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Characterization of biodegradable films obtained from cysteine-mediated polymerized gliadins

Hernandez-Munoz, P., Kanavouras, A., Villalobos, R., Chiralt, A.
Journal of agricultural and food chemistry 2004 v.52 no.26 pp. 7897-7904
gliadin, polymerization, crosslinking, cysteine, biodegradable products, films (materials), disulfide bonds, packaging materials, mechanical properties, glass transition temperature, tensile strength, ethanol, solubility, thermal properties
This study focuses on the effect exerted by interchain disulfide bonds on the functional properties of films made from gliadins when cross-linked with cysteine. Gliadins were extracted from commercial wheat gluten with 70% aqueous ethanol, and cysteine was added to the film-forming solution to promote cross-linking between protein chains. The formation of interchain disulfide bonds was assessed by SDS-PAGE analysis. Gliadin films treated with cysteine maintain their integrity in water and become less extensible while their tensile strength increases as a consequence of the development of a more rigid network. The glass transition temperature of cross-linked films shifts to slightly higher values. The plasticizing effects of glycerol and moisture are also demonstrated. The mechanical behavior of cysteine-cross-linked gliadin films was compared to that of polymeric glutenins. Cross-linked gliadins displayed tensile strength values similar to those of glutenin films but achieved slightly lower elongation values. Cysteine-cross-linked gliadin films present the advantage that they are ethanol soluble, facilitating film fabrication or their application as a coating for food or for any other film or surface.