Date of this Version
Films were prepared by casting and drying alkaline aqueous film-forming solutions of soy protein isolate (SPI). Four additional types of films were made by combining SPI with poly(ethylene oxide) (PEO) in SPI to PEO ratios of 19:1, 9:1, 4:1, and 1.5:1 (w/w). Glycerin was added to all film-forming solutions as a plasticizer at 60% of total solid weight. Addition of PEO decreased film tensile strength (TS) and increased elongation at break (E). TS values ranged from 1.4 to 3.9 MPa and E values ranged from 83 to 152%. Water vapor permeability of the films ranged from 3.0 x 10-9 to 4.0 x 10-9 g/m∙sec∙Pa. Scanning electron micrographs of film cross sections showed an increase in the inferior texture with increasing amounts of PEO in the films.