in different varieties. There is a different safe temperature range
for tropical and temperate fruits. Tropical fruits like pineapples,
bananas, pawpaws, etc., may be injured at temperatures below
15"C, whereas apples, peaches, plums, etc., may be stored at
temperatures lower than 5-6 C.

Post-Harvest Losses Due to Improper Handling
During Transport and Storage
 It is generally believed that fresh produce can't be handled or
harvested without inflicting injuries, but with careful ground-
work and precaution, the damage can be appreciably minimised.
Frequently, the injuries appear in the form of abrasions, cuts or
bruises. When the commodities are injured there is a marked rise
in the evolution of carbon dioxide or uptake of oxygen. The cells
very close to the injury point which are not killed in the process,
respire much faster. This increase in the rate of respiration is said
to be responsible for production of certain compounds which of-
fer resistance against microbial attack.
 The evolution of the ethylene gas from the wounded part
could trigger ripening among the injured fruits and/or nearby
sound fruits stored in the same box, room or hold.
 During harvest, produce may get abrasion or cut injuries.
Abrasion injuries result from friction between two fruits, fruit
and the walls of a box, conveyor belt, etc. Cuts may result from
contact with a sharp object or from fingernails of harvesters/
handlers. Produce like ground provisions, which most of the time
are cut from the parent plant, are left with open wounds. They
are the most vulnerable spots for the hibernation of post-harvest
pathogens resulting in various type of rots, etc. Injuries should,
therefore, be kept minimum both in number and severity.
 Bruises usually occur by impact or by compression. This results
in the death of the outer cells which ultimately develop into
brown patches, making the commodity very unattractive in ap-
pearance. While making a quality assessment, factors like ap-
pearance, size, shape, skin texture and blemishes are collectively
taken into account.

Post-Harvest Losses Due to Pre- and Post-Harvest Diseases
 Virtually every fruit and vegetable is susceptible to at least one
of the post-harvest diseases initiated at a cut stem.
 The important casual organisms responsible for deterioration
of quality are fungi, bacteria and viruses. In the case of
vegetables, bacteria are mostly responsible for serious nutritional
and quality losses. The deterioration can be checked by proper
chemical treatment, etc. However, chemical treatment will only
help if the pathogen has not penetrated deep into the host tissue.
The moment rotting takes place, the level of ethylene generation
increases, which causes healthy fruit to ripen prematurely and
may transfer pathogens to them. Deep seated, latent pre-harvest
infections initiated during the development of fruits in the plan-
tation are hard to eradicate. Knowledge of the time and
mechanism of infection of the crop is essential for the devlop-
ment of an effective program for controlling a post-harvest
disease.
 Heating the surface of some fruits to a few degrees below the
injury threshold has been shown to eradicate or delay the
development of incipient infections. It is a relatively simple, low
cost method, leaving no chemical residues. Brief hot water treat-
ment does not increase refrigeration loan substantially because
only surface cells of produce are heated.

Measures to Reduce Post-Harvest Losses
Efficient Marketing System
 All factors remaining the same, the shorter the time between


harvest and consumption, the lower the post-harvest losses. An
efficient marketing system suiting the local conditions has to be
built and every link in the long marketing channel has to be given


very careful consideration. Speed is the most important single fac-
tor which affords access to increasingly remote markets and con-
sumer centers. Side by side, a suitable fruit processing line has to
be developed which could preserve the marketable surpluses,
culls and varieties not suitable for export or home consumption.




Improvement in Post-Harvest Handling Technique
 With the application of modern technology in grading, pack-
ing, transport and warehousing, a big breakthrough in the con-
servation of fruits and vegetables has been possible. Eventual
commercialization is carried out in packing plants located in the
production zone. It is now possible to transport highly perishable
commodities like grapes, lettuce, bananas, strawberries and
avocado pears to distant markets without an appreciable loss.
This, however, requires installation of modern, sophisticated
equipment requiring heavy capital investment. In some cases the
cost of transport and handling, etc., far exceeds the cost of pro-
duction. Post-harvest manipulations can only affect metabolic
transformation of chemical compounds already present, but any
imbalance will result in unsatisfactory post-harvest qualities.
 Temperature management is very important and is the first
step towards the conservation of fruits and vegetables. Cooling or
removal of field heat is a very effective means of achieving the
goal. By lowering the temperature, the rate of respiration is con-
siderably reduced as is the onset of post-harvest diseases.



Care During Preparation for the Market
 The exporting technique or post-harvest treatment used very
much depends on the geographical position and the require-
ments of the market.
 Production and marketing of produce can't be considered in
isolation. Protection of the produce should start right in the field,
i.e., immediately after harvest, and continue until the fruits are
consumed. Grading and standardization are important reference
factors in the world market. Sorting fruits by maturity and size,
and removing injured ones are therefore very important.
 Fruits mature in a relatively short space of time and if they are
harvested ripe they may have a very short post-harvest life. Some
fruits, like apples, oranges, etc., are waxed to seal in the freshness
and natural flavour and to give a good sheen.
 The produce should be stored in clean, lined bins or bins with
a smooth surface. Overfilling should be avoided. Fruits exposed
to the sun can attain a temperature many degrees above the air
temperature. The temperature attained depends upon the sur-
face, storage conditions and colour of the produce. If a tarpaulin
is to be used to cover the fruits during transport, it should be
clean, a light colour, and placed in a way to allow circulation of
the air so as to avoid warming the commodities. Occasional wet-
ting of the tarpaulin is also recommended. Field sanitation is
equally important. If flowing water is not used for washing, water
quickly gets polluted and in a short time develops a high concen-
tration of fungal spores which can further inoculate the injured
fruits.
 Excessive and indiscriminate dumping of fruits must be avoid-
ed at all costs as it leads to excessive injury. The grading or sorting
room should be well lit so that the workers can clearly see all the
fruits and remove the injured and defective ones. During pack-
ing, the fruit should be immobilized so as to avoid transit mo-
tion. This can be achieved by wrapping the fruit and carefully
packing it in the cartons, packing trays, padding, etc. Precautions
to safeguard fruits against impacts or compression should be
followed.


PROCEEDINGS of the CARIBBEAN FOOD CROPS SOCIETY-VOL. XX


280