After harvest, fruits and vegetables need to be prepared for sale. This can be undertaken on the farm or at the level of retail, wholesale or supermarket chain. Regardless of the destination, preparation for the fresh market comprises four basic key operations:
1. Removal of unmarketable material,
2. Sorting by maturity and/or size,
3. Grading,
4. Packaging.
Any working arrangement that reduces handling will lead to lower costs and will assist in reducing quality losses. Market preparation is therefore preferably carried out in the field. However, this is only really possible with tender or perishable products or small volumes for nearby markets. Products need to be transported to a packinghouse or packing shed in the following cases: for large operations, distant or demanding markets or products requiring special operations like washing, brushing, waxing, controlled ripening, refrigeration, storage or any specific type of treatment or packaging.
These two systems (field vs. packinghouse preparation) are not mutually exclusive. In many cases part field preparation is completed later in the packing shed. Because it is a waste of time and money to handle unmarketable units, primary selection of fruits and vegetables is always carried out in the field. In this way products with severe defects, injuries or diseases are removed.
Lettuce is an example of field preparation where a team of three workers cut, prepare and pack (Figure 22). For distant markets, boxes prepared in the field are delivered to packhouses for palletizing, precooling, and sometimes cold storage before shipping. Mobile packing sheds provide an alternative for handling large volumes in limited time. Harvest crews feed a mobile grading and packing line (Figure 23). On completion of loading, the consignment is shipped to the destination market and replaced by an empty truck. In mechanized harvesting, the product is transported to the packhouse (Figure 24) where it is prepared for the market. In many cases, harvest crews make use of an inspection line for primary selection on the field.
Figure 22: Lettuce field preparation for the fresh market.
Figura 23: Mobile packing shed for market preparation of celery.
Figure 24: Mechanized harvest of tomato.
A packinghouse allows special operations to be performed. Another advantage (over field preparation) is that products can be prepared continuously for 24 hours regardless of the weather. With its capacity to process large volumes, farmers associations, cooperatives, or even community organizations can take advantage of these opportunities.
The size and degree of complexity of a packing shed depends on the following factors: crop(s) and volume to be processed, capital to be invested, its objectives such as handling of owner's production or to provide service to others. Packing sheds range from a straw shelter to highly automated facilities. In some cases storage rooms as well as offices for commercial sales are annexed to packing sheds.
A packhouse can be defined as a place protected from weather for both, product and personnel. It is organized in such a way that product is prepared in a centralized handling operation. To some extent, this is similar to a factory assembly line, where raw material from the field undergoes a sequence of activities resulting in the final packaged product.
A packinghouse needs to be located close to the production area and within easy access to main roads or highways. It also needs to have one entrance to facilitate and control supply and delivery. Moreover, it needs to be large enough for future expansion or additional new facilities. Sufficient space outside is also required to avoid congestion of vehicles entering and leaving. Buildings should be designed to ensure sufficient shade during most of the day in the loading and unloading areas. They also need good ventilation in summer and protection in winter.
Packinghouses are usually built with cheap materials. However, it is important to create a comfortable environment both for produce and workers. This is because product exposed to unfavorable conditions can lead to rapid deterioration in quality. Also, uncomfortable working conditions for staff can lead to unnecessary rough handling.
A packinghouse should have adequate room for easy circulation with ramps to facilitate loading and unloading. Doors and spaces should be sufficiently large to allow the use of forklifts.The reception area should be large enough to hold product equivalent to one working day. The main reason for this is to keep the packinghouse in operation in the event of an interruption in the flow of product from the field (rain, machine breakdown, etc).
Electricity is critical for equipment, refrigeration and particularly lighting. Because packhouses usually work extended hours or even continuously during harvest time, lighting (both, intensity and quality) is critical in identifying defects on inspection tables. Lights should be below eye level to prevent glare and eyestrain (Figure 25). Light intensity should be around 2 000-2 500 lx for light coloured products but 4 000-5 000 for darker ones. The working area together with the whole building should have lighting. This is in order to avoid the contrasts caused by shaded areas, resulting in temporary blindness when the eyes are raised. Dull colours and non-glossy surfaces are a requirement for equipment, conveyor belts and outfits. In this way, defects are not masked because of the reflection of light. It also helps to reduce eye fatigue.
A good supply of water is important for washing product, trucks, bins and equipment, as well as for dumping. In some cases it may also be necessary for hydro cooling. Provision of an adequate waste water disposal system is as important as a good source.
Administration offices should be located on clean and quiet areas and if possible elevated. This is so that the entire operation is visible. (Figure 26). Packinghouses should have facilities or laboratories for quality analysis.
After working out the details of the building layout, it is important to prepare a diagram for the movement of product throughout the packinghouse and activities to be undertaken for the entire operations. Handling must be minimized and movement of product should always be in one direction without crossovers. It may be possible to undertake operations concurrently, such as working simultaneously on different sizes or maturity stages.
2.2.2.1 Reception
Preparation and packing operations should be designed to minimize the time between harvest and delivery of the packaged product. Reception is one area where delays frequently occur (Figure 27) and the product should be protected from the sun as much as possible. Product is normally weighed or counted before entering the plant and in some cases samples for quality analysis are taken (Figure 28). Records should be kept, particularly when providing a service to other producers.
Preparation for the fresh market starts with dumping onto packinghouse feeding lines. Dumping may be dry (Figure 29) or in water (Figure 30). In both cases it is important to have drop decelerators to minimize injury as well as control the flow of product. Water dipping produces less bruising and can be used to move free-floating fruits. However, not all products tolerate wetting. A product with a specific density lower than water will float, but with other products salts (sodium sulfate, for example) are diluted in the water to improve floatation.
Figure 25: Lighting at eye level causes blinding and eye fatigue. Lighting fixtures should also be covered to prevent glass shattering over produce if broken.
Water dipping through washing helps to remove most dirt from the field. For thorough cleaning, more washings and brushing are required. Water rinsing allows produce to maintain cleanliness and be free of soil, pesticides, plant debris and rotting parts. However, in some cases this is not possible. This is because of insufficient water. If recirculated water is used, this needs to be filtered and settled dirt removed.
Figure 26: Elevated administration offices allow process supervision.
Chlorination of dumping and washing waters with a concentration 50-200 ppm of active chlorine, eliminates fungi spores and bacteria on the surface of diseased fruits. This prevents the contamination of healthy fruit. In addition to this, bruising should be avoided since this is the entry for infection by decay organisms. At depths greater than 30 cm and for periods of time longer than 3 minutes, water tends to penetrate inside fruits, particularly those that are hollow such as peppers. Water temperature also contributes to infiltration. It is recommended that fruit temperature is at least 5 °C lower than liquid.
Figure 27: Delays should be avoided either at reception or delivery, particularly when produce is exposed to the sun.
2.2.2.2 Removal of rejects
After dumping, the first operation that usually follows is the removal of unmarketable material. This is because handling of plant material that cannot be sold is costly. This is performed prior to sizing and grading. Primary selection is one of the four basic operations for market preparation carried out in the field. This step involves the removal of over mature, too small, severely damaged, deformed or rotting units.
Very small produce is usually mechanically removed by mesh screens, pre-sizing belts or chains. Bruised, rotted, off-shaped units, wilted or yellow leaves are usually removed by hand. Garlic and onions are topped to remove the dry foliage attached to the bulbs by specific equipment (Figure 31) and in many crops soil and loose parts are removed by brushing (Figure 32). In crops where water dipping is possible, differential floatation could be used to separate rejects. In addition to this, detergents and brushes can be used to remove soil, latex, insects, pesticides etc. Clean fruits should be dried with sponges or hot air.
Culls as well as other plant parts from cutting, peeling, trimming, bruised and spoiled fruits can be used for animal feeding. Although they provide a good source of energy and are extremely tasty, their high water content makes them bulky and expensive to transport. In addition to this, their nutritional value is less than other food sources. This is because of their low protein and dry matter contents (in terms of volume). Their inclusion in the diet must be in the right proportions to avoid digestive problems. Another disadvantage is that in many cases they are highly perishable and cannot be stored. This means that they cannot be gradually introduced into the animal's diet. When not used for animal feeding, they can be disposed as sanitary fillings or organic soil amendments.
Figure 28: Sampling for quality before grading.
2.2.2.3 Sizing
Sizing is another basic operation undertaken in a packhouse and can be carried out before or after sorting by colour. Both operations should always be carried out before grading. This is because it is easier to identify units with defects on a uniform product, either in terms of size or colour.
There are two basic systems - according to weight or dimensions (diameter, length or both). Spherical or almost spherical products like grapefruits, oranges, onions, and others, are probably the easiest to sort by size. Several mechanisms are available from mesh screens to diverging belts (Figure 33) or rollers with increased spaces between them (Figure 34). Sizing can also be performed manually using rings of known diameter (Figure 35). Sorting by weight is carried out in many crops with weight sensitive trays. These automatically move fruit onto another belt aggregating all units of the same mass (Figure 36).
Figure 29: Dry dumping of lemons (Photograph: P. A. Gómez, INTA E.E.A. Balcarce).
2.2.2.4 Grading
Amongst the four basic operations, this is probably the most important. It consists of sorting product in grades or categories of quality. Two main systems exist: static and dynamic. Static systems are common in tender and/or high value crops. Here the product is placed on an inspection table where sorters remove units which do not meet the requirements for the grade or quality category (Figure 37). The dynamic system is probably much more common. Here product moves along a belt in front of the sorters who remove units with defects (Figure 38). Main flow is the highest quality grade. Often second and third grade quality units are removed and placed onto other belts. It is much more efficient in terms of volume sorted per unit of time. However, personnel should be well trained. This is because every unit remains only a few seconds in the worker's area of vision. There are two types of common mistakes: removing good quality units from the main flow and more frequently, not removing produce of doubtful quality.
Rejects mainly on aesthetic grounds provide a second or even third quality grade. These can be marketed in less demanding outlets or used as raw material for processing.
Figure 30: Water dumping of apples.
Small scale processing, however, needs to be able to achieve a standard of quality similar or even better than large industries. This is not always possible because industrial plants tend to use specific varieties and processes. In addition to this, surpluses for the fresh market and sub-standard products do not provide uniform raw material. The industrial yield is low and this together with the low technology in the manufacturing process can result in a product of variable quality. At this point, it is important to highlight that the quality of a processed product will depend both upon, the quality of the raw material and the manufacturing process.
These operations are commodity specific. They are different from basic operations because they are carried out on every crop independent of size and sophistication of the packinghouse.
2.2.3.1 Colour sorting
These are common in fruits and fruit vegetables and can be undertaken electronically. Fruits are usually harvested within a range of maturity (Figure 39) that needs to be uniform for sale. Harvesting within a narrow range of maturity reduces colour sorting. However, this is only possible for low-volume operations.
Figure 31: Topping onions before grading.
2.2.3.2 Waxing
Some fruits such as apples, cucumbers, citrus, peaches, nectarines and others, are waxed for the following reasons: to reduce dehydration, improve their postharvest life by replacing the natural waxes removed by washing and to seal small wounds produced during handling. Waxes are also used as carriers of some fungicides or just to increase shine and improve appearance. Different types and formulae of waxes are available.
These can be applied as sprays or foams, or by immersion and dripping or in other ways. Uniform distribution is important. Soft brushes, rollers or other methods are used to ensure that application on the surface of fruit is thorough and texture is even. Heavy application can block fruit gas exchange and produce tissue asphyxia. Internal darkening and development of off-flavors and off-odors are some of the characteristics. It is very important that waxes are approved for human consumption.
2.2.3.3 Degreening
The main causes of greening are climatic conditions before harvest. For example, citrus often reaches commercial maturity with traces of green colour on the epidermis (flavedo). Although not different from fruits with colour, consumers sense that they are not ripe enough and have not reached their full flavor. Degreening consists of chlorophyll degradation to allow the expression of natural pigments masked by the green colour. In purpose built chambers, citrus fruits are exposed from 24 to 72 hours (depending on degree of greening) to an atmosphere containing ethylene (5-10 ppm) under controlled ventilation and high relative humidity (90-95%). Conditions for degreening are specific to the production area. Artés Calero (2000) recommends temperatures of 25-26 °C for oranges, 22-24 °C for grapefruit and lemon and 20-23 °C for mandarins.
Figure 32: Brushing and hand removal of damaged fruits before grading. (Photograph: S. Horvitz, INTA E.E.A. Balcarce).
Figure 33: Sizing onion bulbs by diverging belts. The different speed of belts makes bulbs rotate besides moving forward to a point where bulb diameter equals belt separation.
Figure 34: Sizing with rollers of increasing distance between them.
Figure 35: Sizing with rings of known diameters (Photograph: P. A. Gómez, INTA E.E.A. Balcarce).
Figure 36: Sizing by weight. Individual trays deposit fruit on the corresponding conveyor belt.
Figure 37: Static quality grading system. Product is dumped onto an inspection table where defective units are removed.
2.2.3.4 Controlled ripening
Maturity at harvest is the key factor for quality and postharvest life. When shipped to distant markets, fruits need to be harvested slightly immature (particularly climacteric ones) to reduce bruising and losses during transport. Prior to distribution and retail sales, however, it is necessary to speed up and achieve uniform ripening. The main reason for this is so that product reaches consumers at the right stage of maturity. As with degreening, ethylene is used but at higher concentrations. Banana provides a typical example of this type of operation. It can however, also be carried out on tomatoes, melons, avocados, mangoes and other fruits (Table 3).
Controlled ripening is performed in purpose built rooms where temperature and relative humidity can be controlled and ethylene removed when the process has been completed. The process involves initial heating to reach the desired pulp temperature. This is followed by an injection of ethylene at the desired concentration. Under these conditions, the product is maintained for a certain amount of time followed by ventilation in order to remove accumulated gases. On completion of the treatment, the temperature is reduced to the desired level for transportation and/or storage. Ethylene concentration and exposure time are a function of temperature, which accelerates the process.
Table 3: Conditions for controlled ripening of some fruits.
| |
Ethylene concentration (ppm) |
Ripening temperature °C |
Exposure time to these conditions (hr.) |
|
Avocado |
10-100 |
15-18 |
12-48 |
|
Banana |
100-150 |
15-18 |
24 |
|
Honeydew melon |
100-150 |
20-25 |
18-24 |
|
Kiwifruit |
10-100 |
0-20 |
12-24 |
|
Mango |
100-150 |
20-22 |
12-24 |
|
Stone fruits |
10-100 |
13-25 |
12-72 |
|
Tomato |
100-150 |
20-25 |
24-48 |
Adapted from Thompson, 1998.
Figure 38: Dynamic quality grading system. Sized onion bulbs continuously flow on inspection tables where defective products are removed. Final inspection is performed before bagging (right hand side).
Figure 39: Fruits are harvested within a range of maturity and they should be separated by colours before packing. (Photograph: S. Horvitz, INTA E.E.A. Balcarce).
2.2.3.5 Pest and disease control
Different treatments are performed to prevent and control pests and diseases at postharvest level. Fungicides belonging to different chemical groups are widely used in citrus, apples, bananas, stone fruits and other fruits. Most have a fungistatic activity. This means that they inhibit or reduce germination of spores without complete suppression of the disease. Chlorine and sulfur dioxide are amongst those most widely used.
Chlorine is probably the most widely used sanitizer. It is used in concentrations from 50 to 200 ppm in water to reduce the number of microorganisms present on the surface of the fruit. However, it does not stop the growth of a pathogen already established. Table grapes are usually fumigated with sulfur dioxide to control postharvest diseases at a concentration of 0,5% for 20 minutes followed by ventilation. During storage, periodic (every 7-10 days) fumigations are performed in concentrations of 0.25%. During transport, pads impregnated with sodium metabisulfite can be used inside packages. These slowly generate sulfur dioxide in contact with the humidity released by fruits.
Gas fumigation is the most important method for eliminating insects, either adults, eggs, larvae or pupae. Methyl bromide was probably the most widely used fumigant for many years but it is banned in most countries. It has been replaced by temperature (high and low) treatments, controlled atmospheres, other fumigants or irradiation.
It is also possible to prevent some postharvest physiological disorders with chemical treatments. For example, calcium chloride (4-6%) dips or sprays for bitter pit in apples. Other methods include dipping or drenching fruits in chemical solutions to avoid storage scalds or other disorders. Similarly, the addition of low concentrations of 2.4-D to waxes assists in keeping citrus peduncles green.
2.2.3.6 Temperature treatments
Cold can be used in low temperature tolerant fruits (apples, pears, kiwifruit, table grapes, etc.) and other potential carriers of quarantine pests and/or their ovipositions. Exposure to any of the following combinations of temperatures and time is provided in the following recommendations (Table 4).
Heat treatments like hot water dips or exposure to hot air or vapor have been known for many years for insect control (and for fungi, in some cases). When restrictions were extended to bromine based fumigants, however, heat treatments were reconsidered as quarantine treatments in fruits such as mango, papaya, citrus, bananas, carambola and vegetables like pepper, eggplant, tomato, cucumber and zucchinis. Temperature, exposure and application methods are commodity specific and must be carried out precisely in order to avoid heat injuries, particularly in highly perishable crops. On completion of treatment, it is important to reduce temperature to recommended levels for storage and/or transport.
Hot water immersion requires that fruit pulp temperature is between 43 and 46,7 °C for 35 to 90 minutes. This depends on commodity, insect to be controlled and its degree of development (U.S. E.P.A., 1996). Dipping in hot water also contributes to reduced microbial load in plums, peaches, papaya, cantaloupes, sweet potato and tomato (Kitinoja and Kader, 1996) but does not always guarantee good insect control (U.S. E.P.A., 1996). For the export of mangoes from Brazil, it is recommended that dipping is performed at 12 cm depth in water at 46,1 °C and for 70-90 minutes (Gorgatti Neto, et al., 1994).
Table 4: Combinations of temperature and exposure time for fruit fly quarantine treatments.
|
Time (days) |
Maximun temperature (°C) |
|
|
Ceratitis capitata |
Anastrepha fraterculus |
|
|
10 |
0,0 |
|
|
11 |
0,6 |
0,0 |
|
12 |
1.1 |
|
|
13 |
|
0,6 |
|
14 |
1,7 |
|
|
15 |
|
1,1 |
|
16 |
2,2 |
|
|
17 |
|
1,7 |
Adapted from Gorgatti Netto, et al., 1993.
Many tropical crops are exposed to hot and humid air (40-50 °C up to 8 hours) or water vapor to reach a pulp temperature which is lethal to insects. Hot air is well tolerated by mango, grapefruit, Navel oranges, carambola, persimmon and papaya. Similarly, vapor treatments have been approved by the USDA-APHIS (U.S. Department of Agriculture, Animal and Plant Health Inspection Service) for clementines, grapefruits, oranges, mango, pepper, eggplant, papaya, pineapple, tomatoes and zucchinis (U.S. E.P.A., 1996).
2.2.3.7 Sprout suppression
In potatoes, garlic, onion and other crops, sprouting and root formation accelerate deterioration. They also determine the marketability of these products. This is because consumers strongly reject sprouting or rooting products.
After development, bulbs, tubers and some root crops enter into a "rest" period. This is characterized by reduced physiological activity with non response to environmental conditions. In other words, they do not sprout even when they are placed under ideal conditions of temperature and humidity. Different studies show that during rest, endogenous sprout inhibitors like abscisic acid predominate over promoters like gibberellins, auxins and others. This balance changes with the length of storage to get into a "dormant" period. They will then sprout or form roots if placed under favorable environmental conditions. There are no clear-cut boundaries between these stages. Instead, there is a slow transition from one to the other as the balance between promoters and inhibitors change. With longer storage times, promoters predominate and sprouting takes place.
Refrigeration and controlled atmospheres reduce sprouting and rooting rates but because of their costs, chemical inhibition is preferred. In onions and garlic Maleic Hydrazide is sprayed before harvest while in potatoes CIPC (3-chloroisopropyl-Nphenylcarbamate) is applied prior to storage as dust, immersion, vapor or other forms of application. As CIPC interferes with periderm formation, it must be applied after curing is completed.
2.2.3.8 Gas treatments before storage
Different studies have shown that exposure to carbon dioxide rich atmosphere (10-40% up to week) before storage, contributes towards maintaining quality in grapefruits, clementines, avocados, nectarines, peaches, broccoli and berries (Artes Calero, 2000). Control of insects is possible with higher concentrations (60-100%). The effect of this gas is not well understood. What is known is that it has an inhibitory effect on metabolism and ethylene action and the effect is persistent after treatment. Also, at higher concentrations (> 20%) there is difficulty in spore germination and growing of decay organisms.
Similarly, exposure to very low oxygen atmosphere (< 1%) also contributes towards preserving quality and controlling insects in oranges, nectarines, papaya, apples, sweet potatoes, cherries and peaches (Artés Calero, 2000). Lowering oxygen concentration reduces respiratory rate and the whole metabolism.
The main purpose of packaging is to ensure that the product is inside a container along with packing materials to prevent movement and to cushion the produce (plastic or moulded pulp trays, inserts, cushioning pads, etc.) and for protection (plastic films, waxed liners, etc.). It needs to satisfy three basic objectives. These are to:
A well-designed package needs to be adapted to the conditions or specific treatments required to be undertaken on the product. For example, if hydrocooling or ice-cooling need to be undertaken, it needs to be able to tolerate wetting without losing strength; if product has a high respiratory rate, the packaging should have sufficiently large openings to allow good gas exchange; if produce dehydrates easily, the packaging should provide a good barrier against water loss, etc. Semi-permeable materials make it possible for special atmospheres inside packages to be generated. This assists in maintaining produce freshness.
2.2.4.1 Categories of packaging
There are three types of packaging:
1. Consumer units or prepackaging
2. Transport packaging
3. Unit load packaging or pallets
When weighed product reaches the consumer in the same type of container in which it is prepared - this is described as a consumer unit or prepackaging. Normally, this contains the quantity a family consumes during a certain period of time (300 g to 1,5 Kg, depending of product). Materials normally used include moulded pulp or expanded polystyrene trays wrapped in shrinkable plastic films (Figure 40), plastic or paper bags, clamshells, thermoformed PVC trays, etc. Onions, potatoes, sweet potatoes etc are marketed in mesh bags of 3-5 Kg. Colours, shapes and textures of packaging materials play a role in improving appearance and attractiveness.
Transport or packaging for marketing usually consists of fiberboard or wooden boxes weighing from 5 to 20 Kg or bags can be even heavier (Figure 41). They need to satisfy the following requirements: be easy to handle, stackable by one person; have the appropriate dimensions so that they fit into transport vehicles and materials should be constructed with biodegradable, non-contaminating and recyclable materials. Packaging intended for repeated use should be: easy to clean and dismantle so that it is possible to significantly reduce volume on the return trip; ability to withstand the weight and handling conditions they were designed for (Figure 42), and meet the weight specifications or count without overfilling (Figure 43).
In these type of packages it is common to use packaging materials which serve as dividers and immobilize the fruit. For example, vertical inserts can be used. They also assist in reinforcing the strength of the container, particularly when large or heavy units such as melons or watermelons are packed. Trays also have the same objective but they separate produce in layers. They are common in apples, peaches, plums, nectarines, etc. Plastic foam nets are used for the individual protection of large fruits like watermelons (Figure 44), mango, papayas, etc. It is also possible to use paper or wood wool, papers or other loose-fill materials.
Figure 40: Consumer packaging or prepackaging.
In many developing countries containers made of natural fiber are still used for the packaging of fruits and vegetables (Figure 45). Although cheap, they cannot be cleaned or disinfected. They therefore represent a source of contamination of microorganisms when reused. Moreover, there is a risk of bruising as a result of compression. This is because they were not designed for stacking. In addition to this, the significant variations in weight and/volume makes marketing a complex business.
Finally, pallets have become the main unit load of packaging at both domestic and international level. Their dimensions correspond to those of maritime containers, trucks, forklifts, storage facilities, etc. As unit loads they reduce handling in all the steps in the distribution chain. Different sizes exist. However, the most common size internationally is 120 x 100 cm. It is sometimes made of plastic materials. Depending on the packaging dimensions, a pallet may hold from 20 to 100 units. To ensure stability, pallet loads are secured with wide mesh plastic tension netting (Figure 46) or a combination of corner post protectors and horizontal and vertical plastic strapping (Figure 47). In many cases individual packages are glued to each other with low tensile strength glue that allow separate units but prevent sliding. They are also stacked crosswise or interlocked to contribute to the load stability.
Figure 41: Different packaging containers for fruits and vegetables.
Figure 42: Weak containers or inadequate stacking patterns may collapse producing compression damages
There is a trend towards standardization of sizes. This is because of the wide variety of shapes and sizes of packaging for fruits and vegetables,. The main purpose of standardization is to maximize utilization of the pallet's surface based on the standard size 120 x 100 cm. The ISO (International Standards Organization) module (norm ISO 3394) sets 60 and 40 cm as basic horizontal dimensions divided in subunits of 40 x 30 cm and 30 x 20 cm (Figure 48). There are no regulations regarding the height of individual packages. However, the palletized load should not exceed 2.05 m to ensure safe handling. On the recommendation of USDA, the MUM system (Modularization, Unitization and Metrication) also has as its objective, container standardization on the basis of the 120 x 100 cm pallet.
Figure 43: Overfilling containers is the main reason for compression damages.
Figure 44: Individual protection of large fruits.
Figure 45: Natural fibre containers for vegetables.
Figure 46: Pallet stabilization with mesh plastic tension netting.
Figure 47: Pallet stabilization with corner posts and strapping.
The trend towards the use of non-returnable containers poses an environmental challenge. To reduce the impact, packages need to be designed to meet their functional objectives, with minimal wastage of materials and need to be recyclable, after their main functional use.
Figure 48: Different horizontal package dimensions to maximize utilization of a 100 x 120 cm pallet, according to MUM and ISO (shaded) systems.
