Interaction between size, storage
Controlled atmosphere experiment.
Because there was a significant
interaction (P-value < 0.001) between
storage atmosphere and kiwifruit size
for changes in firmness during the
16-week storage period, firmness measurements
are presented for individual
treatments (storage/size). Kiwifruit
softening during the 16-week cold
storage period was related to fruit size
and storage atmosphere conditions
(fig. 1). The increase in SSC during
storage, however, was independent of
the fruit size and the storage atmosphere
conditions (data not shown).
Regression equations significantly described
firmness changes during storage
(weeks) for each of the storage
condition/size combinations (table 1).
Under both storage conditions,
large fruit had a slower rate of softening
than smaller kiwifruit. The rate of
fruit softening described by the slope
of the regression equations was always
slower under CA than air conditions
(table 1). Air-stored kiwifruit
softened approximately 2.6 times
faster than CA-stored fruit. After 16
weeks of CA storage, large, medium
and small kiwifruit had firmnesses of
12.0,9.0 and 9.0 lbf, respectively.
Large, medium and small air-stored
fruit all had firmnesses of approximately
3.0 lbf after this same period of
time (fig. 1).
Because kiwifruit are more susceptible
to vibration damage during packaging
and/or transportation when
they soften below 5.0 lbf, we ran our
regression equations to predict the
number of weeks to reach this firmness.
Under air-storage conditions,
large, medium and small kiwifruit
from this orchard reached 5.0 lbf by
12,lO and 8 weeks, respectively. In
contrast, large, medium and small kiwifruit
under CA storage conditions
were estimated to reach 5.0 lbf by 49,
30 and 20 weeks, respectively. Thus,the length of time the fruit could be
held safely in cold storage prior to
packaging was related to fruit size and
storage atmosphere.