The nested packages comprising regular PVCwrapped
retail trays with a removable external
Xtend liner, maintained the CO2 partial pressure
within the recommended range of 5–10 kPa both
during the cold storage and the shelf life, provided
the liner was opened after transfer to 20°C. Without
the external liner, the steady-state CO2 level
inside cold-stored PVC-wrapped trays did not
exceed 3 kPa. If the liners were left closed or just
folded during the shelf life, the in-package O2
levels inside the retail packages decreased to 4 or
8 kPa, and CO2 concentrations increased to 27 or
17 kPa, respectively (Fig. 1). These changes in
atmosphere composition were accompanied by an
increase in ethanol accumulation (Fig. 1), indicating
active fermentation.
When Xtend film was used for retail packaging
instead of PVC wrap, the CO2 level was kept
within the limit of 10 kPa during the cold storage
(Fig. 2). However, after transfer to 20°C the atmosphere
composition in these Xtend retail packages
demonstrated clear signs of fermentation,
similar to those observed within external Xtend
liners closed during the shelf life period. On the
contrary, substitution of PVC wrap by perforated
SM60M polyolefin did not create a modified atmosphere
if not combined with an external liner.
Combining these highly perforated retail packages
with the Xtend liner allowed accumulation of
about 5 kPa CO2 during cold storage, but CO2
declined sharply after opening the liner during the
shelf life period.