Compensation of Pinhole Defects in Food Packages by Application of Iron-based Oxygen Scavenging Multilayer Films

摘要

To protect sensitive food products from oxidative deterioration, multilayer barrier film systems and also modified atmosphere packaging are widely applied. However, the preservation of food quality in such packaging systems may be compromised by the presence of defects in the sealing layer of the films, especially when these are below a critical size, typically the detection limit of standard leak testers of 10 μm. The addition of an oxygen scavenger (OS) layer in barrier film structures could therefore provide extended protection against O_2 penetration through such defects. In this study, O_2 absorption of different multilayer film structures including an iron-based OS were investigated under defined gas atmospheres. Measurement cells were thereby covered with plastic films of defined O_2 permeability to simulate conditions in a food package during storage with pinhole defect sizes of 10 and 17 μm. The results indicated that the OS film structures applied could only compensate for a defect size of 10 μm in the sealing layer. Analysis of the O_2 absorption of different multilayer film structures at 85% and 100% relative humidity showed that higher humidity accelerates the activation of the scavenger. After full activation, the scavenger kinetics are the same for 85% and 100% relative humidity. Long-term storage experiments using the most effective film structure from the preliminary experiments were carried out to compare O_2 absorption of a snack food product in packages with and without an OS. The analyzed linear gradient of the reaction of the OS film and food product, respectively, indicated first-order reaction kinetics with corresponding reaction constants calculated to be K (food product) 0.021 mg (O_2) mbar (O_2)~(-1) day~(-1) and K (OS film) 0.066 mg (O_2) mbar (O_2)~(-1) day~(-1). The reaction velocity of the OS was thus three times faster than that of the food. The applicability of OS multilayer film systems to compensate a critical pinhole defect size of 10μm for sensitive food products could therefore be confirmed. The measurement of quality parameters for the status of lipid oxidation processes would help to verify this result.