Gas Transmission Rates of Commercially Available Polyethylene and Polypropylene Films for Modified Atmosphere Packaging

摘要

Oxygen transmission rates (OTR) of low-density polyethylene (PE) and polypropylene (PP) films were measured at 10,15 and 17 deg C using the whole-bag method of Wloyls (2004) for unperforated films. PE films with a nominal thickness of 30,40,60 and 80um (PE30, PE40, PE60 and PE80, respectively) were analyzed; thickness of the PP film was 40 um. Oxygen and CO_2 transmission rates (CO2TR) of 35-mu m micro-perforated polypropylene (MPP) were measured at 10, 15, and 17 deg C using the method describedby Ozdemir et al. (Ozdemir I, Monnet F, Gouble B. 2005. Postharvest Biol Tech 36:209-213). Temperature effects on unperforated PE and PP films followed Arrhenius kinetics (R~2 > 0.970). Activation energy (E_a) of PE film had a range of 28.1-35,0 kJ mol~(-1); for PP film, E_a was 38.1 kJ mol~(-1). In general, E_a of PE film increased as film thickness (t_F) increased. Q_(10-Tr) values at 10-20 deg C for PE and PP were 1.50-1.66 and 1.74, respectively. Temperature had no definite effect on OTR and CO2TRof MPP. Mean OTR and CO2TR for MPP were 10,848 and 9,554 mL m~(-2) d(-1), respectively. The average perforation diameter (D_(mp)) and density (d_(mp)) was 41.0 um and 125 perforations per m~2, respectively, for a 20 cm x 28 cm bag. Comparisons with published data showed the sample film to have gas transmission rates at the lower end of the range for such types of packaging film.