Shrink Packaging: Plastic shrink films are used for wrapping large and uneven cuts of fresh meat. It is a technique in which heat shrinkable polymer film is shrunk around the meat product by application of heat to achieve a skin-tight and compact pack. The packaging film should have structural strength. It should be a good water vapour barrier and be capable of withstanding storage temperature of about – 45 °C. The advantages of plastic shrink film include neat appearance, ease in handling and a contour fit. Hot tunnels are used to effect a tight wrap. Heat shrinkable poly(vinyl chloride) (PVC), polypropylene (PP), irradiated polyethylene (PE) and poly(vinylidene chloride) (PVdC) are used to shrink wrap fresh meat.
Skin Packaging: Another development that offers advantages for presentation as well as packaging design variety is skin packaging. The process allows the packaging film to conform exactly to the profile
of the product. This gives rise to many opportunities for enhanced product presentation as well as further improving the integrity of the pack itself. In a skin pack, the product becomes the die for the thermoform packaging operation. The semi-rigid bottom web may or may not be thermoformed. The top web is heated in an evacuating chamber until it is near its melting point, at which it drapes over the product and forms a skin around all the contours. Upon sealing and cooking, it retains its new shape, ensuring intimate contact with the product, irrespective of surface irregularities. Skin packs are prepared with an oxygen barrier plastic film.
There are four categories of preservative packaging that can be used with raw muscle foods (Table 2). These are vacuum packs (VP), high oxygen modified atmosphere packs (high O2 MAP), low oxygen modified atmosphere packs (low O2 MAP), and controlled atmosphere packs (CAP).