The use of microperforated Xtend liners during
cold storage of sweet corn did not cause hypoxic
fermentation, provided the liner was opened at
the onset of the shelf life period. Moreover, the
cobs cold-stored within the nested packages,
tended to produce less ethanol (Fig. 3) and sometimes
less CO2 (Fig. 2) during the shelf life period
than those cold-stored in the same kind of retail
packages without the liner. One of the possible
explanations of this phenomenon may be the
higher infection level of cobs stored without external
liners, and the contribution of molds and
yeast on the cob surface into overall respiration:
fermentation rate of the retail package. On the
other hand, physiological differences between
cobs cold-stored at different conditions may have
existed and contributed to observed differences in
gas exchange and fermentation.
Packaging in perforated SM60M film caused
severe microbial spoilage of sweet corn, probably
due to the absence of fungistatic modified atmosphere
combined with abundant accumulation of
condensed water. These observations are in agreement
with the mathematical model of MA packaging
predicting that film perforations have much more
pronounced effects on O2 concentration, than on
relative humidity inside the package. In fact, the
highly perforated SM60M film had the lowest
barrier properties for gases but the highest barrier
properties for water vapor among the three packaging
materials tested. In contrast to the poor
performance of perforated polyolefin with sweet
corn, the same film markedly improved storage
life of bell pepper due to providing optimal humidity
inside packages (Rodov et al., 1998). This
difference probably results from different requirements
of the two vegetables to storage conditions
and MA composition, as well as from the much
higher transpiration rate of sweet corn, which is
20 times more than that of bell pepper