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

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
132 Postharvest Diseases of Fruits and Vegetables
senescence processes of the fruit and maintaining host resistance. Decay
during prolonged storage can be almost prevented by application of
fungicidal sprays during the flowering season preceding polymeric film
packaging (Aharoni and Barkai-Golan, 1987).
A reduction in the incidence of brown rot caused by Monilinia
fructicola was recorded in sweet cherries packaged in polyethylene bags
and stored at 0.5°C for 42 days. Disease reduction under these conditions
was attributed to the modified atmosphere of 5.1% O2 and 11.4% CO2
produced within the package during storage (Spotts et al., 1998). A
further reduction in disease incidence was achieved when a preharvest
fungicide treatment had been applied prior to packaging, or when the
fruit was treated with a postharvest antagonistic yeast (see the chapter
on Biological Control). The disease-suppression effect of CO2 in sweet
cherries was regarded as fungistatic, since decay developed normally
when the fruit was returned to air (De Vries-Paterson et al., 1991). In a
study with d'Anjou pear fruits, the combination of MAP (2-6% O2 and
0.5-1% CO2) with an antagonistic yeast as a biological control agent was
found to reduce the blue mold {Penicillium expansum) better than the
modified atmosphere without the yeast or the yeast application followed
by storage in air (Miller and Sigar, 1997).
MAP has been found to improve the storability of perishable
commodities such as fresh herbs, broccoli and green onions. Packaging
broccoli heads in sealed polyethylene bags inhibited both senescence and
decay development in the flower buds, and kept the produce green and
fresh during prolonged cold storage (0.5°C) followed by 2 days of shelf-life
conditions (20°C) (Aharoni et al., 1986). The extension of the useful life of
broccoli was attributed to the high respiration rate of this vegetable,
which resulted in CO2 accumulation from 2-3% in cold storage to 6-8%
after transfer to shelf-life conditions (20°C); O2 concentrations decreased
to about 6% at shelf life. Decay suppression under these conditions was
attributed to the delay in host senescence by the CO2, because of the
ability of the gas to curb the action of the endogenic ethylene, which plays
a primary role in the control of aging of broccoli. The improvement of
storability of broccoli heads in sealed PVC film is illustrated in Photo 1.
Green onions were found to resist a relatively high concentration of
CO2 (more than 15% for a short period) produced in sealed
microperforated film (Aharoni et al., 1996b). The elevated level of CO2,
combined with the decreased level of O2 inside the packaging reduced
growth, yellowing and decay of the green leaves (Photo 2).
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