Linking morphology changes to barrier properties of polymeric packaging for microwave-assisted thermal sterilized food

It is a priority to develop polymeric packaging that can withstand microwave-assisted thermal sterilization (MATS) and maintain the quality of low-acid foods during long-term storage. In this study, we explored changes in the morphology of pouch films with two multi-layer structures. The films are based on barrier layers of metal oxide-coated poly(ethylene terephthalate) (PET) (film A) and ethylene vinyl alcohol (EVOH) (film B). A 8-oz model food in pouches was processed with MATS (F-0=9.0 min) and stored at 23, 35 and 45 degrees C for up to 12 months. Findings reveal that the oxygen barrier of film A was influenced by the coating and crystallinity of PET. The oxygen barrier of film B was primarily affected by the moisture content of the EVOH polymer. Results also show that changes in barrier properties depended on storage temperature. Recrystallization in polymer might be an important morphological change that occurs during storages. (c) 2017 Wiley Periodicals, Inc.