73D-36 |
Glutenin and gliadin films from wheat gluten: Preparation and properties |
P. HERNANDEZ-MUÑOZ and R. J. Hernandez. School of Packaging, Michigan State University, East Lansing, MI 48824 In the past edible films has been produced using wheat gluten. However, gluten is composed of two main groups of proteins: gliadin consisting of low molecular weight proteins, and glutenin containing high molecular weight proteins. The two fractions are in almost equal quantities and have similar amino acid composition. Preparing and characterizing films based on gliadins and glutenins is the focus of this study. The objective of this work was to developing edible films from different wheat gluten protein fractions and to study the effect of film composition on mechanical and barrier film properties. The glutenin and gliadin fractions utilized for this study were prepared from commercial gluten. The gliadin-rich fraction was extracted at room temperature with 70% (v./v.) aqueous ethanol solution at pH 6.4. The 70% ethanol-insoluble fraction (glutenin) was extracted with 50% (v./v.) aqueous ethanol solution and acetic acid (1%) at 60 °C. Gliadin and glutenin films were cast from film forming solutions. Glycerol was used as plasticizer. The films were dried in at 23 °C and 50% relative humidity (RH). The films obtained were transparent, glossy, and with a smooth surface. Glutenin formed stronger films than gliadin. The tensile strength increased in glutenin films while the elongation resulted lower than in gliadin films. Oxygen gas permeability (amol/m.s.Pa) at 0% RH and water vapor permeability (g/m.s.Pa) were measured at 23 °C. Glutenin films presented lower oxygen and water vapor permeability values [0.84±0.4 and 3.61±0.3, respectively] than gliadin films [0.97±0.2 and 5.02±0.5, respectively]. The high molecular weight glutenin films showed better mechanical and gas barrier properties than the gliadin films.
Session 73D, Food Packaging
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