Post harvest diseases fruits and vegetables - Xavier University ...

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
134 Postharvest Diseases of Fruits and Vegetables
The retardation of yellowing and decay in CA storage has been
reported for various leafy vegetables, for which CO2 and O2
concentrations are controlled during storage (Lipton, 1987). MAP has
proved effective for extending the postharvest lives of green herbs,
including dill, parsley, coriander, chives, chervil, watercress and sorrel.
Such an atmosphere was achieved by packaging fresh herbs in
non-perforated polyethylene-lined cartons (Aharoni et al., 1989).
Retardation of senescence processes in these yellowing-susceptible herbs
was again attributed to the high CO2 levels accumulated within the
package and the ethylene-antagonistic action. However, only little
commercial success was reported for the use of this procedure with green
herbs, because of the difficulty in controlling the O2 and CO2 variations
within the package. The drastic decrease in the O2 level, combined with
the increased CO2 level, may lead to anaerobic respiration, fermentation
and development of an off-flavor (Cantwell and Reid, 1993).
In order to obtain beneficial fungistatic concentrations of CO2 within
polymeric packages of sweet corn, retail packages were stored at 2°C
within additional plastic liners (Rodov et al., 2000). The MA generated in
these packages by the corn respiration complied with the recommended
range of 5-10 kPa CO2, and inhibited mold development. However, when
the produce is transferred to shelf life, the outer layer should be opened
to counterbalance the enhancement of the corn respiration at the higher
temperature and to prevent O2 depletion and off-flavor development.
Further advances in modified atmosphere packaging involve the
development of 'active' or *smart' films which, in addition to their ability
to generate the conventional modified atmosphere around the
commodity, are also capable of actively improving the atmosphere
(Church, 1994). These properties have been imparted by introducing into
the package, or into the packaging materials, compounds capable of
altering the atmosphere composition by absorbing atmospheric gases,
vapors, wetness and by-products. Ethylene, which is produced by fruits
and vegetables during storage, may accumulate in the package and
stimulate their ripening and senescence processes that may lead to
shortening their postharvest life. By the use of ethylene-scavenging
materials, the smart packaging is capable of retarding these processes, so
providing a significant shelf-life extension. As a matter of fact, packaging
broccoli in such a film doubled the shelf life of the fresh produce (Church,
1994). The shelf life of banana fruits sealed in bags made of polyethylene
treated with the anti-ethylene compound, 1-methylcylclopropane, was
extended from 16 days in non-treated polyethylene bags up to 58 days in
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