100B-14 |
Comparison of water vapor transmission in model systems and food packages for commercial food wraps |
M. D. STEVEN and J. H. Hotchkiss. Dept. of Food Science, Cornell Univ., 160 Stocking Hall, Ithaca, NY 14853 Permeation into a package is the sum of permeation through the material and permeation through the seals. Although addressed for hermetically sealed and modified atmosphere packages, there has been little consideration of total package permeation and the contribution of seals for commercial food wraps. Our objective was to compare total package and material water vapor transmission rates for commercial food wraps under both ambient and refrigerated storage conditions and to determine the applicability of a model system for predicting the performance of real food products. Standard protocols were used to calculate package and material water vapor transmission rates (WVTRs) for seven commercial food wraps: aluminum foil, poly(vinylidene chloride) (PVdC) film, 2 poly(ethylene) (PE) films, an adhesive-modified PE film and plasticized poly(vinyl chloride) (PVC) film. Water ingress into complete packages was compared to the calculated material permeability for the package, with the difference attributed to seal permeation. Film adhesion strengths were measured; a model system (desiccant) was compared to food products. The adhesive-modified PE film had the smallest difference (0.7E-03 g/h) between material and package transmission rates (seal permeation), approximately half that of PVdC film (1.1E-03 g/h). Differences for the remaining films ranged from 2.3E-03 to 3.9E-03 g/h. WVTRs for the materials as flat films compared favorably to literature values. There was a significant difference in the relative package permeabilities of the wraps at ambient and refrigerated temperatures, which is attributed to reduced adhesion of most wraps under refrigeration. At ambient temperatures, the adhesive-modified PE film had the greatest adhesion strength, followed by the PVC film. Test results for the model system paralleled those of food products. The model system successfully predicted the moisture loss/gain of real food products, suggesting that future tests can be conducted with desiccant and the results readily extrapolated to food systems. The storage trials show the relative importance of material and seal permeation for commercial food wraps, providing guidance for the design of novel products.
Session 100B, Food Packaging
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