|Lawton Jr, John|
Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2003
Publication Date: 10/19/2004
Citation: Kim, S., Sessa, D.J., Lawton Jr., J.W. 2004. Characterization of zein modified with a mild cross-linking agent. Industrial Crops and Products. 20:291-300. Interpretive Summary: Corn is an abundant renewable resource that was used to produce nearly 2 billion gallons of ethanol in 2002. To make its production economically feasible with less reliance on government subsidy, the co-products of its manufacture must be better utilized. About 45% of the ethanol produced is generated by wet milling where corn gluten meal, a co-product of that process, is used to generate 500 metric tons of zein per year. Zein forms films which are brittle. To enhance the film forming mechanical properties we evaluated a mild cross-linking agent which investigation involves showing the cross-linking mechanism, optimizing the reaction conditions, characterizing the reaction product and measuring the mechanical properties of cross-linked zein film. These basic findings are essential to better understand the principles necessary to generate improved zein films. This information should be useful to scientists in industry, academia and government who are interested in expanding new film forming uses of zein.
Technical Abstract: Zein, a predominant corn protein, is an alcohol-soluble protein extracted from corn and is an excellent film former. The characteristic brittleness of zein diminishes its usefulness as a film. It is well known that zein has a propensity for forming aggregates in solution. When zein molecules were cross-linked with EDC (1-[3-dimethylaminopropyl]-3-ethyl-carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide), it was found that the film-forming property was improved and the aggregation phenomenon in solution was supressed. At the air/water interface, native zein forms brittle film with rough surface while cross-linked zein forms rigid film with very smooth and even surface. Tensile strength of the films were shown to be greatly increased by cross-linking. Through viscosity and dynamic light scattering, the cross-linking reaction was monitored. Optimum amount of EDC & NHS was determined to be 30mg each per gram of zein. The cross-linking of zein with EDC & NHS seemed to be self-terminating since the cross-linking reaction did not proceed to precipitation.