These are products such as frankfurters, sausages, luncheon meat, bacon, dried beef, processed turkey and chicken parts. Unlike fresh meat, they are always packaged by the food processor and therefor need additional protection against oxygen uptake and moisture loss to provide the long shelf life they require for lengthy distribution chains and irregular purchasing patterns by consumers.
Unlike fresh meat, the red color of processed beef products is maintained by adding special ingredients in the processing, e.g. salt, spices, and sodium nitrite. Multilayer films incorporate good oxygen barrier films such as PVDC, EVOH, or 6 nylon are the usual choices to satisfy the long shelf life requirement.
In the more recent past, the higher cost of specialty ethylene copolymers has impelled packagers to utilize blends of acid copolymers or ionomers using a lower cost EVA.
A large number of these products get packaged in thermoform-fill-seal equipment, which requires sound draw characteristics for the forming web. It is notable that 6 nylon meets this requirement owing to its excellent toughness, whereas the requirement of oxygen barrier renders processed meat applications the biggest food packaging market as far as the 6-nylon film is concerned in the USA.
In scenarios where nylon’s oxygen barrier is inadequate, a layer of EVOH or gets added with PET or Nylon being the primary lidding component. Both top and bottom webs are heat sealed using LDPE, EVA, or ionomer/ acid copolymer.
HIPS or PVC provide stiffness in thermoform-till-seal packages for luncheon meats with PVDC providing the oxygen barrier and in a PVC/PVDC co-extrusion provides the lid.
Usually, hams are packaged in the shrink bags via the aforementioned systems. Composite nylon/EVOH/ionomer films are used for hams that are meant to be cooked in the package.
PVDCs, which impart a robust oxygen barrier or LLDPE in scenarios where a weaker barrier will suffice, typically belong to the processed meat varieties which are capable of being extruded. These include sandwich spread, sausage, and liverwurst, which are packaged in form-fill-seal equipment placed within cylinders that are tightly filled chubs – closed with a twist of wire at both ends.