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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVED UTILIZATION OF PROTEINACEOUS CROP CO-PRODUCTS AND RESIDUES

Location: Plant Polymer Research

2012 Annual Report


1a. Objectives (from AD-416):
The long-term objective of this project is to develop novel products utilizing current and new co-products from the industrial processing of agricultural materials. By accomplishing this, our research will reduce dependence on non-renewable materials and produce higher value products that will benefit a large segment of our economy. Objective 1: Develop technologies that enable commercially viable biobased materials from the proteinaceous co-products produced during cereal and soy processing. Objective 2: Develop novel extraction techniques that enable the commercially viable biorefining of new protein-rich industrial feedstocks such as alfalfa and pennycress.


1b. Approach (from AD-416):
Improve extraction, isolation, and derivatization techniques; develop new routes to isolate and characterize proteinaceous materials from corn, soy, pennycress, and alfalfa. Proteins will need to be physically or chemically modified in solution and in melt state in order to impart valued properties required for the desired applications.


3. Progress Report:
The use of ultrafiltration-diafiltration (UF-DF) in purifying corn germ protein has continued. The wet milled germ was reduced to 0.4 mm before extraction. This reduction gave higher protein extraction (40%) relative to previous techniques (~27%). Purity of the extract improved from 30 to 40%. The UF-DF protein extract was more soluble (50%) than acid-precipitated (AP) protein (30%). Surprisingly the UF-DF protein had the same solubility in acidic, neutral, and alkaline conditions. This enhanced solubility brings higher value. The protein was a better emulsifier than protein recovered by our baseline method. We anticipate that other UF-DF properties, such as foaming, will also be improved. Emulsification and foaming properties are important in products such as paints, shaving foams, and facial creams. Extraction of proteins from alfalfa leaves and stems using various solvents was performed. Water-soluble protein was the dominant fraction (40%), while saline-soluble protein had the least amount (3%). For pennycress seed, we compared traditional acid-precipitated and saline extraction (SE) to extract protein. SE gave higher protein extraction (40% vs. 34%), but both produced pennycress protein of high purity (90%). Pennycress protein is highly soluble in acidic (68%), neutral (74%), and alkaline media (90%), has good foaming and emulsifying ability. We have evaluated impact of nine salts with differing capabilities of interacting with proteins on zein properties. We found that these salts act as plasticizers. Guanidine thiocyanate gave higher elongations than control while magnesium thiocyanate gave zein articles with lower elongation. As elongation is increased, tensile strength decreases. The use of these salts in zein formulations with high tensile strength but low elongation did not result in improved elongation. The use of anhydrides to modify zein (in solution and melt) and soy (solution only) proteins has been studied. The modification of soy has been hampered by insolubility. Zein has been modified by acetic anhydride (Ac2O) and poly(ethylenemaleic anhydride). Solutions of zein modified with Ac2O can be electrospun to give fiber mats composed of a mix of round and ribbon fibers. Value in use is in progress. Historically zein has been used in the textile fiber market and re-introduction into this market will require additional fundamental knowledge. While acetic acid (AcOH) and 90% ethanol-water (EtOH-H2O) have both been shown to provide electrospun fibers, mixtures of these solvents have not been studied. In AcOH the 1.0 micron fibers are round while in EtOH-H2O the 4 micron fibers are ribbons. The change in fiber structure occurs at 30% AcOH/70% EtOH-H2O. The sample viscosity begins to increase significantly at this point. Efforts are in progress to understand what other solution properties may be changing with these solvent changes.


4. Accomplishments


Review Publications
Selling, G.W. 2012. Electrospun fiber and cast films produced using zein blends with nylon-6. Journal of Applied Polymer Science. 123(5):2651-2661.

Last Modified: 10/16/2017
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