. Industrial Crops and Products. 29(1):275-280.

Hojillaevangelist, M.P., Evangelista, R.L. 2009. Effects of Cooking and Screw-pressing on Functional Properties of Protein in Milkweed (Asclepias spp.) Seed Meals and Press Cakes. Industrial Crops and Products. 29(1)615-621.

Sessa, D.J., Mohamed, A., Byars, J.A. 2008. Chemistry and Physical Properties of Melt Processed- and Solution- Cross Linked Corn Zein. Journal of Agricultural and Food Chemistry. 56(1):7067-7075.

Selling, G.W., Woods, K.K., Biswas, A., Willett, J.L. 2009. Reactive Extrusion of Zein with Glyoxal. Journal of Applied Polymer Science. 113(3):1828-1835.

Last Modified: 4/16/2014
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