INTRODUCTION
The fruit and vegetable sector has a vital role in farm income
enhancement, poverty alleviation, food security, and sustainable agriculture in
Asia, especially in developing countries. This sector, however, suffers greatly
from postharvest losses. Some estimates suggest that about 30–40% of fruit and
vegetables are lost or abandoned after leaving the farm gate. Huge postharvest losses
result in diminished returns for producers.
There are few types of post harvest losses such as decrease
of moisture content within the food stuff, damages, weight losses, quality loss
and seed viability loss. Currently, the main aim of the farmer is to increase
the production of fruits and vegetables and to ensure the sale of these items.
Relatively little consideration is given to the postharvest quality of these
fresh produce items.
In Sri Lanka, the institute of Post Harvest
Technology says, around 270,000 tonnes of fruits and vegetables are lost during
post harvest operations. The value of this loss is around Rs 9,000 million, per
year. Poor post harvest handling during storage, improper packaging and
transportation, diseases and inadequate storage facilities are some of the
major reasons for such high post harvest losses.
In
Sri Lanka, it has been estimated that post harvest loss of fresh produce vary
between 30 to 50 percent of the total production at any point between farmer
and consumer in the supply chain, depending on the commodity. Poor post harvest
handling during storage, improper packaging and transportation, diseases and
inadequate storage facilities are some of the major reasons for such high post
harvest losses.
Postharvest losses are caused by both external and internal
factors,
External Factors Which Lead to Postharvest Losses
Mechanical Injury
Fresh fruits and vegetables are highly susceptible to
mechanical injury owing to their tender texture and high moisture content. Poor
handling, unsuitable packaging and improper packing during transportation are
the cause of bruising, cutting, breaking, impact wounding, and other forms of
injury in fresh fruits and vegetables.
Parasitic Diseases
The invasion of fruits and vegetables by fungi, bacteria,
insects and other organisms, is a major cause of postharvest losses in fruits
and vegetables. Microorganisms readily attack fresh produce and spread rapidly,
owing to the lack of natural defense mechanisms in the tissues of fresh
produce, and the abundance of nutrients and moisture which supports their
growth. Control of postharvest decay is increasingly becoming a difficult task,
since the number of pesticides available is rapidly declining as consumer
concern for food safety is increasing.
Internal Factors
Physiological Deterioration
Fruit and vegetable tissues are still alive after harvest,
and continue their physiological activity. Physiological disorders occur as a
result of mineral deficiency, low or high temperature injury, or undesirable
environmental conditions, such as high humidity. Physiological deterioration
can also occur spontaneously owing to enzymatic activity, leading to over
ripeness and senescence, a simple aging phenomenon.
POST HARVEST PRACTICES AND LOSSES AT THOSE STAGES
Handling
Cleaning and sorting
Cleaning and sorting the products are the one of important
practice which as carried out after the harvesting. Cleaning is important,
because some products such as carrot, potato, cassava, etc. can contain mud on
their surface or products can contain some unwanted products. There are some
losses also happening when cleaning because of lack of awareness or facilities.
We observe that farmers using water in low pressure and they are using their
leg for removing the mud from carrots (below picture will show that). So, there
are lots of chances for physical damaging, contamination of micro-organisms,
loss of weight, etc.
In
market places, producers and marketers doing the cleaning and sorting
procedures near the garbage and waste water (below images shows that). So,
there are lot of chances for contamination of micro-organisms which cause the
loss in fruits and vegetables.
When
considering about meat and fish, there are few parts (which cannot be consumed)
have to be removed from meat and fish. So, when removing these parts there is a
chance for loss of consumable meat also. In fish, there is also have to be
removed some parts from inside of the fish. So, there also have some chances
for losses of fish meat.
packaging
Most fresh produce ready for market is composed of large
numbers of small units of similar size which must be moved in amounts
conveniently handled by one person. This is best achieved by using containers
of capacities from 3 to 25 kg, up to dimensions of about 60 per 40 per 30 cm.
Some commodities (e.g. potatoes) may be marketed in 25 or 50 kg sacks, and
other large items, such as whole bunch of bananas, are moved without packaging.
Leafy vegetables can be sold loose or tied in bundles and not packaged.
But in our country, they are using baskets, sacks and trays
to carry produce to markets. These are usually of low cost, made from readily
available materials such as dried grass, palm leaves or bamboo. They serve the
purpose for fresh produce carried over short distances, but they have many
disadvantages in big loads carried long distances.
Packaging helps to decrease the post harvest losses but some
damages happening to packaged produce also. Those damages can be state by
different varieties,
From injuries
Cuts or punctures
Cause: sharp objects piercing package; splinters in bamboo
or wooden containers; staples or nails protruding in containers;
Effect: deep punctures or cuts in produce, leading to water
loss and rapid decay
Impact (shock)
Cause: throwing or dropping of packages; sudden starting or
stopping of vehicle, causing load movement; speeding vehicle on rough road;
Effect: bursting of packaging, bruising of contents
Compression (squeezing or squashing)
Cause: flimsy or oversized containers; containers overfilled
or stacked too high or both; collapse of stacked containers during transport;
Effect: bruising or crushing of contents.
Vibration (shaking)
Cause: vibration of the vehicle itself and from rough roads;
Effect: wooden boxes come apart, damaging produce
From the environment
Heat damage
Cause: exposure of packages to external heat, e.g. direct
sunlight, or storage near heating system; natural buildup of internal heat of
produce owing to poor ventilation within package, in storage or vehicle;
Effect: fruit becomes overripe or softens; produce wilts and
develops off-flavours; decay develops rapidly; cardboard cartons may become dry
and brittle, easily damaged on impact;
Chilling or freezing damage
Cause: low or subzero ambient temperatures; exposure of
sensitive produce to temperatures below chilling or freezing tolerance level
during storage;
Effect: damage to chilling-sensitive produce; breakdown of
frozen produce on thawing; plastic containers become brittle and may crack;
Moisture and
free-water damage
Cause: exposure to rain or high humidity; condensation on
packages and produce moved from cold store to damp atmosphere at ambient
temperature; packing wet produce in cardboard containers;
Effect: softening and collapse of stacked cardboard
containers; squashing of produce in collapsed containers; decay promoted in
damaged produce;
Damage from light
Cause: plastic sacks and crates not treated with an
ultraviolet inhibitor eventually break up when exposed to direct sunlight;
Effect: disintegration of plastic sacks damages produce when
it is moved; fracturing of plastic crates can cut or bruise produce;
From other causes
Chemical contamination
Cause: contamination of containers stored near chemicals;
damage to produce by containers treated with preservatives, e.g. boxes made
from wood treated with pentachlorphenate (PCP); contamination of produce from
boxes affected by mould growth;
Effect: flavour contamination or surface damage and
discoloration of produce in contact with container; decay of produce owing to
contaminating moulds; wood-rotting moulds cause collapse of boxes;
Insect damage
Cause: insects present in packed produce; wood-boring
insects in wooden boxes;
Effect: consumer resistance and legal problems from presence
of insects (e.g. spiders, cockroaches) in packed produce; spread of
wood-destroying insects in infected boxes;
Human and animal damage
Cause: contamination and eating by rodents and birds; pilfering
by humans;
Effect: rejection of damaged produce by buyers or
inspectors; loss of income through loss of produce.
Storage
In market places, fruits and vegetables are storing without
any heat treatment or micro-biological treatment. Especially bunch of bananas
were kept along the roads until selling. These behaviors can cause huge post
harvest losses.
Solutions for losses happening when handling
Cleaning and sorting
- Can use water in high pressure to remove the mud in some vegetables such as carrot, potato, cassava, etc.
- Have to increase the awareness of cleaners about the micro-biological damages happening to fruits and vegetables from garbage and waste water and cleaning process have to be under taken in good place with proper conditions.
- Use of some brushes or like those things will reduce the mechanical damages than using the legs to clean the fruits and vegetables and it will be easy.
Packaging
- Packaging should contain shock absorption material for fruits and vegetables, because they are perishable food stuff.
- Suitable packages, both from a technical and an economic point of view, for handling and transportation of fresh commodities are important. Rigid containers can be used, namely nestable plastic crate, collapsible plastic crate, collapsible steel crate, wooden box, fibreboard box and wax coated fibreboard box, the nestable plastic crate is the most suitable package type for handling and transportation of vegetables and fruits.
- Packagers should be well trained and they have to be aware of losses by mechanical injuries and environmental conditions when packaging.
Storage
- The lowest temperature that does not cause chilling injury is the ideal storage temperature for fresh fruits and vegetables.
- Store in proper place with free micro-organisms is good to keep the fruits and vegetables without loss.
- Use of control Atmosphere/Modified Atmosphere Storage.
Loading, transport and unloading
Loading and unloading are very important steps in the
postharvest handling of fruits and vegetables but are often neglected. The
individual handling of packaged produce in Sri Lanka leads to mishandling and
to high postharvest losses in Sri Lanka. With the introduction of plastic boxes,
serious consideration should be given to the introduction of palletization and
mechanical loading and unloading of produce particularly with the use of
fork-lift trucks, in order to minimize produce mishandling.
There are lots of fruits and vegetables are transporting
without any absorption material and even they are not loaded in layer method.
When loading the fruits and vegetables as layers, the loss happening by
mechanical injuries also less (below picture will shows that). And loading and
unloading is carried out by co-workers, so they are handle them in hardly
manner when loading and unloading. They are not using any proper method because
of lack of proper packaging.
Railways and roads are two important transportation systems
for the movement of goods in Sri Lanka. Roads are that much good in village
areas, over load and high speed are lead to the post harvest losses. Without
proper loading such as layers wise, those conditions will dangerously lead to
high loss in fruits and vegetables.
Solutions for losses happening when loading, transport and unloading
- Can use the railway transport in order avoid the bad road conditions, avoid high cost when using boxes and over load.
- Can load the fruits and vegetables as layers.
- Speed of vehicle and the quantity of load have to be in a limit.
- Can use the boxes or such a proper packaging method (described above) in order to make proper loading and unloading and also decrease the mechanical damages.
- Using of shock absorption materials when transporting without packaging.
- Can use mechanical loading and unloading methods.
Marketing
In market place, there are lot of witness for losses of
fruits and vegetables there. Some sellers place the fruits and vegetables in
roads and they are sorting out or selling. In some cases, they are placing
these at the height which is equal to the vehicles silencer height. This can be
leading the deposit of Pb in fruits and vegetables. And they are handling them
in hardly manner such as throwing and dropping. These activities will lead to
mechanical damages and also micro-biological effects. Not only fruits and
vegetables, but fish also handling in this hardly manner. Can saw some big
fishes dropped in ground.
And also there are lot of disappearing of fruits and
vegetables. Because they doesn’t consider about leaving small amount when
handling huge amount of fruits and vegetables. So, there are lot of vegetables
dropped in ground in market places.
Solutions for losses happening when marketing
- Increase the marketers’ awareness about post harvest losses and handling of proper methods is the one of good way.
- Prohibit keeping the fruits and vegetables in roads or selling them in platforms.
- Instruct the marketers about hardly handling and mechanical damages of fruits and vegetables.
References:
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ochaonline.un.org
