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

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
128 Postharvest Diseases of Fruits and Vegetables
Evaluation of CA Efficiency
Apples are an example of fruits for which CA is aimed primarily at
retardation of ripening (Blanpied, 1990). Low O2 and high CO2, in
combination with a low temperature, delay the climacteric of the fruit
more than low temperature alone. Striking benefits were obtained with
such combinations, especially in apple cultivars that suffer from chilling
injury at temperatures near 0°C, and those which have a short storage
life (Salunkhe and Desai, 1982; Sommer, 1985). A considerable
improvement in the storage quality of several apple cultivars occurs
following a reduction of the O2 concentration in the atmosphere to
1-1.5%, immediately after harvest (Couey and Williams, 1982). Later
findings showed the advantage of CA in which O2 at less than 1% was
combined with ethylene removal. Under these conditions apple fruits
remained firmer and their resistance to pathogens, such as Penicillium
expansum and Monilinia fructicola, was increased (Stow and Geng,
1990). Studying the effect of decreased O2 concentrations combined with
ethylene removal on Cox's Orange Pippin apples, Johnson et al. (1993)
found that fruits stored in 0.75% O2 were firmer and showed lower
incidence of Penicillium and Monilinia rots than those stored in 1.0 or
1.25% O2. This was achieved through the reductions both in primary
infection and in secondary infection by contact between infected and
sound fruit. The development of Botrytis and Nectria rots, however, was
unaffected by the lower oxygen concentrations.
Low O2 storage (1%) also considerably reduced Botrytis development in
Kiwifruits at 0°C, along with the delay of the fruit softening and ethylene
production, which are ts^ical with infected fruit (Niklis et al., 1992).
Sitton and Patterson (1992) found that CA storage of several apple
cultivars with CO2 concentrations above 2.8% was more effective than
I0W-O2 oxygen atmospheres, in reducing decay development incited by
Botrytis cinerea and P. expansum. However, the response to CO2
treatment depended on the physiological age of the fruit. Apples that
had been stored in air at 0°C for 8 months, prior to the CO2 treatment
showed increased skin discoloration, whereas younger apples, even
under higher CO2 did not show skin darkening. It was suggested that
high-C02 CAs could be beneficially used to control postharvest disease in
freshly harvested apples (Sitton and Patterson, 1992). High CO2 (25%)
was also found beneficial for cherry fruits by totally preventing decay
development during both refrigeration and shelf life (Brash et al., 1992).
Avocados benefit greatly from CA storage. Early studies had already
shown that the climacteric respiration peak of avocado fruits was delayed
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