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Preventing post-harvest losses key to food security

FROM the huge quantities of the produce that go to waste after harvest, it is evident that post-harvest loss (PHL) is one factor that is not planned for by many farmers.
PHLs are so visible at Lusaka’s Soweto Market and many other markets across the country which are trading places for agricultural produce.
This is why the need for farmers who undertake agricultural activities to critically look at preventing PHL cannot be overemphasised.
It is worth noting that PHL happens at every stage of the supply chain such as harvesting, drying and storage.
These are all stages which see substantial losses, both quantitative (physical losses caused by rodents, insects or infestations) and qualitative (loss of quality and value).
According to an online publication, ‘The Guardian’, in sub-Saharan Africa alone the value of PHL is about US$4 billion a year.
The extent of these losses is substantial but measuring them can be difficult but estimates range from five to 30 percent or more. This represents a vast amount of food, along with the wasted cost and effort of producing it.
In Zambia and world over, fruits, vegetables and maize are the most perishable agricultural produce. Food is wasted throughout the supply chain, from initial agricultural production down to final household consumption.
Maize is not only Zambia’s staple food but provides income to farmers. It has also been hit by uncertainties and in cases where yield is good, wastage still occurs.
According to the International Maize and Wheat Improvement Center, one of the key constraints to improving food and nutritional security in Africa is the poor post-harvest management that leads to between 14 percent and 36 percent loss of maize grain, thereby aggravating hunger.
PHL contributes to high food prices because it removes part of the supply from the market. Reducing PHL in maize is an essential component in any strategy to make more food available and reducing the cost of mealie meal and other maize products. Solving the post-harvest management problems in maize will require cooperation and effective linkage among the following: research, extension, agro-industry, marketing system and favourable policy environment.
Losses of maize can be minimised by physically avoiding the entry of insects and rodents, and maintaining the environmental conditions that avoid growth of micro-organisms. The knowledge of control points during harvesting and drying before storage can help in reducing losses during the storage.
It is worth noting that a major portion of food is wasted due to quality standards among other factors, such as careless handling during harvesting, packing, transportation and storage.
Environmental factors such as temperature and humidity also lead to PHL.
Inadequate storage facilities at the producing or marketing centres also cause PHL.
Longer distribution period also causes losses.
It is clear that populations are growing, so is the need for more food. This is why the need to prevent PHL cannot be overemphasised.
Fortunately, it is possible to reduce PHL.
It can be minimised by proper harvesting, transportation, storage, pre- and post- harvest treatments.
Therefore, it is important that harvesting should not be delayed if PHLs are to be avoided. Almost all the crops are badly affected due to delayed harvesting. For example, over-maturity in root crops causes sponginess. There is need to make sure that a crop is harvested at the appropriate stage, and the pickers are trained on evaluating maturity. For fruits and vegetables, harvesting should be done during cooler times of the day and the produce should be shifted to the packing shade as early as possible.
Heavy irrigation on matured crops should be avoided because it results in cracking of fruits and vegetables.
Packaging of fresh fruits and vegetables has a great significance in reducing wastage. Packaging also provides protection from damage. Cheap packaging technique and materials such as polythene films, paper board boxes lined with polyethylene and other materials can effectively prolong the storage life of fruits and vegetables. Vegetables can be protected from the influence of dry air by packing in various types of plastic films.
Vegetables such as okra which deteriorate fast need prompt cooling and their storage losses can be reduced by pre-cooling. Cooling is equally useful in case of fruits. It reduces their respiration rate, especially climatic fruits such as banana, papaya and mango, thereby preventing over-ripening.
Quick transport of fruits and vegetable in order to maintain the quality with minimum damage during transportation is very important. The losses in transportation occur due to physical and mechanical injury and uncontrolled conditions, mainly temperature and humidity.
It is important that horticultural produce reaches the market as soon as possible and at a time when the market needs it the most.
A perfect and efficient marketing system is essential to avoid losses of fruits and vegetables.
Avoiding injury on the fruits is essential. When you have cuts or cracks in the fruit, it creates entry points for micro-organisms. To avoid this, make sure that knives are sharp, and the pickers are trained properly. The knives must not only be sharp, but they should be clean.
When transporting the produce from the field to the packinghouse, make sure the truck is not overloaded because the fruits at the bottom can get compressed. The loaders should not toss or throw produce onto the truck. This will help avoid bruising.
It is an undoubtable fact that eliminating PHL is possible and doing so increases food availability and reduces food prices, thereby reducing poverty and contributing to the nation’s food security.
The author is a photojournalist and writer.