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This project will continue under new funding and slightly modified objectives as PA-0021. The objective of this project is to generate analytical data for assessing the difference or equivalence of gamma and electron beam on packaging materials used for irradiated prepackaged foods.
The analytical data obtained also will be used to determine if there are any new compounds to be formed and what the concentrations these compounds, and the suitability of the test materials for irradiation at wide applicable doses. These results will help develop test protocol for assessing other packaging materials, and assist the Office of Premarket Approval in developing guidelines or a points-to-consider document for industry to follow. A soaker pad and two amorphous and nonoriented semi-rigid PET copolymers with cyclohexanedimethanol (CHDM) were studied. The initial results are as follows: Soaker Pad: The results obtained from the HS/GC/MSD analysis at 90oC showed that the 7-kGy gamma irradiation generated 2.3-3.14 ppm di-tert-butyl benzene, 0.78-1.40 ppm nonanal, and 0.24-0.41 ppm cyclopentanone. Irradiation significantly increased percent soluble solids extracted from the soaker pad specimens. After irradiation the soluble solid in the 10% aqueous ethanol solution was 0.43% compared to 0.28% before irradiation. The percent solid extracted from soaker pad specimens using 2-propanol increased with storage time, ranging from 0.71 to 0.94% in unirradiated and from 0.82 to 0.98% in irradiated. Glucose and cellobiose that could be generated from cellulose were present in the soluble solid extracted from unirradiated and irradiated soaker pad specimens with 10% ethanol solution at concentrations lower than 10 ppb based on soaker pad weight.
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The complete analysis of the soluble solid is underway. Amorphous and nonoriented semi-rigid PET: The PET materials have been irradiated with electron-beam accelerator at ambient temperature at 5, 25 and 50 kGy. The volatiles are being analyzed using HS/GC/FID and HS/GC/MSD. Nonvolatiles have been extracted using 10% ethanol and n-heptane food simulating solvents. Irradiation did not increase the percent soluble solid. Regardless of irradiation, soluble solid extracted from the PET using both food simulants is lower than 0.02% based on the PET weight. Analysis of the soluble solid by HPLC is underway.