Biological Systems Engineering


Date of this Version



Published in Cereal Chemistry Vol. 72, No. 6, 1995. Copyright 1995 American Association of Cereal Chemists, Inc. Used by permission.


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.