FRUITS AND VEGETABLE PACKAGING

Fruits and vegetables are living organisms even after harvesting; they can remain fresh only as long as normal metabolism continues. Metabolism involves absorption of oxygen which breaks down the carbohydrates in the product to water and carbon dioxide. If the availability of oxygen is restricted, the chemical reaction changes and small quantities of alcohol are produced. This results in off-odours and flavours and breakdown of plant cells.

This series of events is called anaerobic decay and can spoil fruits or vegetables within a few hours. Fruits and vegetables have very high moisture content, ranging from 75-95%. Their equilibrium relative humidites are as high as 98%. Under any normal atmospheric condition, they will dry rapidly. This causes wilting and shriveling due to loss of rigidity and shrinkage of the cells.

Proper packaging can prolong the storage life of fresh fruits and vegetables by preventing moisture loss and thereby wilting. The rate of moisture loss varies with the product and water vapour permeability of the packaging film. The use of small perforations for oxygen permeation has an insignificant effect upon moisture loss.

A type of spoilage much prevalent in fruits and vegetables is that caused by microorganisms such as yeasts, molds, and bacteria. These organisms can cause destruction by growing on the exterior of the product or they may invade the interior through a surface bruise or cut and cause internal decay. Therefore careful handling and packaging are very important in preservation of freshness and quality.

Normal ripening of fruits and vegetables causes alterations in colour, texture, odour and flavour. At some point, for each type, ideal ripeness is achieved. Beyond that point, the product becomes overripe and quality deteriorates. The primary goal of fresh produce merchandising is to deliver the product to the consumer at such a point in the ripening scale, that it will achieve perfect ripeness at time of eating. This of course is extremely difficult to do. In practice, the produce is delivered somewhat underripe at the time of purchase and the consumer delays consumption until ripening is completed.

Since all these processes are highly sensitive to temperature, they can be slowed down by storing the produce under refrigeration. Each fruit or vegetable has an ideal temperature for storage. If this temperature is not used, deleterious result occurs—for example, tomatoes will not ripen if chilled below 4°C, bananas will turn black below 11°C and potatoes develop a sweet flavor below 4°C.

An additional reason for the necessity of refrigeration for fresh produce is the heat generated due to metabolism or respiration. For example, green beans, sweet corn, broccoli, green peas, spinach, and strawberries generate from 15,000 to 50,000 Btu of energy per ton per 24 hours of storage at 15°C. Even when chilled to 0^o – 4^oC, they still evolve 2,500-17,000 Btu per ton per 24 hours. This heat must be taken into consideration in the design of refrigeration equipment.

Some types of fresh produce give off volatile compounds during ripening which will impart unacceptable odour and flavour if not allowed to escape, or they may prematurely ripen the fruit.

APPLICATIONS OF PACKAGING

The particular type of package used depends upon the shape and perishability of the product. There are five main classifications— soft fruit, hard fruit; stem products; root vegetables; and green vegetables. Soft fruits are highly perishable and easily subject to anaerobic spoilage. They bruise and crush easily which leads to rotting. They are packaged in semi-rigid containers with a cover of cellophane, cellulose acetate, polystyrene or other suitable film cover.

Sometimes, polyethylene bags with ventilation holes are used. Adequate ventilation is a must to avoid fogging. Handling must be gentle and avoided as much as possible. Shelf-life is limited due to individual damage and decay. Some berries under ideal conditions only retain top quality for 2 or 3 days. Typical soft fruits are cherries, grapes, blueberries, strawberries, raspberries and plums.

Hard fruits are better able to resist damage from handling. They are also less perishable and have lower respiratory rates. Shelf-life is weeks rather than days. The most common package is an open tray, a plastic film overwrap or sleeve. Hard fruits may also be bagged in perforated polyethylene film or in nets. Examples of hard fruits are apples, bananas, citrus fruits, peaches, pears and tomatoes.

Stem products are highly perishable as they rapidly lose moisture. They should be bagged or wrapped in moisture proof cellophane or polyethylene with ventilation, or they should be banded or sleeved with shrink film. Typical stem products are celery, rhubarb, and asparagus. Root vegetables are not highly perishable.

They can be stored for long periods; however, it is desirable to protect them against moisture losses. They are washed, graded and sized prior to packaging, which is usually in durable polyethylene bags with perforations. Typical root vegetables include carrots, turnips, radishes, onions, beets, yams and potatoes.

TYPE OF PACKAGING

Packaging can be classified in a number of ways; the most important one is by stages of distribution system for which it is primarily intended.

• Consumer or unit packaging,
• Transport packaging;
• Unit load packaging.

CONSUMER PACKAGING

The package in which consumer receives the produce is called consumer packaging. The term prepackaging of produce refers to consumer units prior to its presentation to the final consumer. Prepackaging may be undertaken at any stage throughout the distribution chain from the field to the retailer's premises, depending upon the need of produce for protection, expected transport and storage time, required shelf life, packaging material costs and costs of packaging and sorting at different points, transport and storage cost and latest knowledge of the market requirements.

Types of Consumer Package

Bags

Bags are the most common and favoured retail packs because of their low material and packaging cost. In terms of cost to strength ratio, 25-40 mm low density. Grapes in ventilated pouch polyethylene or 12.5 mm high density polyethylene bags are most suited. Net bags are used to provide desired ventilation and allow free air movement for the produce such as citrus fruits, onions, potatoes, etc. The bags can be made of paper, perforated polyethylene or polypropylene film, plastic or cotton nets.

Tray

Tray packs made of foamed polystyrene or PVC or PP are overwrapped with heat shrinkable or stretch films. A tight wrap immobilizes the fruits and keeps them apart. Trays of moulded pulp, card board, thermoformed plastic or expanded polystyrene are also used.

Sleeve Packs

These combine the low cost of bags and protective qualities and sales appeal of tray packs. Wraps of plastic film such as polyethylene or PVC, in the form of shrink-wrap, stretch film or cling film and regular net stocking or expanded plastic netting can also be used. The traditional fruits and vegetable retail trader packs the produce in the presence of consumers in the qualities and quantities required by them. The package normally used is a simple wrap of paper or a paper or polyethylene bag. Sleeve packs can be fabricated to contain from one to as many as ten fruits. The main advantage in sleeve packs is that they immobilize the produce at a fraction of cost of tray packs and the produce can be seen from all sides without damage to the fruit.

Transport packaging

Transport packaging for fresh produce may be divided into two size groups:

1. The predominant size group, suitable for carrying by man, is in the range of 15 to 25 kg.
2. The other group, recently becoming increasingly popular in 200-500 kg range suitable for fork lift handling is referred as pallet container.

Wooden Boxes

Includes natural wood and industrially manufactured wood-based sheet materials. Timber used must be inexpensive and easily worked. All wood that is used for the production of the packaging should be well dried in order to prevent cracks and mould growth later. Manufactured wood based sheet materials include ply wood, hard board and particle board. Plywood is usually made from birch. It is rigid and strong, though perhaps somewhat less resistant to splintering than poplar, but is smoother and flatter to be suitable for direct printing. Hard board is dark in colour but its appearance can be improved with decorative printing, but deforms after long storage in high relative humidity. Particle board is thicker and rigid but relatively brittle.

Corrugated Fibreboard Boxes

Corrugated fibreboard (CFB) boxes are the most commonly used shipping containers where cartons, glass, cans and pouches are the unit containers. The popularity of CFB box as a container in food industry as well as in other industrial packaging is for the following reasons:

• Low cost to strength and weight ratio.
• Smooth and non-abrasive surface.
• Good cushioning characteristics.
• Excellent printability.
• Easy to set up and collapsible for storage,
• Reusable and recyclable market.

Plastic Corrugated Boxes

The most commonly used material for plastic corrugated box is polypropylene and HDPE. Its advantage over CFB is low weight to strength ratio and its reusability. The printability is also excellent when compared to CFB boxes. But CFB box has an edge over plastic fibreboard boxes when cushioning properties are taken into consideration. The disadvantages are ultraviolet degradation and temperature resistant, which can be taken care by use of additives.

Plastic Crates

Plastic crates, usually made up of HDPE or polypropylene by injection moulding have been replacing wooden and wire crates. These crates must have good resistant properties to ultraviolet degradation and shock damages.

Sacks

These are flexible shipping containers which are generally used in food industries to transport raw materials viz. fruits and vegetables from the field. If the weight of content is more than 10 kg then it is called sack otherwise bag. The commonly used materials for sacks are cotton, jute, flan, woven plastics (HDPE, Polypropylene). These sacks are advantageous to use as they cost less, have high strength, reusable and require little space for the empties. Disadvantage of plastic woven sack is poor stack ability due to low coefficient of friction, which can be overcome by making antis lip bags.

Palletization

Pallets have been standardized keeping in view of the standard package sizes and sea containers. The sizes of the pallets are of strategic importance since they correspond directly to the sizes of various types of containers, ship cargo compartments, trucks, fork trucks, etc. Most commonly used pallet sizes are 120x80 cm (Euro pallet) and 120x100 cm (Sea pallet). Reusable plastic pallets are in use. They are made up of HDPE or polypropylene. They are easy to clean and light in weight as compared to wooden pallets. Palletized loads are used in order to reduce handling costs by allowing substitution of mechanical handling for manual methods with the following advantages:

• A decrease in sorting operations.
• Reduced labelling requirement.
• Better utilization of storage space.
• A reduction in mechanical strains and damages.
• A reduction in total distribution time.
• Better maintenance of product quality.
• Two principles are used in the assembly of pallet loads.
• The modular principle, in which all packages are oriented in the same direction.
• The two-way principle, in which the packages in each tier form a pattern such that some packages are oriented lengthwise and others cross-wise on the pallet.

Unitization

Corner posts made of plastic or wood or moulded paper boards are generally used as columns for unitization. The boxes are held together by means of strapping or stretch wrapping around the boxes. The strapping is of polypropylene.

NEW TRENDS

Several new technologies offer the packer opportunities to modify the atmosphere inside the shipping package during distribution even though such control traditionally finishes with the sealing of the package. Packaging is termed as “active” when it performs some desired role other than to provide an inert barrier to the external environment.

The goal of developing such packaging is the achievement of a more ideal match of the properties of the package to the requirements of the food. Hence, it addresses one or more specific needs of the food without necessarily having any impact on other food properties.

SOME TECHNOLOGICAL INNOVATIONS

Most applications of active packaging involve the use of polymers. The role played by the polymer may be that of a conventional packaging material as in the fabrication of sachets that are used commercially to scavenge oxygen or carbon dioxide, or to release ethanol or carbon dioxide. When the active agent is dispersed in a packaging film or sheet, as in OXYGUARD™ thermoformed trays (Toyo Seikan Kaisha, Japan), the polymer acts as a somewhat permeable carrier.

The polymer can play an even more active role when it interacts physically or chemically with the components of the headspace of the package. Such interactions include absorption as in the case of humidity buffering linings for produce cartons, or reactions as in the case of oxygen scavenging plastics.

Ethylene Scavengers

Ethylene (C2H4) acts as a plant hormone that has different physiological effects on fresh fruit and vegetables. It accelerates respiration, leading to maturity and senescence, and also softening and ripening of many kinds of fruits. Furthermore, ethylene accumulation can cause yellowing of green vegetables and may be responsible for a number of specific postharvest disorders in fresh fruits and vegetables.

Although some effects of ethylene are positive such as degreening of citrus fruit, ethylene is often detrimental to the quality and shelf life of fruits and vegetables. To prolong shelf life and maintain an acceptable visual and organoleptic quality, accumulation of ethylene in the packaging should be avoided. Most of these ethylene absorbers are supplied as sachets or integrated into films.

Potassium permanganate (KMnO4), which oxidizes ethylene to acetate and ethanol and in this process, colour changes from purple to brown indicating the remaining C2H4 scavenging capacity. Products based on KMnO4 cannot be integrated into food contact materials, but are only supplied in the form of sachets because KMnO4 is toxic and has a purple colour.

The silica adsorbs the ethylene and the permanganate oxidizes it to acetate and ethanol. Another type of C2H4 scavenging concept is based on the adsorption and subsequent breakdown of ethylene on activated carbon. Charcoal containing PdCl as a metal catalyst was effective at 200C in preventing the accumulation of ethylene, in reducing the rate of softening in mini-mally processed kiwifruits and bananas and in reducing chlorophyll loss in spinach leaves but not in broccoli.

Other C2H4 adsorbing technologies are based on inclusion of finely dispersed minerals such as zeolites, clays and Japanese oya into packaging films. Most of these packaging films, however, are opaque and not capable of adsorbing C2H4 sufficiently. Although the incorporated minerals may adsorb ethylene, they also alter the permeability of the films: C2H4 and CO2 will diffuse much more rapidly and O2 will enter more readily than through pure PE.

These effects can improve shelf life and reduce headspace C2H4 concentrations independently of any C2H4 adsorption. In fact, any powdered material can be used to reach such effects.

Active packaging employs a packaging material that interacts with the internal gas environment to extend the shelf life of a food. Such new technologies continuously modify the gas environment (and may interact with the surface of the food) by removing gases from or adding gases to the headspace inside a package.

Recent technological innovations for control of specific gases within a package involve the use of chemical scavengers to absorb a gas or alternatively other chemicals that may release a specific gas as required. The table below sets out some areas of atmosphere control in which active packaging is being successfully used.

Active Packaging System	Application
Oxygen scavenging	Most food classes
Carbon dioxide production	Most food affected by moulds
Water vapour removal	Dried and meld-sensitive foods
Ethylene removal	Horticultural produce
Ethanol release	Baked foods (where permitted)

Ethylene Scavenging

A chemical reagent, incorporated into the packaging film, traps the ethylene produced by ripening fruit or vegetables. The reaction is irreversible and only small quantities of the scavenger are required to remove ethylene at the concentrations at which it is produced. A feature of this system is its pink colour, which can be used as an indicator of the extent of reaction and shows when the scavenger is used up.

It is expected that the film will be produced and used as a valuable means of extending the export life of fruit, vegetables and flowers. These usually involve the inclusion in the package of a small sachet, which contains an appropriate scavenger. The sachet material itself is highly permeable to ethylene and diffusion through the sachet is not a serious limitation. The reacting chemical for ethylene is usually potassium permanganate, which oxidizes and inactivates it.

Oxygen Scavenging

The presence of oxygen in food packages accelerates the spoilage of many foods. Oxygen can cause off-flavour development, colour change, nutrient loss and microbial attack. Several different systems are being investigated to scavenge oxygen at appropriate rates for the requirements of different foods.

One of the most promising applications of oxygen scavenging systems in food packages is to control meld growth. Most moulds require oxygen to grow and in standard packages it is frequently meld growth, which limits the shelf life of packaged baked goods such as cakes and crumpets and of packaged cheese. Laboratory trials have shown that meld growth on some baked products can be stopped for at least 30 days with active packaging and significant improvements in the free-free life of packaged cheese have also been obtained.

Another promising application is the use of active packaging to delay oxidation of and therefore rancidity development in vegetable oils. Again the use of discrete sachets containing oxygen absorbents has already found commercial application. In this instance the scavenging material is usually finely divided iron oxide. These sachets have been used in some countries to protect the colour of packaged cured meats from oxygen in the headspace and to slow down staling and meld growth on baked products, e.g. pizza crusts.

This approach of inserting a sachet into the package is effective but meets with resistance among food packers. The active ingredients in most systems consist of a non-toxic brown/black powder or aggregate which is visually unappealing if the sachet is broken. A much more attractive approach would be the use of a transparent packaging plastic as the scavenging medium.

Humidity Control

Condensation or 'sweating' is a problem in many kinds of packaged fruit and vegetables. It is of particular concern in cartons of fresh flowers for which there is important export trade.

Unless the relative humidity around flowers is kept at about 98 per cent, water will be lost from the bunches. Such high humidity levels mean there is a very real risk of condensation occurring during transport as the temperature of the flowers may fluctuate by several degrees. When one part of the package becomes cooler than another, water is likely to condense in the cooler areas.

If the water can be kept away from the produce there may be little harm. However when the condensation wets the produce, nutrients leak into the water encouraging rapid meld growth.

When the condensation inside packages is controlled, the food remains dry without drying out the product itself. Therefore sensitive products such as flowers and table grapes are protected from contact with water. This helps to reduce growth of meld.

Carbon Dioxide Release

High carbon dioxide levels are desirable in some food packages because they inhibit surface growth of micro organisms. Fresh meat, poultry, fish, cheeses and strawberries are foods, which can benefit from packaging in a high carbon dioxide atmosphere.

However with the introduction of modified atmosphere packaging there is a need to generate varying concentrations of carbon dioxide to suit specific food requirements. Since carbon dioxide is more permeable through plastic films than is oxygen, carbon dioxide will need to be actively produced in some applications to maintain the desired atmosphere in the package.

Release of Microbial Inhibitors

Ethanol

Antimicrobial activity of ethanol (or common alcohol) is well known and it is used in medical and pharmaceutical applications. Ethanol has been shown to increase the shelf life of bread and other baked products when sprayed onto product surfaces prior to packaging.

A novel method of generating ethanol vapour, is through the use of an ethanol releasing system enclosed in a small sachet which is included in a food package. Food grade ethanol is absorbed onto a fine inert powder which is enclosed in a sachet that is permeable to water vapour. Moisture is absorbed from the food by the inert powder and ethanol vapour is released and permeates the sachet into the food package headspace

Sulfur Dioxide

Sulfur dioxide is primarily used to control meld growth in some fruits. Serious loss of table grapes can occur unless precautions are taken against meld growth. It is necessary to refrigerate grapes in combination with fumigation using low levels of sulfur dioxide.

Fumigation can be conducted in the fruit cool stores as well as in the cartons. Carton fumigation consists of a combination of quick release and slow release systems, which emit small amounts of sulfur dioxide.

When the temperature of the packed grapes rises due to inadequate temperature control, the slow release system fails releasing all its sulfur dioxide quickly. This can lead to illegal residues in the grapes and unsightly bleaching of the fruit.

Considerable amount of work is done to develop systems, which gradually release sulfur dioxide and are less sensitive to high temperature and moisture than those presently used. These systems have potential use for fresh grapes and processed foods permitted to contain sulfur dioxide such as dried tree fruits and wine.

Other Developments

Other systems of active packaging which are either already available or could soon be seen in the market place include:

• Sachets containing iron powder and calcium hydroxide, which scavenge both oxygen and carbon dioxide. These sachets are used to extend the shelf life of ground coffee.
• Film containing microbial inhibitors other than those noted above. Other inhibitors being investigated include metal ions and salts of propionic acid.
• Specially fabricated films to absorb flavours and doors or, conversely, to release them into the package.

GRAIN (RICE) STORAGE AND PEST CONTROL

Rice storage facilities take many forms depending on the quantity of grain to be stored, the purpose of storage, and the location of the store. In general, it is recommended that rice for food purposes be stored in paddy form rather than milled rice as the husk provides some protection against insects and helps prevent quality deterioration. However, when rice can be stored as brown rice, 20% less storage capacity will be needed.

• The requirements for a good storage system include:
• Prevention of moisture re-entering the grain after drying
• Protection from insects, rodents and birds
• Ease of loading and unloading.
• Efficient use of space
• Ease of maintenance and management.

Rice grain is hygroscopic and in open storage systems the grain moisture content will eventually equilibrate with the surrounding air. High relative humidity and high temperatures contribute to high equilibrium or final moisture content. In many tropical countries, the equilibrium moisture content is above safe storage moisture levels.

SAFE STORAGE CONDITION OF GRAINS

Safe storage of rice for longer periods is possible if three conditions are met:

•        Grain is maintained at moisture levels of 14% or less and seed is stored at 12% or less
•        Grain is protected from insects, rodents and birds
•        Grain is protected from re-wetting by rain or imbibing moisture from the surrounding air.

The longer the grain needs to be stored, the lower the required moisture content will need to be. Grain and seed stored at moisture contents above 14% may experience the growth of molds, rapid loss of viability and a reduction in eating quality. The following table shows the ‘safe’ moisture content required for different storage periods.

Storage period	Required moisture content for safe storage	Potential problems
2 to 3 weeks	14 – 18 %	Molds, discoloration, respiration loss
8 to 12 months	12- 13 %	Insect damage
More than 1 year	9 % or less	Loss of viability

A rule of thumb for seed is that the life of the seed will be halved for every 1% increase in moisture content or a 5oC increase in storage temperature.

GRAIN STORAGE SYSTEMS

Grain storage systems can be classified as either bag or bulk.

Bag storage system.

In most parts of Asia grain is stored in 40-80kg bags made from either jute or woven plastic. Depending on the size of storage, these bags are normally formed into a stack. When using bag storage consideration needs to be given to the following:

• Jute bags should not be stacked higher than 4m and plastic bags 3m. Plastic bags are more slippery and the stacks will be less stable
• Bags should be stacked under cover e.g. under a roof, in a shed or granary or under water proof tarpaulins
• A one meter gap should be left between and around stacks and 1.5 meters clearance between the top of the stack and the roof
• Bags should be stacked on pallets or on an above ground structure to avoid the possibility of absorbing moisture from the floor.
• Bags should not be stacked on a bed of rice husks or bags filled with rice husks, as these are difficult to keep free from insect infestation.
• Bags should be stacked so that fumigation can be undertaken easily. The dimensions of the stacks should be set to facilitate sealing with a single fumigation sheet.
• The efficiency of bag storage can be improved if a plastic liner bag is used inside the existing storage bag especially for seed and milled rice

Some farmers use bag storage in outside granaries, which have been constructed from timber or mud/cement or large woven bamboo or palm leaves.

Bulk storage

At farm level grain is often stored in bulk in small outside granaries or in woven baskets or containers made from wood, metal or concrete, which are located under or inside the house. These storages vary in capacity from 200-1000kg. Losses from insects, rodents, birds and moisture uptake are usually high in traditional bulk storage systems.

The large export mills and collection houses sometimes use metal or concrete silos. These silos range in size from 20 to 2,000 ton capacity. Silos have the advantage that they can be more easily sealed for fumigation and less grain is spilt or wasted. Bulk storage warehouses are not very common in Asia.

Hermetic Sealed storage

Sealed or hermetic storage systems are a very effective means of controlling grain moisture content and insect activity for grain stored in tropical regions. By placing an airtight barrier between the grain and the outside atmosphere the moisture content of the stored grain will remain the same as when the storage was sealed. The moisture content of the grain will then determine the relative humidity level inside the storage unit.

 

Respiration by the grain and insects inside the storage, change the inter-granular atmosphere by consuming oxygen and expiring carbon dioxide. Depending on the number of insects, and type and size of the system, oxygen levels will be reduced from 21% to less than 10% within a short period of time. At oxygen levels below 10%, insects are curtailed and the viability of seed doubled i.e. from 6-12months .

Sealed storage containers come in all shapes and sizes. They may range from a small plastic container, a sealed 200-liter drum to the more complex and costly sealed plastic commercial storage units. Recent technological advances in plastic manufacturing have led to the development of PVC liners that provide the required durability to climate, gas permeability and physical properties that enable airtight storage for extended periods of time.

For storage of small seed lots a variety of plastic bags or packages can be used. Different types of plastic have different resistance against transmission of water vapor. Glass jars, hard PVC or bags containing aluminum liners or a gas barrier will provide the best protection against moisture re-entry. Polypropylene or polyethylene bags are the next best choice. Paper bags or flexible PVC bags for long-term storage of seed is not advisable.

Storage capacity

Different grains and components of grain have different weights. The following Table gives the approximate weight and volume for paddy rice and its milled components.

	Bulk (kg/m3)	Bag (bags/ton)	Weight per bag
Paddy or rough rice	600-650	13-20	50-80 kg
White rice	850-900	20-25	40-50kg
Bran or meal	550-600	20	50kg
Husk	120-140

To determine the storage capacity for different types of storages the following equations may help

• Square or rectangular bin:Volume = (length x width x height) x bulk density (kg/m2)
• Tower silo with flat bottomVolume = (22/7 x radius x height) x bulk density (kg/m2)
• Tower silo with cone bottom:Volume cylinder= (22/7 x radius x height) + volume of cone = (1/3 (22/7 x height)) x bulk density (kg/m2)
• Grain pile on a padVolume (length x width x 0.73 (grain coefficient))

In many storage devices allowances must be made for the angle of repose of grain (angle on the top of the grain stack). The angle of repose for rice, which is allowed to freely fall into a pile, is approximately 36 degrees.

Storage Hygiene

Good hygiene in the grain store or storage depot is important in maintaining grain and seed quality. Guidelines for hygiene in the grain store include:

• Keep storage areas clean. This means sweeping the floor, removing cobwebs and dust, and collecting and removing any grain spills.
• Clean storage rooms after they are emptied and this may include spraying walls, crevices and wooden pallets with an insecticide before using them again
• Placing rat-traps and barriers in drying and storage areas. Cats deter and help control rats and mice
• Inspect storage room regularly to keep it vermin proof.
• Inspect the stored seeds once a week for signs of insect infestation. When necessary and only under the direction of a trained pest control technician, the storage room or the seed stock may be sealed with tarpaulin and treated with fumigants.

MAJOR STORAGE PESTS IN RICE

      Rice storage pests include insects, pathogens, rodents and birds. These pests cause losses through a combination of feeding, spoiling and contamination of both paddy and milled grain.

      Insects

      Environment

     Each insect species has its own optimum temperature development as well as a preferred feeding habit. The optimum temperatures for most insect species range between 25 and 32°C. At temperatures below 14°C and above 42°C, the rate of development is reduced and most storage pests will die at temperatures below 5°C and above 45°C.

     The optimum relative humidity for most species is around 70%, with the minimum 25 - 40% and the maximum 80 - 100%. Very few species are able to survive in extremely dry conditions.

      Under good conditions, the duration of the development cycle from egg to adult is 18 - 25 days for beetles and 28 - 35 days for moths. In unfavorable conditions, this period may be extended to several months.

      Insect activity and fertility are also affected by the change in light. Moths are most active at dawn and at dusk. Inspections to check and control flying insects are best made at these times. Artificial light can help to reduce the movement and fertility of moths. Most storage pests are able to penetrate a stack of bags more quickly and thoroughly than bulk grain because of the gaps between the bags. The size, the surface texture and nutrients in the grain also influence the ability of the pest to attack the grain.

      Insect Species

      While many different species of insects are found in rice only a few are major pests. Insects in stored rice can be classified as either primary or secondary insects.

      Primary Insects: These are insects whose larvae feed entirely within the kernels of the grain. These include the rice weevil, angoumois grain moth and lesser grain borer.

      Rice Weevil (Sitophilos oryzae (Linnaeus)): Adults and larvae feed on a wide variety of grains and a female can deposit up to 150 eggs. A single egg is laid in each grain after boring a hole inside. The egg stays in the grain until it becomes an adult, and this completely damages the grain. The life cycle takes approximately 35 days under good conditions such as 28 °C and 70% relative humidity.

      Angoumois Grain Moth (Sitatroga cerealella (Olivier)): Eggs are laid on or the near grain. The white larvae bore into the kernels of the grain and feed on the inside. When the larvae mature they eat their way to the outer portion of the grain, leaving only a thin layer of the outer seed coat intact. Pupation takes place just under the seed coat. When the adult emerges from the grain, it pushes aside the thin layer of seed coat leaving a small trap door covering its exit point from the kernel. They infest only the surface layer of bulk-stored grain, as adults are unable to penetrate deeply.

      Lesser Grain Borer (Rhyzopertha dominica (Fabricus)): The eggs are laid in the grain mass and the larvae may enter the kernels and develop within or they may feed externally in the flour-like dust that accumulates from the feeding of the adults and other larvae. The optimum temperature for reproduction is 34°C and the optimal relative humidity is 60 -70% Females lay 300 - 500 eggs and the life cycle lasts 20 - 84 days

      Secondary Insects are insects that feed from the outside of the grain even though they may chew through the outer coat and devour the inside. Two of the more prevalent secondary insects are the Saw-toothed Grain Beetle and the Rust-red flour beetle

      Saw-toothed Grain Beetle (Oryzaephilus surinamensis (Linnaeus)): Eggs are usually laid, either singly or in small masses in a crevice in the grain but in products such as flour they are laid freely.

      Rust-red flour beetle (Tribolium castaneum): The red flour beetles primarily attacks milled grain products. Both adults and larvae feed only on the grain dust and broken kernels and do not attack the undamaged whole kernels. Infestation leads to persistent and disagreeable odors of the rice. The optimum temperature for reproduction is 35°C and a relative humidity of 75%. The red flour beetle can lay up to 500 eggs and has a life cycle of 20 days under optimum conditions

     MANAGEMENT OF STORAGE INSECTS

     The management of stored grain pests should be done in a sequential and integrated manner. An effective pest control system involves

• Harvesting, drying and storage of clean dry grain
• Disinfecting the storage system and
• Controlling or preventing pest infestation during the storage period.

      Harvesting, drying and storage

      Grain must be dried to at least 14% moisture (wet basis) and seed grain should be dried to12% moisture before storage. Grain needs to be harvested and dried so that it will not cause cracking of the grain, as cracked grains are easier for insects to infest.

      This requires:

• Harvesting and threshing at the correct stage of maturity (20-25% moisture content)
• Drying the grain at a rate and temperature that will not damage the grain. The first stage of drying from 25% moisture to 18% can be done at high temperatures e.g. above 50-60oC. After this the grain needs tempering or cooling for at least 4 hours. Drying from 18% to 14% moisture should be much slower and the temperature should not exceed 42oC.
• When sun drying, the grain should be spread in thin layers, 2-5cm, and turned every 1-2 hours. When sun-drying seed, the grain should be turned more often and not exposed to temperatures above 42oC. If high temperatures occur the seed should be dried in the shade.

     New grain should not be stored near older grain unless all insects have been eliminated from the older grain. It is preferable to store grain as paddy or rough rice as this is less susceptible to insect attack than milled rice. Parboiled rice is also less susceptible to damage than raw rice.

      Grain stores must have a damp proof floor and have waterproof walls and roof. It is preferable to be able to seal the storage so fumigation is possible should the need arise. Sealing the storage also helps exclude rodents and birds. Where grain is to be stored in bags, the bags should be stacked on pallets at least 50cm away from the walls. Hermetic storage systems have proved to be an effective means of storing grain.

      By having a sealed atmosphere the insects utilize the O2, expire CO2 and eventually die through suffocation and dehydration. This will occur within 5-10 days depending on the level of insect infestation. Other benefits of a hermetic system are that the moisture content of the grain and storage environment remains constant, and the sealed system reduces the chance of damage by rodents and bird.

      DISINFESTING THE STORAGE SYSTEM

      Disinfestations require a systematic and thorough cleaning of all sources of infestation before storage. Old grain residues in the storehouses, grain bins, harvesting and threshing equipment should be treated, removed or destroyed.

      Storage containers, structures and equipment can be treated with:

• Malathion (50EC) at 5ml/20l of water @20ml/m2
• Fenitrothion (50EC) at 5ml/l water @20ml/m2
• Deltamethrin (2.5% WP) at 1.5g/l water @20ml/m2

      If thorough cleaning of containers is not possible, the containers may need to be sealed and fumigated with phosphine. All second hand bags should be examined and where necessary treated with either a fumigant, insecticide or dipped in boiling water. Solutions of Malathion (50EC) and Fenitrothion (50EC) at 5ml/20l of water and Deltamethrin (2.5% WP) at 1.5g/l water @20ml/m2 can be used for dipping the bags.

      CONTROLLING INFESTATIONS WITHIN THE GRAIN

      Consumers are increasingly demanding grain that is free from live insects and free from chemical residues caused by controlling pests. While many chemical sprays are registered for rice, some markets will not accept grain treated with these registered chemicals. Farmers should always check with buyers to ensure that the pest control methods intended for use will be acceptable.

      The first step in controlling any infestation is to determine the level of infestation and then select an appropriate method for control. All storage should be checked, preferably every fortnight, and at least monthly. Random samples need to taken from all grain and tested for infestation. If there are more than 4 insects per kg some form of treatment is required. A simple rule of thumb for the number of bags to be sampled is to use the square root of the lot size. For example if there are 100 bags in the lot, samples should be taken from 10 bags.

      Grain treatments

      It is not recommended to use synthetic insecticides with rice that is for consumption. Only chemicals registered for direct application to rice grain should be used and these should be applied according to the label.

      Malathion is a widely used chemical and is toxic to insects if it comes into direct contact with the pest. Malathion is considered one of the safest organophosphate insecticides as it is not highly toxic to humans or pets, and breaks down fast under tropical conditions. Malathion will not penetrate piles of grain. Although it is not usually recommended, it is still legal to treat grain with Malathion at 8 parts per million concentrations.

      As a grain treatment Malathion is applied at the time grain is stored. Treated grain should not be sold for at least 7 days nor eaten within 60 days of treatment. Safety precautions must be observed when applying Malathion or any other chemical.

      Fumigation

      Fumigants are effective against storage pests because as gases they can reach the pests in the most remote hiding place. The range of safe fumigant chemicals that can be used is now restricted to phosphine and carbon dioxide.

      Phosphine fumigation

      Phosphine fumigation is undertaken using tablets and pellets. These tablets and pellets release phosphine gas when they come into contact with humid air. Phosphine is toxic to all insects. When insects are exposed to fumigation in a sealed environment all stages of development from the eggs, larvae, pupae to adults are killed. Phosphine does not impair the grain nor leave residues that could be hazardous to the consumer when correctly applied and the grain aerated. Care must be taken when using phosphine as a gas as it is very toxic to humans. Fumigation must take place in an enclosure that can be tightly sealed. Once the exposure time is ended, the grain must be aerated and the bin checked for residual phosphine gas before entry.

      dioxide fumigation

      Insects need oxygen for respiration. With carbon dioxide fumigation, much of the oxygen in the storage bin is replaced by carbon dioxide that suffocates, dehydrates and also produces toxic chemicals in the blood of the insects. To be effective, elevated carbon dioxide levels must be maintained until all insects die. The required exposure time depends on the percentage of carbon dioxide and the temperature of the grain. The cost of CO2 fumigation is high.

      Physical conditions

      Temperatur
      The ideal temperature for stored product insect growth is 25-30oC. The lower the grain temperature the slower the insect populations increase. Aerating the grain immediately after harvest so the grain is cooled will significantly reduce insect infestation. At 15oC the insects stop laying eggs and development stops. At lower temperatures insects will die.

      High temperatures will also kill all stages of insects (eggs, pupae, larvae and adult) if exposed for a sufficient period of time. The most realistic use of high temperature is at drying or in some instances when the grain is being removed from storage for sale. Generally insects need to be exposed to temperatures of 50-55oC for at least 15 minutes.

      Impact

      Certain insects are vulnerable to the physical impact caused by moving grain. Pneumatic conveyers subject the grain kernels to large forces and operate at high pressure. As insects go through the pneumatic conveyer they are killed. Like high temperature this method may be useful when the grain is being moved for sale.

      Diatomaceous earth

      Control of some insects (e.g. rusty grain beetle) can be achieved by using a non-toxic dust made from prehistoric diatoms. When the insect comes in contact with this dust, the waxy covering on the exoskeleton is absorbed, leaving them prone to dehydration and death. The product is applied as the grain is loaded into the bin and is most effective when applied to dry grain at harvest. Control can take up to 5-6 weeks.

      FUNGI IN STORED RICE

      Contamination of seed and grain with fungal organisms may result in poor germination, seedling vigor or grain quality. Storage fungi usually invade grain or seed during storage and are generally not present in large quantities before harvest in the field. The most common storage fungi are species of Aspergillus and Penicillium.

      These fungi are widely distributed and almost always present. Contamination occurs through small quantities of spores contaminating the grain as it is going into storage from the harvest, in handling and storage equipment or from spores already in the storage structures. Under high temperatures and moisture this small amount of inoculum can increase rapidly. The development of fungi is influenced by the:

• Moisture content of the stored grain
• Temperature
• Condition of the grain going into storage
• Length of time the is grain stored and
• Amount of insect and mite activity in the grain.

      Fungi cause two distinct problems in storage grains. These are grain spoilage from fungal growth or molds and the production of poisonous mycotoxins. Grain spoilage causes poor germination, loss of weight, loss of nutritive value, poor milling quality and deterioration in flavor and color of the rice. While the losses from spoilage may be of greater economic significance, they are less dangerous than the presence of mycotoxins. Mycotoxins are poisonous chemical compounds produced by certain fungal species that infect crops. While these fungi are not common in rice they have been isolated from rice.

      Management Options

      Safe Storage Conditions

      Grain damage by fungi will be reduced when grain and seed is:

• Stored at moisture contents below 13-14%. It is important to be aware that there is variation in moisture content through a grain mass and fungi will grow where moisture is suitable and not according to the average moisture content of the grain stack
• Stored at temperatures below 20^oC and above 40^oC.
• Not cracked and broken kernels or contain large amount of foreign material - broken or cracked kernels are more likely to be contaminated going into storage and more likely to be invaded once they are in storage than whole kernels.
• Free from fungi coming into store. Grains moderately invaded by storage fungi develop damage at lower moisture content, at a lower temperature and in a shorter time period than grain free or almost free of storage fungi.
• Stored for a shorter period. Grain that is to be stored for only a few weeks before processing can be stored safely with a higher moisture content and more extensive invasion by storage fungi and can be kept at a higher temperature than grain that is to be stored for months or years.
• Free from insect and mites. Insects and mites can carry fungal spores on their bodies thus introducing storage fungi into the grain mass. Insect activity in a grain mass leads to an increase in both the temperature and moisture content of the grain surrounding the insect infestation. In these 'hot spots' conditions may be favorable for mold growth.

      Grain treatment

      Infected seeds can be treated by either physical or chemical treatments, or a combination of both methods. Seed borne bacteria can be treated by dry heat at 65oC for 6 days or dipping in hot water treatment at 52-55oC.
      Seeds can also be treatment with fungicides such as Dithane M-45 and Benlate at the rate of 3 grams kg^-1. The most effective method of treating mycotoxin problems is avoidance. This is possible by drying the grain to a safe moisture content before storage, reducing physical damage to the grain during harvesting and storage and ensuring clean, dry insect-proof storage conditions.

     Minimize Damage

     Little can be done to prevent or reduce the invasion of crops in the field by fungi. However, the following recommendations should help prevent storage fungi problems or minimize damage from storage fungi in stored grains.

• Harvest as soon as the moisture content allows for minimum grain damage.
• Adjust the harvesting equipment for minimum kernel or seed damage and maximum cleaning.
• Clean all grain harvesting and handling equipment thoroughly before beginning to harvest. Clean bins or storage facilities thoroughly to remove dirt, dust and other foreign material, crop debris, chaff and grain debris.
• Clean grain going into storage to remove lightweight and broken kernels or seeds as well as foreign material and fines.
• Moisture content is by far the most important factor affecting the growth of fungi in stored grain. After harvest, grain should be dried to safe moisture contents as quickly as possible.
• Aerate grain to safe and equalized temperatures through the grain mass.
• Protect grain from insect and mite damage.
• Check stored grain on a regular basis and aerate as needed to maintain low moisture and proper temperature.

     RODENTS IN STORAGE

     Rats have been estimated to damage more than 1% of the world cereal crops and, in developing countries, estimates of 3-5% have commonly been reported. There are around 50 diseases which can be transferred to humans by rodents, including typhoid, paratyphoid, and scabies. In addition, rodents may be vectors of a large number of diseases affecting domestic animals. As rodents prefer food rich in proteins and vitamins and feed mainly on the embryo, they cause particular damage to the nutritional value and germination ability of seeds.

     The three most important rodent species are:

• Black rat or House rat (Rattus rattus)
• Norway rat or Common rat (Rattus norvegicus)
• House mouse (Mus musculus)

      There are also a number of species that are of great importance in specific regions:

• Multi-mammate rat (Mastomys natalensis) in Africa and the Middle East;
• Bandicoot rat (Bandicota bengalensis) in Southern and South East Asia;
• Pacific rat (Rattus exulans) in South East Asia, also occurring in Southern Asia

      Their teeth characterize rodents. They have a pair of incisor teeth in the upper and lower jaws. The incisors are curved inwards and have an extremely hard anterior coating. The softer inside layer is worn down much more rapidly than the hard, outer layer. This means that the teeth are continually kept sharp, enabling them to damage even materials such as masonry and electric cables. The incisors do not stop growing. This means that the animals are forced to gnaw steadily in order to wear them down. Rats and mice cause losses in a number of ways.

      1.    Feeding on stored produce

      Rats consume about 25 gm of food per day and mice eat approximately 3-4 gm per day. Besides eating stored produce, rodents contaminate a lot of the stored produce with urine, feces, hair and pathogenic agents. As it is extremely difficult to remove contamination, infested batches often have to be declared unfit for human consumption.

       2.    Damage to material and equipment (e.g. tarpaulins, bags, pallets, sprayers) and to the store itself (cables, doors). These often lead to subsequent damage:

• Produce leaking out of damaged bags or storage containers
• Bag stacks collapsing due to damage to the lower layers
• Short circuits leading to sparks or fire from cables being chewed
• Silos and warehouses may subside or even collapse as a result of being undermined
• Drainage canals around a store may be damaged.

      Signs of rodent infestation

      When there are signs of rodent infestation, it is necessary to conduct a thorough investigation of the store, its immediate surrounding area and neighboring land. There are a large number of clear signs of rodent infestation:

      Live animals: Rodents are mainly active at night. If animals are nonetheless seen during the daytime, this is a sign of an already advanced stage of infestation.

      Droppings: The shape, size and appearance of droppings can provide information as to the species of rodent and the degree of infestation. The droppings of Norway rats are around 20mm in length and are found along their runs. The droppings of Black rats are around 15mm long and are shaped like a banana. Mouse droppings are between 3 and 8mm in length and irregular in shape. Droppings are soft and shiny when fresh, becoming crumbly and matt black or gray in color after 2-3 days.

      Runs and tracks: Runs, such as those of Norway rats, are to be found along the foot of walls, fences or across rubble. They virtually never cross open areas of land, but always pass through overgrown territory, often being concealed by long grass. Runs inside buildings can be recognized by the fact that they are free of dust. The animal’s fur coming into contact with the wall leaves dark, greasy stains. Even Black rats, which do not have any fixed runs, can leave similar greasy stains at points which they pass regularly, e.g. when climbing over roof beams.

      Footprints and tail marks: Rats and mice leave footprints and tail marks in the dust. If you suspect there might be rodent infestation, scatter some sort of powder (talcum powder or flour) on the door at several places in the store and later check for traces. The size of the back feet serves as an indication of the species of rodent:

• Back feet larger than 30mm: Black rat, Norway rat, Bandicoot rat.
• Back feet smaller than 30mm: House mouse, Multi-mammate rat, and Pacific rat.

      Tell-tale damage: Rats leave relatively large fragments of grain they have nibbled at (gnaw marks). They generally only eat the embryo of maize. Sharp and small leftovers are typical for mice. Damaged sacks where grain is spilled and scattered can be a further sign of rodent attack. Small heaps of grain beneath bag stacks are a clear sign. These should be checked for using a torch on regular controls. Attention should be paid to damaged doors, cables and other material.

      Burrows and nests: Depending on their habits, rodents either build nests inside the store in corners as well as in the roof area or in burrows outside the store. Rat holes have a diameter of           between 6 and 8 cm, whereas mice holes are around 2cm in diameter. These holes can be found particularly in overgrown areas or close to the foundations of a store.

      Urine: Urine traces are fluorescent in ultraviolet light. Where available, ultraviolet lamps can be used to look for traces of urine.

      Preventive measures

      The most essential factors for the occurrence of rodents are:

• Sufficient supplies of food
• Protected places in which to build burrows and nests
• Hiding places
• Access to produce

      Good store management and preventive measures taken as part of an integrated control program can help to deal with these factors.

       Storage Hygiene and Technical Measures

• Keep the store absolutely clean! Remove any spilt grain immediately as it attracts rodents.
• Store bags in tidy stacks set up on pallets, ensuring that there is a space of 1m all round the stack.
• Store any empty or old bags and fumigation sheets on pallets, and if possible in separate stores.
• Keep the store free of rubbish in order not to provide the animals with any places to hide or nest.
• Bum or bury it.
• Keep the area surrounding the store free of tall weeds so as not to give the animals any cover! They have an aversion to crossing open spaces.
• Keep the area in the vicinity of the store free of any stagnant water and ensure that rainwater is drained away, as it can be used as source of drinking water.

      Keeping Rodents Out

     The requirements of preventive rodent control must be taken into account whenever new stores are being built. Particular attention should be paid to doors, ventilation openings, brickwork and the junctions between the roof and the walls. Repair any damage to the store immediately! This applies especially to the doors.

POST HARVEST LOSSES OF DIFFERENT COMMODITIES (FRUITS, VEGETABLES, FISH AND MEAT) IN MARKET PLACE

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:

• www.fao.org
  ochaonline.un.org
  www.apo-tokyo.org