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8. Post-harvest handling

Main points in Chapter 8


Timing harvesting to get good prices;
Harvesting at the right maturity;
Impact of bad harvesting on quality;
Harvesting at the correct time of day;
Handling in the field.


Types of packaging materials;
When to use packaging;
Types of damage that packaging protects against.


Deciding whether storage is effective or not.



This guide does not attempt to cover in depth the technical details of post-harvest handling of horticultural crops. FAO and others have covered this in many other publications.[2] The main emphasis here is on the commercial implications of different harvest and post-harvest practices. The key issues are:

The main way that you can help improve post-harvest handling is by training farmers, both through practical training and by presentations. In the following pages the main ways in which post-harvest techniques can increase farmers' profits are set out.


The timing, techniques and conditions of harvesting can significantly affect prices.

Harvesting and prices. Harvesting early in the season can be carried out to take advantage of opportunities for high prices, e.g. cabbage harvested as spring greens, young carrots sold in bunches, green plums and new potatoes. Taking advantage of these short-term market opportunities requires close links with the market.

Harvesting and crop maturity. The shelf life of the crop and its suitability for long-term storage is affected by the maturity of the crop at harvest. The optimum harvesting stage for most crops depends not only on the climate and distance to the market but also on the variety and the growing conditions. When distant markets are being investigated, experiments should be carried out to find the best maturity to harvest fruits. Send samples at different degrees of ripeness and assess which gives the best results. It may be necessary to call in expert assistance to identify whether long-term crop storage could significantly improve farmer incomes.

Harvesting and quality. Growers often do not understand the effect of their harvesting and handling on the quality of the produce when it reaches the market. Once a fruit is plucked from a plant, or a root or leaf vegetable is harvested, it is cut off from its source of food and, particularly, water. The effects of poor treatment normally show themselves some days later, when the produce is being presented for sale or is in storage. This can often result in disputes, because farmers have sent to market what they consider to be good quality products but by the time these arrive at the market the trader sees produce that has deteriorated badly. An example of this comes from Tonga, in the South Pacific, which used to export capsicum (green pepper) to New Zealand. When the fruit left Tonga they appeared to be in excellent condition but after four days in a ship they arrived in very poor condition. The problem was traced to the use of dirty knives for harvesting.

Harvest timing and marketing

The storage of root vegetables such as sweet potatoes, carrots, onions, garlic, potatoes and yams is generally improved by harvesting them when they are fully mature.

Some root crops, such as cassava and carrots, can be harvested over an extended period as they can be left in the ground.

Melons have to be harvested at the correct stage; too early and the full sugar content is not developed, too late and they lose sugar and become soft.

Some fruit, such as bananas, pineapples, mangoes and avocados, are harvested when they are not ripe in order to transport them to distant markets.

Fruits that are suitable for long-term storage, such as apples, pears, citrus and grapes, often have specific requirements as to harvesting time, depending on variety, growing region and, sometimes, the season.

Poor post-harvest handling leading to low quality produce has two effects; firstly the price is reduced and, secondly, the reputation of the production area is, over time, diminished (again tending to result in lower prices). Improved harvesting and handling of produce will result in a product with better appearance and shelf life and thus better prices.

Time of day for harvesting. Ideally, harvesting should take place when the crop and the climate are coolest and the plant has the highest moisture content. This is in the early morning but other issues have to be taken into account. For example, labour and transport may not be available early in the morning. If transport is a problem the harvest should be rescheduled to avoid produce being left standing in the field for too long. Specific crops often have ideal harvest times. For example, citrus should not be picked until the dew is dry. The best time for harvesting mangoes is mid-morning, when the latex flow is at a minimum.

Field containers. Bags or baskets attached to the waist of the picker enable both hands to remain free. The crop damage associated with moving sacks of produce through the field is thus reduced. When using bags it is preferable to be able to release the bottom so that the produce can be let out gently, rather than up-ending the bag. Containers must be emptied carefully to minimize drop heights and fruit-to-fruit damage. Containers should be cleaned as often as possible.

Harvesting techniques

Harvest fruit on high trees with a hook and a catching bag on a pole, to prevent the fruit falling to the ground and being bruised.

Harvest lettuce, cabbage, sweet pepper, egg-plant, melons and bananas using cutting tools.

should be harvested by using the palm of the hand, not by holding the fruit with the fingers.
Whenever possible, the harvesting should be carried out by plucking the stem, for example, in the case of strawberries, fine beans and peas.

Leafy vegetables...
are harvested by cutting the plant with a sharp knife as close to the root as possible.

Bulb crops...
such as garlic and onions, are harvested by pulling the leaves at the neck and then cutting the leaves about 3 cm from the bulb.

Tuber and root crops...
are normally harvested with forks or hoes.
The digging should start some 15 cm (6 inches) away from the plant. It is preferable to lever and pull the roots rather than attempt to dig them out. Harvesting is easiest when the soil is relatively dry, as both damage and the need for washing is reduced.

Using baskets or boxes with sharp or rough edges should either be avoided or the containers should be lined with paper or leaves. Damage is often caused by transferring produce from one container to another. If possible, produce should be harvested directly into the container in which it will be stored and/or transported.

Improving shelf life in the field

With highly perishable produce, damp cloths placed over the top of the field carton help give protection against the sun's heat. Some leafy vegetables may be sprinkled with water at intervals, to maintain leaf moisture.

Field containers should be removed to a shaded area as soon as possible. Shaded field-assembly points, made out of natural materials or a canvas tent, should be used in order to keep the produce cool and allow ventilation.

Drying and curing

Drying is used mainly on bulbs in order to extend shelf and storage life. Crops such as onions and garlic can be dried in the field over about six days, by being spread in a single layer. Alternatively, drying can take place under cover in stacked, shallow trays. The aim is to harden the outer scales and remove moisture from the neck of the bulb, in order to extend storage and marketing life.

Most root crops respond to warm, moist conditions after harvest by thickening and hardening their skins. This provides protection against dehydration and infection. Wound healing occurs. This is called curing and it significantly improves storage life of products like potatoes and carrots.


Grading is carried out so that:

Grading is sometimes carried out on the ground under the shade of a tree. This is both unhygienic and inefficient. Specialist grading areas or sheds are generally open-sided with tin or, preferably, thatched roofs to provide shade. Standing or sitting at tables enables people to grade quickly. Tables covered with polythene sheeting are easy to clean and the sheeting can be replaced cheaply. Lighting should be good. Tin roofs can be painted white to reflect heat, while water trickling down the outside of a shed helps reduce the heat inside the building.


Good packaging design enhances the attractiveness of produce, enables it to be handled and marketed in convenient units, and helps to prevent mechanical damage.

Mechanical damage. The four main types of mechanical damage are cuts, compression bruises, impact damage and vibration rubbing.

Packaging materials. Packaging can be the single most expensive cost, as the calculation in Table 6 showed, particularly with non-returnable containers made of wood or cardboard. The benefits of packaging must clearly justify the investment. An example of such a calculation is given in Figure 13. Traders usually aim to minimize costs and are reluctant to invest in packaging unless the financial benefits are clear.

Figure 13
A cost-benefit analysis of packaging

Assume 6 000 kg of cucumbers are produced. Market price is $0.30 per kg and packaging costs $0.05 per kg. The other marketing costs are $0.05 per kg so the net revenue is $0.20 per kg. With packaging there are no losses. Without packaging the losses vary, as does the selling price. A cost-benefit analysis needs to take into account both price differences and losses and the calculation is therefore a bit complicated.






Net revenue - packaged sales ($0.20 per kg x 6 000 kg)

1 200

1 200

1 200

1 200

Net revenue - unpackaged sales

Losses 10% Market price $0.26

1 104

Losses 10% Market price $0.27

1 158

Losses 5% Market price $0.26

1 182

Losses 5% Market price $0.27

1 242

Use packaging





Note: In calculating the impact of losses the value of the lost produce is the gross value, which includes transport costs, because these will be incurred even though the produce is wasted. The net revenue to the farmer for unpackaged sales is calculated as follows:

6 000 × (Selling price - Transport costs) - Cost of Losses
(Price × 6 000 kg × the loss expressed as decimal [i.e. 10% loss = 0.1]).
So, where losses are 10% and the market price is $0.26 then the calculation is
(6 000 × ($0.21) = $1 260 - ($0.26 × [6 000 × 0.1] = $156) = $1 104.

Five types of packaging materials are listed below.

Packaging presentation. Attractive printing and brand names can add value to fresh produce but only in markets where consumers are wealthy and appreciate aesthetics and image. In the produce markets of the Arabian Gulf and Southeast Asia multi-coloured printing is common because it helps to sell the produce and lift prices.


Produce can be stored for both short-term and long-term purposes. Short-term storage is mainly used to provide flexibility in marketing (e.g. when awaiting transport), or because buyers are not immediately available. Most horticultural crops are perishable and can only be stored for a few days. Only rarely is it worthwhile storing perishable crops to await higher prices, as storage will reduce quality and shelf life whilst adding to costs. Storage is costly and, in most instances, when the produce is withdrawn from storage it has to compete in the market against much fresher produce.

A few crops are adapted for long-term storage. These can be held in store well beyond the normal harvesting period. When they are eventually sold higher prices can usually be obtained and, by extending the marketing season, a larger volume of produce can be marketed. Often, the most successful stores are located in urban areas because:

It is rarely worth storing perishable crops to wait for higher prices.

When produce is taken out of store it has to compete with fresh fruits or vegetables.

Refrigerated storage is expensive and can only be justified if it can be run profitably. This requires an adequate demand for storage, good management and a reliable supply of electricity.

Shelf life can, however, be extended without investment in expensive storage equipment. The first priorities should be selecting high-quality produce (i.e. free of bruises, pest and disease damage), maintaining a high humidity and keeping produce in the shade.

In the right conditions, with good management, ventilated stores can be extremely cost-effective, especially for potatoes and onions. Ideally they require cool temperatures at night.

Improving farmers' returns

Emphasis has been given here to improved handling, grading and packaging. Improved prices can result from the quality of an individual consignment. In the longer term, groups of farmers can obtain premium prices by establishing an identity and a reputation as consistently high-quality suppliers by:

There are many examples of production areas that obtain premium prices because of their reputation for supplying quality produce, but it is important to remember that a reputation that takes years to establish can be quickly destroyed by one or two poor consignments.

[2] See Further Reading section at the end of this Guide.
[3] Shelf life refers to the time that a product can remain saleable.

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