The expression “post-harvest losses” means a measurable quantitative and qualitative loss in a given product. Post-harvest loss is the “degradation in both quantity and quality of a food product during the chain of interconnected activities from the time of harvest to the delivery of food to the consumer (from farm to fork or from crop to consumption).
In a hungry and increasingly competitive world, reducing postharvest food losses is a major agricultural goal. For highly perishable commodities, such as tomatoes, squash, and peaches, as much as 30 per cent of the harvested crop may be lost to postharvest diseases before it reaches the consumer. Investments made to save food after harvest is usually less costly for
A partial reduction in postharvest losses can significantly reduce the overall cost of production and lessen our dependence on marginal land and other scarce resources.
Many factors contribute to postharvest losses in fresh fruits and vegetables. These include environmental conditions such as heat or drought, mechanical damage during harvesting and handling, improper postharvest sanitation, and poor cooling and environmental control. Efforts to control these factors are often very successful in reducing the incidence of disease. For example, reducing mechanical damage during grading and packing greatly decreases the likelihood of postharvest disease because many disease-causing organisms (pathogens) must enter through wounds.
Chemicals have been widely used to reduce the incidence of postharvest disease. Although effective, many of these materials have been removed from the market in recent years because of economic, environmental, or health concerns. Increased interest in the proper postharvest handling of fresh fruits and vegetables has prompted the widespread use of flumes, water dump tanks, spray washers, and hydro coolers.
To conserve water and energy, most postharvest processes that wet the produce recirculate the water after it has passed over the produce. This re-circulated water picks up dirt, trash, and disease-causing organisms. If steps are not taken to prevent their spread, these organisms can infect all the produce that is subsequently processed. In the past, various fungicides and bactericides have been used (alone or in combination with chlorination) to prevent the transmission of diseases. These materials have often been favored over chlorination because they provide some residual protection after treatment.
At present, chlorination is one of the few chemical options available to help manage postharvest diseases. When used in connection with other proper postharvest handling practices, chlorination is effective and relatively inexpensive. It poses little threat to health or the environment.
CAUSES OF POST-HARVEST LOSSES:
Post-harvest losses are caused by both external and internal factors.
External factors which lead to postharvest losses:
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.
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.
External factors which lead to postharvest losses:
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.
Selection of varieties, according to the market requirement coupled with improved production practices, would ensure minimum wastage after harvest. For the country like Pakistan low cost, economically feasible technology such as on-farm low cost storage (structures) hydro cooling, MAP, CA storage seems to be appropriate. Sorting and grading are pre-requisite for appropriate packaging and market distribution. Low cost energy efficient on farm storage structures are to be introduced on extensive scale. Packaging has to be cost effective. Dehydration of vegetables and fruits is to be introduced as cottage industry. Preservation and processing of vegetables and fruits both at semi- commercial and commercial scale needs to be carried out. Better produce handling and management would ensure regular market supply and the consumers will enjoy the affordable prices. This will also help promoting export of high value perishable commodities to other countries. A well coordinated RandD programme on produce handling and marketing at national level is, therefore, essentially required.
The writer is associated with the Department of Agronomy University of Agriculture, Faisalabad. He can be reached at <Shakoor2914@gmail.com>
Technology Times Web team handles all matters relevant to website posting and management.