100B-33 |
Heat curing of wheat gluten gliadin and glutenin films |
P. HERNANDEZ-MUŅOZ and R. J. Hernandez. School of Packaging, Michigan State University, East Lansing, MI 48824 It is well known that gluten undergoes cross-linking during heating through sulphydryl-disulphide interchange reactions. It has been shown that heat treatment of films made from gluten improved mechanical and moisture barrier properties but heat treatment of films made from gliadin and glutenin gluten fraction proteins has not been yet reported. The objective of this work was to evaluate the mechanical, color and water vapor barrier properties of gliadin and glutenin films heat-cured between 40EC and 95EC. Gliadin and glutenin fraction proteins were extracted from wheat gluten by ethanol solutions at selected pH values and cast into films. Films were heat cured at 40ēC, 55ēC, 70ēC, 85 ēC and 95 ēC for 24 hours in a dry oven. The effect of heat curing on color, moisture content, film weight loss in water, water vapor permeability, tensile strength, and elongation was evaluated and compared to untreated control films. All measurements were performed at 23ēC and 50% RH. Properties of films were more affected in the range of 55ēC to 70ēC. Properties were changed as follows: Tensile strength of gliadins increased 1500% and 270% for glutenin films; elongation decreased more for gliadins than for glutenin films; water vapor permeability decreased by a factor about 3; moisture content at 50% RH also decreased. Integrity of gliadin films in liquid water improved dramatically with heat treatment above 70ēC. Heat-cured films developed a yellowish color and got darker than control films with temperature increase. The heat treatment of gliadin and glutenin films strongly modified their barrier and physical properties. Heat treatment can be effectively used to optimize the use and application of these films.
Session 100B, Food Packaging
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