Effect of Plastic Film Types on Kinetics of Ethanol Vapours Release and Application in Active Packaging

Abstract

Active packaging incorporating with ethanol vapour release system has been of interests for developments to delay quality changes of fruit and vegetables. The present work was undertaken to study effects of plastic films including PLA, BOPP and LDPE which were main components of so-called ethanol vapour controlled release sachet, on kinetics of ethanol vapour release in the packages. Experimental results indicated that FPE investigated using isostatic and gravimetric methods were exponentially dependent on concentrations in a range of 0.36-3.17 mol/m³. The relationship was well predicted by the mathematical model having RMSE = 0.0003. Considered at or near concentrations, FPE values were in a decent order of LDPE > BOPP > PLA. Rates of ethanol vapour released into- and concentration levels of ethanol vapour in headspaces of packages were consistent to values of FPE of individual films. In this study, the ethanol vapour controlled release sachet was incorporated into the active packages containing fresh-cut ripen papaya. This was conducted in comparisons to the package having no sachets (designated as control). Experimental results showed that the packages having sachets, except those having PLA sachets, could provide visual microbial growths better than the controls. The sachet made of BOPP film could release ethanol vapour into the package causing higher ethanol vapour concentration accumulated compared to the sachet made of LDPE. This made the BOPP sachet better controlling visual microbial growth. However ethanol concentrations accumulated in papaya in the package having LDPE sachet were higher than those in the package having BOPP sachet. Overall, the BOPP film had potentials for making so-called slow release sachet that could release the ethanol vapour at effective levels for delaying microbial growth.    

Keywords: Polylactic acid (PLA), Biaxially oriented polypropylene (BOPP), Low density polyethylene (LDPE), film permeability to ethanol vapour (FPE), kinetic of ethanol vapour release