Mechanical and Temperature Effects on Shelf Life Stability of Fruits and Vegetables - Food Shelf Life Stability: Chemical, Biochemical, and Microbiological Changes - page 59

commodities in one refrigerated vehicle or storage. Chilling injury occurs during
the cold treatment of citrus (exposure at low temperature for a prescribed period),
e.g., grapefruit, but is one of the approved quarantine procedures for the control of
Mediterranean fruit fly. 104 There are 10 visual symptoms associated with chilling
injury, namely:
1.surface lesions — pitting, large sunken areas, and discoloration
2.water-soaking of tissues — disruption of cell structure and the accompa-
nying release of substrates favoring growth of pathogens
3.internal discoloration or browning of pulp, vascular strands, and seeds
4.breakdown of tissues
5.failure of fruits to ripen following removal from storage
6.accelerated rate of senescence
7.increased susceptibility to decay
8.shortened shelf life due to one or more of the above responses
9.compositional changes related to flavor and taste
10.loss of growth capacity for stored propagules. 105
The lowest safe storage temperature from chilling injury and the corresponding
symptoms for fruits and vegetables are shown in Table 2.7 . Surface pitting, necrotic
areas, and external discoloration are apparent symptoms of chilling injury. Cucum-
bers show surface pitting when stored at 10°C or below. 132 Similarly, chilling injury
in green beans appears as streaky soft spots and slimy patches. 133 At mild chilling,
green bananas develop smoky or dull-yellow appearance 134 and on more severe
chilling, the peel turns dark brown or black. In peaches, symptoms of chilling injury
include lack of juiciness (mealiness, wooliness, leatheriness), browning of the flesh,
increased susceptibility to decay, and loss of ability to ripen. 135 Luza and co-
workers 135 reported that 10°C was a much better temperature for short-term storage
of peaches than 5°C, although the fruits could be stored longer without development
of noticeable symptoms. However, symptoms of chilling injury developed rapidly
upon transfer of the fruits previously kept at 5 to 20°C for ripening. Sea transport
is ideal for mangos because of its low cost, but it seems the fruits do not respond
well to low-temperature storage during the long journeys. Storage of mangos at 8°C
can cause chilling injury as evidenced by their failure to ripen. 136 Avocados also
failed to ripen normally and develop a distinct climacteric rise signaling the onset
of ripening when stored at temperatures of 4 to 5°C. 137 For mature-green guavas,
chilling injury occurs at storage temperature of 3.5 to 7°C. 138 Superficial scald, a
brown discoloration giving the skin a cooked appearance in some apple cultivars,
is also a chilling injury symptom evident after long-term storage at 0 to 4°C. 139,140
Freezing injury is a separate phenomenon from chilling injury because it results
from the freezing of tissues and formation of ice crystals at temperatures below the
freezing point. 2 This is common among some vegetables because they are stored at
or near freezing temperatures. Freezing injury in broccoli florets yields strong off-
odors during cooking and globe artichoke, asparagus, lettuce, celery, and sweet corn
have been classified as highly susceptible to freezing injury. 7