PAPER PRESENTED AT IAPRI SYMPOSIUM 2013 Porous Ultrahigh Gas-Permeable Polypropylene Film and Application in Controlling In-pack Atmosphere for Asparagus

摘要

Porous polypropylene (PP) films with greater gas permeability and lower permeability ratios (β) than existing commercial films were developed for fresh produce packaging. PP containing high content of beta-form crystal was biaxially stretched under controlled conditions. Resulting porous films with uniquely high oxygen transmission rate (OTR) of 2659000 cm~3·m~(-2)·d~(-1), water vapor transmission rate of 67 g·m~(-2)·d~(-1), and β value of 0.76 was used as a "breathable window" attached to the less permeable commercial BOPP (biaxially oriented PP) lidding film. Various sizes/areas of the breathable windows were designed and tested on packaging asparagus of 400 g, at 5℃. Results demonstrated that in-pack O_2 and CO_2 concentrations could be practically controlled and modified by changing areas of the breathable windows. Altered porous high OTR area directly affected total gas permeation of the package. Optimum gas composition of O_2 and CO_2 within the recommended controlled atmosphere for asparagus, stored at 5℃, was effectively created and maintained in the package containing 25 cm~2 breathable window (15% of total film lid's area). The shelf life of asparagus under optimum modified atmosphere was extended to 29 days, as compared with <3 days in the normal, low OTR tray sealed with BOPP lidding film. Clearly, these developed porous ultrahigh permeable PP films can be useful materials in designing high OTR package with desirable in-pack O_2 and CO_2 concentrations.