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Before deciding on what packaging to use, the grower or packing-house operator has to consider many factors to ensure that the cost does not exceed the benefits. The decision should be made after consultation with market operators, packaging suppliers, transport operators and post-harvest extension advisers. Factors to consider are:
If the introduction of new packaging does not result in increased returns, it cannot be economically feasible. Most experience shows that good produce well packaged has an advantage over produce poorly packaged, and the profits from it can cover the investment. Good packaging can therefore be held to be cost-effective in marketing.
There is no assurance that new packaging will by itself eliminate or greatly reduce post-harvest losses of fresh produce. Packaging is only one factor in the effort to improve handling at every step in the marketing process.
Fresh produce sold through markets or by direct sales to users or agents must undergo some form of sorting and packaging. For the most part, the preparation of produce for market is carried out in a packing house, which may range from a simple, on-the-farm thatched shed to an automated regional packaging line handling large tonnages of a single commercial crop like citrus fruit or apples.
Whether it is simple or complex, the packing house provides a sheltered environment whose purpose is the assembly, sorting, selection and packaging of produce in an orderly manner with a minimum of delay and waste.
The size and design of the packing house, and the equipment and facilities required for it, will depend on the type and volume of produce, the market requirements, local infrastructure, its expected life span and its projected cost. In the planning stages, the factors to consider include:
Depending on the crop or crops being handled and the market being served, some or all of the following operations will be undertaken:
To be avoided at all costs is the all too common state of confusion where, in a confined space on a floor covered in plant trash, produce is being received, sorted, cleaned, dipped in fungicide, packed and stacked for dispatch (see colour section, Figure 6).
Where several producers supply the packing house, each delivery should be:
The reception area should be organized so that produce moves through the packing operation in the order it is received: first in, first out.
7.2.1 Sorting. A preliminary sorting of produce should remove unmarketable pieces and foreign matter (plant debris, soil or stones) before the produce passes on to further operations. All discarded material should be quickly hauled away from the packing house or placed in closeable bins for later removal. This is because accumulations of decaying or infested waste in or near the packing house will contaminate produce destined for market.
7.2.2 Cleaning and washing. The removal of soil and stones mentioned above can be done by hand-picking or by sieving. Some types of produce can be washed, brushed, or cleaned with a soft cloth.
Cleaning produce by hand-polishing or machine-brushing can remove light soil contamination or dust from produce, especially fruit. This should be done with care since damage to the skin of fresh produce will promote early decay.
Washing is required to clean produce which has acquired latex stains from injuries caused during harvesting, notably in mangoes and bananas. It is important to note that washing should be carried out only when absolutely essential. If it is necessary to wash produce, a fungicide should normally be applied immediately afterwards.
Use only clean, running water for washing. The washing of produce in recirculated or stagnant water should be avoided because it can quickly become heavily contaminated with decay organisms, leading to heavy rotting of the washed produce.
There are no acceptable or effective antibacterial agents available for treating water used to wash fresh produce. Hypochlorites or chlorine gas may be added to washing water used for commercial treatment of some products, but its use in recirculated or stagnant water cannot be recommended for small-scale washing operations because it is quickly inactivated by organic material such as plant debris in the water. The monitoring of the chlorine concentration in the wash water and its replenishment are difficult to achieve and, in any case, chlorine is of only limited effectiveness against decay.
Washed produce which is to be treated with fungicide should first be drained after washing in order to reduce the danger that residual wash water will dilute the fungicide below its effective concentration. When washing is not to be followed by fungicide treatment, the washed produce should be spread out in a single layer on raised racks of mesh or slats, in the shade but exposed to good ventilation to aid rapid drying (Figure 7.1).
7.2.3 Fungicide treatment. Decay caused by moulds or bacteria is a major cause of loss of fresh produce during marketing. Infection may occur before or after harvest, either through injuries or by direct penetration of the intact skin of produce. Pre-harvest infections often lie dormant until after harvest, especially in fruit, where they may develop only as the fruit ripens. Mangoes, bananas, avocados and sweet peppers are subject to latent anthracnose infections (see colour section, Figure 2).
Post-harvest application of fungicide is usual on crops such as apples, bananas and citrus fruit which are to be stored for a long period or those which undergo long periods of transport to distant markets. As stated above, fungicides are normally applied only after the produce has been washed and drained.
Most fungicides used for post-harvest decay control are in the form of wettable powders or emulsifiable concentrations. They form suspensions in water, not solutions; this means that they settle out of suspension if the mixture is not constantly agitated during its application. Thus the concentration of fungicide applied to the crop will fall below the effective level if the suspension is not continuously stirred.
In small-scale packing operations, fungicide can be applied by:
Dipping. Treatment is carried out by hand, using a suspension of fungicide agitated by hand (Figure 7.2); wire-mesh baskets can be used to dip several small pieces at one time; after dipping, produce should be drained and dried in a shaded, airy place.
Spraying. This can be accomplished with a hand-operated knapsack sprayer while produce is still in trays or racks after washing and drying produce should be sprayed completely and to the point of runoff (Figure 7.3).
Larger spraying operations may require a simple mechanized spray or drenching arrangement with a mechanical mixer for the fungicide. Produce passes through the spray or drenching in perforated trays perhaps while moving on a belt or roller conveyor (Figure 7.4).
Other methods of application, such as smokes, dusts or vapour, are used only by large-scale operations where produce is to be stored.
7.2.4 Ouality selection and size grading. Although produce will have been sorted on the farm or on its arrival at the packing house (Figure
7.5), there may be a further selection for quality and size immediately before it is packed. The scope of these operations depends on the market: will buyers be prepared to pay premium prices for quality-graded produce? Many urban customers are more demanding of quality than are rural customers.
Selection and grading in a small packing house are best done by human eye and by hand, assisted by sizing rings or gauges (Figure 7.6).
7.2.5 Waxing. The application of wax or similar coating to enhance appearance and limit water loss from produce requires specialized equipment and has little relevance to small-scale packing.
7.2.6 Packaging. Packaging in small-scale operations means the filling of marketing containers by hand (Chapter 6). Machines are used to pack durable produce like potatoes and apples in big packing houses, but they are expensive and not suitable for small volumes of different products. There are various methods of packing:
7.2.7 Special treatments after packing. Special post-packing treatments are applied to certain crops, but this is more common in large-scale operations for urban and export markets. The principal treatments are:
The treatment is to control insect pests, such as fruit fly. It is a compulsory requirement for the importation of produce into many countries and requires specialized equipment and skilled operators.
This takes several days and requires treatment of the packed fruit with ethylene gas in insulated, temperature-controlled stores. The costs are high and thus limited to large operations.
Citrus fruits grown in the tropics will remain green when ripe unless subjected to low night temperatures. They will, however, develop their normal natural colour if artificially degreened by an ethylene treatment like that initiating ripening; it is not often done in small packing houses.
7.2.8 Assembly of packed produce for dispatch. Time is an important factor in the marketing of fresh produce; delays add to losses. Once produce has been packed, it should be dispatched to market as soon as possible. Therefore the packing-house management should give high priority to transportation arrangements.
In small-scale operations, however, it may take time to assemble a full load; so when packed produce takes time to accumulate, every effort must be made to prevent its deterioration. Attention must be given to the following:
Losses of fresh produce during packing operations can be minimized if produce is:
When seeking a location for a packing house, the following must be considered:
Before the location is decided upon, the water to be used for washing produce should be checked for quality, especially if drawn from rivers, streams or standing bodies, to ensure that it is not polluted by sewage, factory effluents, pesticides, herbicides or fertilizers.
7.3.1 Site characteristics. When the general location has been chosen, the following should be observed:
Small-scale packing houses are likely to be handling a variety of crops at any one time and over a period of time. Where the volumes handled are relatively small, the layout of buildings and equipment should be simple and flexible.
7.4.1 Layout. The design will be influenced by the space available. In general, a single-level building with a receiving area at one end and a dispatching area at the other will be the most convenient arrangement. This plan separates the reception area, which will be dirty, from the packing and dispatching activities, thus reducing the risk of contamination of sorted and packed produce. It should also avoid congestion and confusion between arriving and departing vehicles (Figure 7.10). If the dimensions and shape of the site are restricted, a U-shaped layout with reception and dispatch areas beside each other is possible, but it cannot be recommended as it will certainly lead to problems of contamination and congestion, let alone problems of any future expansion.
The area of the packing house should be adequate for the easy movement of produce through three stages.
Reception. This area controls the receiving, sorting and cleaning of produce, including washing, when necessary. It is likely to be dirty with soil, dust and decaying plant material.
Ideally it should be separated (by doors, for example) from the other activities in order to limit the contamination of cleaned, sorted and packed produce.
Preparation and packing. This section will include facilities for special treatments, including drying facilities for produce washed or treated or both. The main activity will be the packing of the cleaned produce, with selection and grading facilities, if needed.
There should also be space for the storage and assembly of packing materials in dry conditions.
The whole area should be protected from the weather, but with good ventilation and lighting. The selection, grading and packing areas should be kept clean and dry.
Figure 7.10 A small-scale packing house handling a variety of produce could look like this plan
Dispatch. This activity should be located next to the packing operation but should be kept completely clear of permanent equipment. It must be large enough to provide temporary storage of packed produce and still permit unrestricted movement of workers and produce being shifted.
The dispatch area must be clean and well ventilated.
Any separate office or quality-control activity would probably be located here.
7.4.2 Construction. The building materials and type of construction will be governed by the crops to be handled, expected volume, the market to be catered for and the financing available. Small-scale operations can be successful in relatively simple and inexpensive structures. The principal requirements are:
For small-scale, on-the-farm packing, a simple structure made from cheap local materials (such as bamboo, bush poles, dried grass or other thatch) may be adequate. Such a structure may have a relatively short life, but this factor will be offset by its cost and ease of repair or replacement. If sufficient water is available, walls and roof made of dried plant materials can be periodically soaked to cool the interior of the structure.
A more durable small packing house can be built of a wooden frame with roof and walls of corrugated sheet metal over a concrete floor. In areas of strong sunlight, the heat generated in sheet-metal buildings is extreme, affecting workers and produce. If sheet metal must be used, a wide ventilation gap should be left between walls and roof, the roof itself having a wide overhang. Building walls may not be necessary if the roof is sufficiently extensive to protect produce and workers from sun and rain, and if windblown dust and rain are not problems.
Permanent packing houses should have non-slip concrete floors laid with a fall to drainage channels for easy cleaning. An antidusting surface treatment of concrete is an advantage.
Packing houses, except for those built for big commercial operations, should be free from fixed equipment installations. This allows the maximum flexibility for changing the layout as demanded by varying volumes of produce and a variety of crops.
7.4.3 Equipment. The equipment needed will be specific to each packing house, according to the scale of operations and crops handled. It will be simple and much of it can be made locally. It should be movable, and this means that concrete washing tanks should be avoided.
Figure 7.11 Polythene crates are costly but durable
When empty (a), they nest and save space in storage or transit. When filled, they stack neatly and firmly (b) if every other crate is turned in the direction opposite to that below so that crates do not nest and cannot crush contents
7.4.4 Selection, grading and packing. A final selection of produce immediately before it is packed should remove any unmarketable pieces which may have passed earlier sorting. Where small volumes of produce are dealt with by hand, a simple stand is adequate for selection, grading and packing (Figure 7.5). The stand illustrated can be made to any convenient length or duplicated if larger volumes of produce are handled.
Experienced workers can select produce and often size-grade it by eye or by simple gauges, hand-held or fixed (Figure 7.6).
Selected and graded produce is placed in the packing bin, then packed into containers placed on the shelf. Packed containers then move to the dispatch assembly area.
7.4.5 Additional equipment
Weighing. Much produce is still bought and sold by weight, so most packing houses will require some means of weighing produce. Many types of scales are made, and it is best to study the need and the types of scales available before deciding which is most suitable.
Figure 7.12 Hand-operated pallet truck can be used on level concrete floors
Figure 7.13 Wooden pallets of standard size can support several boxes or sacks of produce
Figures 7.12, 1.13 and 7.14 reproduced from Wholesale fruit and vegetable warehouses: guides for layout and design. USDA Marketing Research Report No. 467. 1966.
Washing. Washing of produce can be done in fresh running water using a galvanized tank of the kind shown in Figure 7.15. Produce that floats can be moved along the tank by water flowing from the inlet pipe, perforated on one side, across the end of the tank. The vertical baffle near the outlet end will help to ensure that all produce in the tank is properly washed.
Drying. Produce washed or treated with fungicide needs to be dried before packing. In a small packing house this can be done on a drying rack or table made of wooden slats or plastic-covered wire mesh (Figure 21). Where on-the-farm packing is done, the drying table can readily be made from bamboo or bush poles.
Where a fungicide is applied from a knapsack sprayer after washing, this can be done on the drying rack, and the produce then left to dry before packing.
Figure 7.15 Tank for washing produce can be made of galvanized sheet steel
Water entering under pressure through perforated pipe will move floating produce along tank. The baffle near drain pipe helps to circulate water through the produce
The effective management of packing houses requires a high level of efficiency in coordinating the technical, organizational and commercial aspects of operations. Errors and delays affecting any part of the operations will be reflected in growers' returns. Operations should continue throughout the year if it is economic to do so.
7.5.1 Meeting market requirements. Management should be able to advise and instruct both growers and packing-house staff in order to achieve the most efficient operations and high-quality output for the best possible returns.
7.5.2 Procurement and control. A reliable knowledge of the size and arrival times of produce crops to the packing house is essential to its efficient operation. Pickup of harvested produce may be arranged by the packing house. Growers sending produce to a central packing house should be aware of the control of quality and the standards observed. The quality of packed produce must also be controlled in order to reduce the possibility of disputes during marketing.
7.5.3 Supplies of packing materials. Estimates of the coming year's needs must be made in advance. Early arrangements should be made with suppliers to obtain the most advantageous prices and delivery dates.
Accurate stock control must be observed so that supplies do not run out during packing operations.
7.5.4 Disposal of low-grade produce. The selection and grading of produce for market will always result in some substandard pieces. They may have a certain value but should be disposed of to the best advantage of the packing house. The management must also know how much produce is a total loss. The disposal of both the low-grade produce and the total-loss produce must be accounted for.
7.5.5 Staffing. The staffing of the packing house must be adequate for its efficient operation but with attention to labour costs. This means the efficient deployment of labour and the need for adequate supervision.
Permanent staff may include a manager, clerks, mechanics and maintenance workers, drivers and some skilled packers. Peak periods will require temporary workers.
7.5.6 Staff training. The manager's responsibility for all packing-house activities requires that he be technically qualified and able to train his foremen. He must also ensure that in-service training is provided for the packing workers.
7 5.7 Grower training. When a packing house is supplied by several growers, management should ensure that they are informed as to how they can achieve the quality standards set by the market. Cooperation with post-harvest extension workers is desirable. This may include formal training out of season but will be most effective if farm visits are made when harvesting and packing-house activities are in progress.
7.5.8 Accounting and costing of operations. Agreements must be made with growers as to payments for produce, taking into account the quality control requirements. The cost of running the packing house must be estimated per kg of produce throughput to enable costs to be minimized and growers' returns maximized.
7.5.9 Documentation and accounting. The manager is responsible for seeing that accurate records are maintained and proper accounts prepared. This is fundamental to the success of the packing house as a business.
Transportation is a big and often the most important factor in the marketing of fresh produce. Ideally, transport would take produce from the grower directly to the consumer, as in many developing countries. In more complex marketing systems (those serving towns, cities or distant countries)' the cost of transport contributes significantly to the price paid by the consumer, and sometimes exceeds the value of the raw product.
Losses directly attributed to transport conditions can be high. The goal of every person concerned with transport should be that the produce be kept in the best possible condition during transport and that the haulage of produce be quick and efficient. To this end, produce should be properly packaged and properly loaded on a suitable vehicle.
The damage and loss incurred during non-refrigerated transport are caused primarily by mechanical damage and by overheating.
8.2.1 Mechanical damage. Damage of this type occurs for many reasons, including:
8.2.2 Overheating. This can occur not only from external sources but also from heat generated by the produce within the package itself.
Overheating promotes natural breakdown and decay, and increases the rate of water loss from produce.
The causes of overheating include:
