Biomedical Engineering Reference
In-Depth Information
spp. in potatoes with gaseous
sec
-butylamine is 2 weeks.
88
Rind staining, which is
manifested as brown patches on the peel of oranges and lemons, possibly results
from mechanical abrasion occurring 12 to 24 h after packing.
89
The incidence of
rind staining can be reduced by preharvest sprays of dilute gibberelic acid.
90
R
ETARDATION OF
S
OFTENING
Softening associated with ripening make fruits susceptible to bruising and mechan-
ical injury. Fruits are often harvested when they are still in the mature green stage
to prevent mechanical damage. Apple softening can be retarded by 2,5-norborna-
diene (2,5-NBD), which acts by competing with ethylene for binding sites and
inhibits its action in plant tissues.
91
When applied to “Delicious” apples, as a gas in
either closed or flowing system, 2,5-NBD prevented the softening of apples stored
for 30 days at 25°C with either 2000 or 4000 µL 2,5-NBD/L of air. The firmness of
fruits was comparable for fruits held for 30 days at 5°C and loss of soluble solids
and starch was similar to that for the refrigerated apples.
D
AMAGE
D
ETECTION
For better quality control of fresh produce during storage and marketing, detection
of damage is important for it prevents if not minimizes the spread of diseases and
pests, and the downgrading of the product. Conventional damage detection is carried
out by visual inspection, which is time consuming and labor-intensive. For a long
time, researchers have tried to develop automated systems for detection of damage
and sorting. Among these are spectral analysis of acoustical signal which was tested
on apples,
92-95
carrots,
96
peaches,
36
radishes,
97
citrus,
98
and prunes;
99
delayed light
emission (DLE) on cucumbers;
57,100,101
automated color vision system that was tested
on fresh market peaches;
102
and nuclear magnetic resonance (NMR) which was tested
on “Bartlett” pears.
103
TEMPERATURE EFFECTS
The relationships between temperature, respiration, transpiration, and other deteri-
orative changes are well documented. Chilling and freezing injury occurs at low
temperatures and commonly occurs during cold storage, while high temperature
injury is likely to occur in tropical areas, or when the produce is exposed to the sun
after harvest.
I
NCIDENCE OF
C
HILLING AND
F
REEZING
I
NJURY
Chilling injury is a major problem in postharvest handling of susceptible plant
materials because it precludes the storage of many commodities at low temperatures.
As such, special transport and storage facilities are needed for effective handling of
fruits and vegetables in developing countries. For crops that are not traded in large
volumes, a major problem is encountered because there is a tendency to mix the
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