Refrigerated processed meats are high added-value products traditionally vacuum-packed in plastic packages to minimize contact of the product with oxygen and, consequently, prolong their shelf life. This study aimed at elaborating a comprehensive and detailed overview of the packaging materials used on the Brazilian market to manufacture thermoformed packages for sausages, hot dogs and sliced processed meat, in addition to cook in-type packages for hams and restructured ham products. Basically, the materials most used are coextruded films or a combination of coextruded and laminated (top film) structures. Polyamides, EVOH and PET-PVDC are used to provide an oxygen barrier. The oxygen transmission rate (O2TR) of bottom films for thermoformed packages varied between 5 and 30 cm³ (STP)/m²/day, with lower values for the films used in the package of sliced processed meat. The O2TR of top films were of the order of 10 cm³(STP)/m²/day, determined at 23 °C under wet conditions. Perforation resistance was about 25N (top films) and 35N (bottom films-sausages/hot dogs). The bottom films for sliced processed meat varied considerably in terms of puncture resistance due to the wide range of thickness available. A series of packages currently in use on the Brazilian market were evaluated for seal integrity and thickness distribution of the thermoformed film. No sealing problems were detected. The reduction of total film thickness at the corner of flexible trays (critical area) for sausages and hot dogs, whose depth is larger than for sliced processed meat packages, varied between 42 and 65%. The reduced thickness at the corners significantly affects the gas barrier properties of the package and justifies the use of EVOH which does not cause the shelf life to decrease.
Flexible plastic packaging; oxygen permeability; mechanical properties; puncture resistance; meat package
