Optimization of the shelf life of lamb forelegs packed in different multilayer polymeric materials and modified atmospheres.

Lamb forelegs were packed in three different gas mixtures (Treatment N2: 70% N2-30% CO2; Treatment O2: 70% O2-30% CO2; Treatment Ar: 70% Ar-30% CO2) and two types of polymeric materials (B1, a polyamide-polypropylene bag and B2, a bag made of bio-oriented polyamide, aluminium and polyethylene). Physical, chemical and microbiological parameters were determined, initially and after 7, 14 and 21 days of storage (3 ± 1 °C). Colour and oxidative stability decreased and the number of microorganisms increased significantly during the storage period. Treatment O2 increased a* and TBARs. Despite the different permeability to O2, shown by the polymeric material (< 6.0 vs . < 0.5 cm3/m2/24 h bar), the different types of packaging did not significantly affect any of the studied parameters. Regarding the atmosphere treatment or type of packaging, these factors did not significantly affect mesophile or Enterobacteriaceae counts either.