The nested packages comprising regular PVCwrapped
retail trays with a removable external
V. Rodo6 et al. / Posthar6est Biology and Technology 18 (2000) 259–266 263
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
Fig. 2. Effect of packaging material on partial pressures of O2
and CO2 inside retail packages of sweet corn during cold
storage at 2°C and the shelf-life period at 20°C. Each retail
package contained a cardboard tray with a pair of trimmed
corn cobs. Plastic films used for retail packaging: Xtend-microperforated
Xtend film; PVC-polyvinylchloride wrap;
SM60M-perforated polyolefin SM60M. The retail packages
were stored either within the liners of microperforated Xtend
film, or in open cartons without liners. During the shelf-life
period, the liners were opened.
Fig. 1. Effect of nested packaging on partial pressures of O2
and CO2 and concentration of ethanol vapor inside retail
packages of sweet corn during cold storage at 2°C and shelflife
at 20°C. The PVC-wrapped retail packages were stored
either in open cartons without liners, or in cartons with liners
of microperforated Xtend film (nested package). During the
shelf-life period, the liners were either left closed, or opened
and subsequently folded, or opened and rolled down the
carton. Bars indicate standard deviations of three atmosphere
samples taken from different nested packages.
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
264 V. Rodo6 et al. / Posthar6est Biology and Technology 18 (2000) 259–266
about 5 kPa CO2 during cold storage, but CO2
declined sharply after opening the liner during the
shelf life period.