45D-23 |
The effects of electron beam irradiation on ethylene vinyl alcohol copolymers |
V. KOMOLPRASERT1, T. P. McNeal2, and T. H. Begley2. (1) National Center for Food Safety & Technology, U.S. Food & Drug Administration, Division of Food Processing & Packaging, 6502 S. Archer Rd., Summit-Argo, IL 60501, (2) Center for Food Safety & Applied Nutrition, U.S. Food & Drug Administration, Office of Food Addative Safety, 5100 Paint Branch Pkwy., HFS-245, College Park, MD 20740-3835 Justification: Ethylene vinyl alcohol (EVOH) is used to improve barrier properties of food packages. FDA does not permit it for pre-packaging of irradiated food; hence this study will help evaluate its chemical stability upon irradiation. Objective: Determine the chemical changes in EVOH copolymers after exposure to electron beam irradiation. Methods: EVOH copolymer resins without and with a-methyl styrene dimer were cryogenically ground, and exposed to electron beam irradiation at 5, 25 and 50 kGy doses at room temperature. After irradiation, volatiles in the resins were analyzed using HS/GC/MSD. Non-volatiles were extracted using 10% and 50% ethanol solution at 40oC for up to 10 days, and the extractable solids were measured. Results: EVOH without a-methyl styrene dimer generated many more volatiles than EVOH with the additive. The amounts of volatile chemicals in both copolymers increased as the irradiation dose increased. Qualitatively, e-beam radiation of EVOH without the additive produced aliphatic hydrocarbons and almost every oxidation product. In EVOH with the additive, very few polymer breakdown products were detected. Major volatiles were breakdown products of the a-methyl styrene dimer including alkyl aromatics such as t-butyl benzene and isobutyl benzene, and oxygenated aromatics such as acetophenone and 2-phenyl isopropanol. The average percent extractable solids from non-irradiated EVOH with a-methyl styrene dimer into 10% and 50% ethanol solution were 0.7 % and 2.5%, respectively. Irradiation at 5-50 kGy doses did not increase those levels. However, irradiation increased the soluble solids extracted from the EVOH specimens without the additive. Before irradiation, the average percent extractable solids were 0.27% and 1.24% for 10% and 50% ethanol solution, respectively. After 50 kGy irradiation, the levels increased up to 0.45% and 1.94%, respectively. Significance: EVOH containing a-methyl styrene dimer is chemically more stable than EVOH without the additive after exposure to e-beam irradiation up to 50 kGy.
Session 45D, Food Packaging: General
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