Sample Preparation and testing Methods Affect the Physical Properties and Evaluation of Plasticized Zein

Authors: Selling, Gordon; Sessa, David

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2006
Publication Date: 2/5/2007
Citation: Selling, G.W., Sessa, D.J. 2007. Sample Preparation and testing Methods Affect the Physical Properties and Evaluation of Plasticized Zein. Industrial Crops and Products. 25(3):266-273.

Interpretive Summary: Zein, the predominant protein in corn, is a major co-product of the bio-ethanol industry. Efforts are underway to isolate this material cost-effectively. Research is being conducted by various research groups to produce extruded films utilizing zein in order to improve the economics of the bio-ethanol industry. When films are produced using extrusion techniques, their physical properties may be dependent on the direction in which they are tested. The two principal directions are called the machine direction (MD, the direction in which the material is being produced) and the transverse direction (TD, the direction perpendicular to that in which the material is being produced). If the MD and TD properties are significantly different, then the film may not be acceptable in certain markets. In order to reduce the property differences in a commercial environment, additional equipment would be required to further treat the film. To date, no work has been published detailing whether extruded zein has different physical properties when measured in these directions. It was found that physical properties are different when measured in these two directions. This research is important as it will guide future work in the area of producing zein based films and define whether additional investment may be required in a commercial operation. This information will be useful to scientists in industry, academia and government who are interested in zein processing and products.

Technical Abstract: Physical properties were measured on extruded zein ribbon samples in both the machine and transverse directions. Tensile strengths and elongations were higher in the machine direction. Tensile strengths were comparable between un-oriented compression molded zein samples and extruded ribbons. However, the compression molded samples had much higher elongations. Polarized IR spectra of zein ribbons displayed small differences between the spectra taken in the machine direction versus the transverse direction. These results demonstrate that zein undergoes orientation during extrusion and that orientation impacts physical properties.