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

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
Physical Means 205
gloeosporioides (Spalding and Reeder, 1986b), and papayas infected by
various postharvest pathogens (Brodrick et al., 1976). Heat and
irradiation act synergistically to inactivate spore germination
(Barkai-Golan et al., 1969, 1977a; Sommer et al., 1967), shortening the
time of exposure needed for either treatment applied alone. The efficiency
of the combined treatment is influenced by the sequence and is generally
greater when heat precedes irradiation. The interval between heating
and irradiation also affects the synergism; for good results, radiation
should be applied within 24 h of the hot water treatment (Barkai-Golan
et al., 1969; Spalding and Reeder, 1986b).
A combination of heating and rinsing of fruits and vegetables has
recently been achieved by the development of a fast hot water spray
machine which simultaneously cleans the commodity and reduces the
pathogen population on its surface (Fallik et al., 1999; 2000); the device
is designed to be a part of a sorting line, and it exposes the commodity to
hot water (50-70°C) for 10-60 s. This method significantly reduced decay
incidence on sweet bell peppers and enabled fruit firmness to be
maintained during prolonged storage and marketing. The optimal
treatment conditions for this fruit were 55°C for about 12 s, while 59±1°C
for 15 s was optimal for Galia melons. The low percentage of decayed
fruits, together with the high level of cleanliness, were achieved by the
combination of the hot water rinse with brushing that removes dirt, dust
and fungal spores from the fruit, calyx and skin. The improved keeping
quality of the rinsed and disinfected fruit has also been attributed to the
melting of the wax layer, which seals small, almost invisible, cracks in
the epidermis (Fallik et al., 1999; 2000).
B. IONIZING RADIATION
The possibility of utilizing ionizing radiation for extending the shelf
life of fresh fruits and vegetables has been studied since the 1950s. These
studies were mainly aimed at three directions: (a) control of postharvest
diseases; (b) delay of the ripening and senescence processes; and
(c) control of insect infestation for quarantine purposes. Most of the
studies were carried out with CO^^ gamma rays. Here, we will focus on
irradiation as a physical means for decay control and postharvest life
extension of fruits and vegetables. This subject has been separately
reviewed (Barkai-Golan, 1992).
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