Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2001
Publication Date: 9/16/2001
Citation: Foulk, J.A., Bunn, J.M. Physical and barrier properties of developed bilayer protein films. Applied Engineering in Agriculture. 2001. v. 17 (5). p 635-641.
Interpretive Summary: In the last several years, considerable research has centered around the idea of using edible protein films and other biopolymers to produce a more environmentally friendly film. Demand for biodegradable polymers produced from renewable natural resources has grown as environmental concerns increase. Multilayer films of different proteins may have improved properties over single layer protein films. Previous films were constructed with a structural layer for mechanical support and a lipid layer to enhance barrier properties. This research provides the first work performed on pure protein bilayer film production. Depending upon film type in this study, pure protein bilayer films exhibited reduced, similar, and enhanced properties. U. S. farmers and biopolymer markets are interested because use of renewable natural resources could aid U. S. based farms and industries.
Technical Abstract: Previously, bilayer films were constructed with a structural and lipid layer so that multilayer films containing only proteins could demonstrate improved properties over lipid films and other single layer protein films. This study was conducted to determine whether bilayer protein films could be produced, and to compare barrier and physical properties of these films to single layer films from the same base materials. The effects of three bilayer forming methods (liquid protein spread on dry film, heat pressing dry films, and solvent laminating dry films) on physical and barrier properties were investigated. These bilayer films were generated using soy protein isolate, wheat gluten protein, and corn zein protein. Bilayer films were evaluated for enhanced properties (tensile strength, percent elongation, water vapor and oxygen permeability) over single layer films. Using X-ray crystallography, these films showed no changes in degree of crystallinity. Depending upon film type in this study, protein bilayer films exhibited reduced, similar, and enhanced properties. Hydration properties, solvent and protein interactions, film thickness, surface properties, or heat and pH differences influenced the formation of these films. Water vapor permeability for these films ranged from 1.3x10**9 g m **1 s**1Pa**1 for soy sprayed on corn film to 3.5x10**9 g m**1 s**1 Pa**1 for solvent laminating wheat and soy films. Oxygen permeability ranged from 1.19x10**17 moles m m**2 s**1Pa**1 for pouring wheat on corn films to 9.16x10**18 moles m m**2 s**1 Pa**1 for heat pressing wheat and corn films. Tensile strength ranged from 1.57 MPa for spraying corn on wheat films to 11.69 MPa for pouring wheat on soy films. Elongation ranged from 5.36% for pouring soy on corn films to 206.24% for pouring soy on wheat films.