45D-29 |
Surface modification of poly(ethylene) film for active packaging applications |
M. D. STEVEN and J. H. Hotchkiss. Dept. of Food Science, Cornell Univ., 160 Stocking Hall, Ithaca, NY 14853-7201 Active packaging systems have many potential advantages over traditional packaging. These include antimicrobial effects and in-package processing. Current antimicrobial packaging technologies involve migration of the active compound from the packaging into the food; non-migratory systems are preferable due to negative consumer attitudes towards food additives. Modification of a polymer film surface was investigated as a method for the development of non-migratory active packaging systems from poly(ethylene), a readily available, low-cost polymer. Poly(ethylene) film was surface oxidized with chromic/sulfuric acid, then further functionalized by attachment of diamino-poly(ethylene glycol) (PEG) oligomers via carbodiimide coupling. An additional carbodiimide coupling reaction was used to link a peptide to the free amine functions of the PEG oligomers. Films were subjected to chemical, microscopic and spectrographic analyses after each step. Contact angle analysis showed the expected decrease in hydrophobicity (unmodified film, čwater=93.7°±1.6°) on oxidation (61.9°±1.2°) and a further decrease on PEG attachment (44.7°±1.1°). The acid-base nature of the surface groups was further characterized by contact angles derived for phosphate buffer at a range of pHs. Bromophenol blue dye demonstrated the presence of free amines on the PEG functionalized surface. Atomic force microscopy showed changes, or lack thereof, in film surface topography at each step of the process. X-Ray Photoemission Spectroscopy verified the nature of the chemical groups on the surface after each modification. This system has been developed to allow attachment of biologically active molecules to the surface of poly(ethylene). Active packaging with tethered bioactive compounds opens the doors to in-package enzyme processing of food products as well as novel antimicrobial packaging systems.
Session 45D, Food Packaging: General
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