Development and property enhancement of bi-layer edible films produced from corn zein and methylcellulose

Water vapor permeability (WVP), tensile strength (TS), and elongation (E) were investigated in laminated methylcellulose/corn zein-fatty acid films. They were prepared by casting corn zein-fatty acid solutions onto methylcellulose films. WVP decreased as chain length and concentration of fatty acids increased. The TS of laminated edible film containing palmitic acid decreased as palmitic acid increased. The TS of films containing stearic-palmitic acid blends showed similar trends but there were not significant differences among blends. The TS of film containing lauric acid reached a maximum at 30% lauric acid concentration. The E values for films containing fatty acids varied inversely with TS.; Lipid content, migrated fatty acid concentration and oxygen permeability of laminated methylcellulose/corn zein-fatty acid films and methylcellulose films separated from the laminate were investigated. Total lipid content ranged from 0.5615 to 15677 g/cm{dollar}sp3{dollar} for the entire laminated edible film structure and the migrated fatty acid ranged from 0.6199 to 2.1995 g/cm{dollar}sp3{dollar} in the methylcellulose layer. Fatty acid migration increased with chain length and fatty acid concentration. Oxygen permeabilities of both laminated methylcellulose/corn zein-fatty acid films and methylcellulose films separated from the laminate increased as the chain length of fatty acid decreased and concentration of fatty acid increased. Scanning electron microscopy (SEM) and soxhlet extraction revealed migration of fatty acids from the corn zein layer into and through the methylcellulose layer. Surface morphologies of laminated films were studied using SEM.; Laminated edible films were used for potato chip packaging. The effects of stearic-palmitic acid blend concentrations in the film, storage temperature and storage time on potato chip quality were evaluated using Response Surface Methodology. Storage temperature and time affected the quality of potato chips. The limit conditions of storage temperature and time for acceptable potato chip quality were: 15{dollar}spcirc{dollar}C-30 to 43 days, 25{dollar}spcirc{dollar}C-23 to 25 days, and 35{dollar}spcirc{dollar}C-11 to 12 days for all stearic-palmitic acid blend concentrations.