Retort pouches have traditionally been a multilayer flexible
packaging consisting mainly of polypropylene (PP), aluminum foil,
and polyester (PET). However, the aluminum foil barrier layer is not
suitable for microwave heating. Several non-foil barrier materials
are available to food processors desiring a microwaveable retort
pouch. Currently, polymer films with thin metal oxide coatings,
such as silicon oxide (SiOx) and aluminum oxide (AlxOy), are used in
retort pouch industries as non-foil barrier materials. The combination
of polymer materials with functional and protective coatings
offers a number of key advantages over alternative bulk materials.
SiOx or AlxOy coated films offer several advantages such as high gas
barrier, microwaveable, light weight, design freedom, and transparency