Polymeric packaging films for thermal pasteurization processes

Pasteurized ready-to-eat meals require a refrigerated storage and/or in combination with aerobic environment as anaerobic spores are not inactivated during pasteurization processes. Use of low-barrier polymeric packaging can create an aerobic environment inside the package, however, it causes oxidation in food. Barrier properties of polymeric packaging are affected by thermal pasteurization and causes further degradation of food quality. Microbial safety and quality degradation of packaged foods are also dependent on amount of oxygen present at the package headspace and in food matrices. Therefore, storage temperature, barrier properties of polymeric packaging, oxygen at package headspace and oxygen diffusion in food together determine the shelf life of a pre-packaged pasteurized ready-to-eat food.;In the first study, the effect of oxygen transmission rate (OTR) of polymeric packaging films on oxidation-reduction potential and quality attributes in ready-to-eat pasteurized blue mussels in red sauce and shredded carrots were evaluated during refrigerated storage. Results showed that the oxidative degradation of nutrients in mussels and shredded carrots were higher in the package of high OTR films. The degree of influence was dependent on chemistry of food. It also suggested to store the pasteurized food at refrigerated temperature.;In the second study, changes in gas barrier properties of multilayer polymeric packaging films were evaluated after hot water and microwave-assisted pasteurization (MAPS) processes. Both processes affected the gas barrier properties of films. The degree of deterioration in gas barrier properties depended on hydro-philic/phobic nature of polymers, temperature, and duration of pasteurization processes. Films were suitable for both hot water and MAPS processes.;In the third and last study, a non-invasive methodology was developed to investigate oxygen diffusion in model food gels at temperatures ranging from 4--22°C using oxydot luminescence sensor. It demonstrates that Oxydots can be used at multiple locations with in a food to determine the oxygen content. Oxygen diffusivity significantly decreased with increasing solid concentration and further lowered with decreasing temperature.;The findings from the present study will be useful to select a suitable packaging films for pasteurization processes. It will also help to measure oxygen diffusion in food to describe microbial growth and oxidation processes.