Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/11/2005
Publication Date: 12/22/2005
Citation: Pallos, F.M., Robertson, G.H., Pavlath, A.E., Orts, W.J. 2006. Thermo-formed wheat gluten protein biopolymers. Journal of Agricultural and Food Chemistry. 54:349-52. Interpretive Summary: Wheat is grown in large surplus in the United States. Together with declining exports there has emerged a growing need for finding new uses for wheat and its fractions. Refined wheat yields both starch and protein, and the latter has been largely limited to food applications. This paper describes research to create new polymeric forms for wheat and to quantify elastic properties thereof in comparison to those of commercial derived from petro chemicals polymers. High temperature, pressure, and chemical crosslinking were successful in producing an elastic, translucent polymer in sheet form. With modification to improve moisture resistance this material could functionally replace commodity, synthetic in specialized packaging applications.
Technical Abstract: Wheat gluten is a protein platform chemical potentially available in large quantitites that would exceed current food use markets. Thermoforming is one alternative technical means for transforming wheat gluten to polymeric forms. Thermoforming was applied here to wheat gluten under chemically reductive conditions to form pliable, translucent sheets. A wide variety of conditions, i.e., temperature, reducing agents, plasticizers and additives were tested to obtain a range of elastic properties in the thermoformed sheets. These properties were compared to those of commercially available polymers, such as polypropylene. Elasticity of the gluten formulations were indexed by Young's modulus and were in the range measured for commercial products when tested in the 30-70% relative humidity range. Removal of the gliadin subfraction of gluten yielded polymers with higher Young's modulus since this component acts as a polymer-chain terminator. At relative humidity less than 30% all whole gluten-based sheets were brittle, while above 70% they were highly elastic.