Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2009
Publication Date: 5/15/5009
Citation: Biswas, A., Selling, G.W., Woods, K.K., Evans, K.O. 2009. Surface modification of zein films. Industrial Crops and Products. 30(169):168-171.
Interpretive Summary: Zein is the main protein in corn kernels. It can be the major material in some of the co-products of the bio-ethanol industry. Currently these zein containing co-products are used in the animal-feed market. However, historically zein was used in higher value products. As early as the 1940’s it was commercially used in various wood or food coatings and fibers. The zein used in these markets had to be chemically modified in order to be less sensitive to moisture. The routes used previously would require significant investment to be performed safely today. In addition, the entire zein article was altered, where typically only the surface, which plays a major role in moisture absorption, needs to be altered. Techniques have now been developed that allow surface modification of zein films. After this modification the way the film interacts with water is changed. The zein film absorbs less moisture. These results will benefit those companies that are producing bio-ethanol in that one of their main co-products could be used in a higher value market.
Technical Abstract: A novel method to derivatize the surface of zein is devised that can modify the water absorption and surface wetting behavior. The reagents used to impart the desired properties in a reasonable amount of time include octenyl succinic anhydride and alkyl and alkenyl ketene dimers. The method is easy to apply and involves baking with an appropriate concentration of a derivatizing agent. Decreased water absorption and increased contact angle with water relative to control demonstrate the advantages this methodology provides. Atomic force microscopy was used to demonstrate that after derivatization the surface of the film became much different, having large globular domains that extended as much as 122 nm above the lowest surface. Given the hydrophobic character of the reagents and their relative incompatibility with zein, it was anticipated that derivatization would be somewhat inhomogeneous.