The post-harvest sector includes all the points in the value chain from production in the field to the food placed on the plate for consumption. Postharvest activities include harvesting, handling, storage, processing, packaging, transportation and marketing.
Horticultural loss is a major problem in the postharvest chain. They can be caused by a variety of factors, ranging from growth conditions to handling at the retail level. Not only are the losses obviously a waste of food, but they also represent a similar waste of human effort, agricultural input, livelihoods, investments and scarce resources like water. Post-harvest losses for horticultural products are difficult to measure. In some cases, everything harvested by farmers may end up being sold to consumers. On the other hand, the loss or waste may be considerable. Sometimes, losses may be 100%, for example when there is a fall in prices and it will be more expensive for farmers to harvest and market the product rather than plowing it back to the ground. The use of average loss figures is thus often misleading. There is a quality loss, which is measured both by the price obtained and the nutritional value, as well as the quantity.
Video Post-harvest losses (vegetables)
On-farm penyebab kehilangan
There are many factors that affect post harvest losses, from the soil in which the crop is grown for handling the product when it reaches the store. Prenatal production practices can seriously affect post-harvest results. Plants need continuous water supply for photosynthesis and transpiration. Damage can be caused by too much rain or irrigation, which can cause damage; by too little water; and by irregular water supply, which can, for example, cause growth cracks. Lack of plant foods can affect the quality of fresh produce, causing stunted growth or leaf color change, abnormal maturation and many other factors. Too much fertilizer can endanger the development and condition of post harvest yields. Good crop cultivation is important to reduce losses. Weeds compete with plants for nutrients and soil moisture. Rotting plant decay in the field is also a major loss factor.
Maps Post-harvest losses (vegetables)
Cause of loss after harvest
Fruits and vegetables are plant parts that live and contain 65 to 95 percent water. When the food and water supply runs out, it produces death and decays. Anything that increases the rate at which the food and water reserves of the product are used increases the likelihood of losses. Increased normal physiological changes can be caused by high temperature, low atmospheric humidity and physical injury. Such injuries often occur due to careless handling, causing internal bruising, rupture and rupture of the skin, resulting in rapid loss of water.
Respiration is an ongoing process at a factory and can not be stopped without harming growing plants or crops. It uses stored starch or sugar and stops when these reserves run out, causing aging. Respiration depends on good air supply. When air supply is limited to fermentation, not respiration can occur. Poor product ventilation also causes carbon dioxide accumulation. When the concentration of carbon dioxide increases then it will quickly damage the product.
Fresh produce continues to lose water after harvest. Water loss causes shrinkage and weight loss. The rate of water loss varies by product. Leafy vegetables lose water quickly because they have thin skin with many pores. Potatoes, on the other hand, have thick skin with little pores. But whatever the product, to prolong the shelf life or storage, the level of water loss should be minimal. The most significant factor is the ratio of fruit or vegetable surface area to its volume. The larger the ratio, the faster the water loss. The rate of loss is related to the difference between the vapor pressure in the product and in the air. Production results should be kept in a humid atmosphere.
Diseases caused by fungi and bacteria cause losses but viral diseases, which are common in growing plants, are not the main post-harvest problems. Deep penetration of decay makes the infected product unusable. This is often the result of infection of the harvest in the field before harvest. Loss of quality occurs when the disease only affects the surface. Leather defects can lower the selling price but do not make fruits or vegetables inedible. Fungal and bacterial diseases are spread by microscopic spores, which are distributed in the air and soil and through decaying plant material. Infection after harvest can occur anytime. Usually the harvest or handling injury.
Maturation occurs when the fruit is ripe. Maturity is followed by aging and fruit damage. The "fruit" category also refers to products such as eggplant, peppers and tomatoes. Non-climacteric fruits are only ripe while still attached to the parent plant. The quality of their meal suffered if it was harvested before it was cooked because the sugar and its acid content did not increase further. Examples are oranges, grapes and pineapples. Early felling is often done for export shipments to minimize losses during transportation, but the consequence of this is that the taste suffers. Climacteric fruit is a fruit that can be harvested when ripe but before maturation has begun. These include bananas, melons, papaya, and tomatoes. In commercial fruit marketing, maturity levels are artificially controlled, allowing for careful transport and distribution planned. Ethylene gas is produced in most plant tissues and it is important to start the maturation process. It can be used commercially for the maturation of climacteric fruits. However, natural ethylene produced by fruits can cause storage losses. For example, ethylene destroys the green color of the plant. Leafy vegetables will be damaged if stored with ripe fruit. Ethylene production increases when fruits are injured or decomposed and this can lead to early maturation of climacteric fruits during transport.
Damage in the marketing chain
Fruits and vegetables are particularly vulnerable to mechanical injuries. This can happen at any stage of the marketing chain and can result from poor harvest practices such as the use of dirty cutting knives; unsuitable containers used during harvest or during the marketing process, e.g. easily cracked containers or broken wood, sharp edges or bad spikes; overpacking or underpacking containers; and careless container handling. The resulting damage may include fruiting, deep bruising, superficial grazing, and soft product destruction. Poor handling can lead to entry of entry points for fungi and bacteria, increased water loss, and increased respiration rate.
Results can be damaged when exposed to extreme temperatures. Low temperature tolerance levels are essential when cold storage is envisioned. All products will freeze at temperatures between 0 and -2 degrees Celsius. Although some commodities are tolerant to slight freezing, poor temperature control in storage can cause significant losses.
Some fruits and vegetables are also susceptible to contaminants introduced after harvest by using contaminated field boxes; dirty water used to wash results before packing; rot, rejected products lying around packing houses; and unhealthy results pollute healthy results in the same package.
Losses directly linked to transport can be high, especially in developing countries. Damage occurs as a result of careful handling of the product packed during loading and unloading; vibration (shaking) of vehicles, especially on bad roads; and poor storage, with packets often squeezed into the vehicle to maximize revenue for the carrier. Too hot causes decay, and increases the rate of water loss. In transportation it can result from using closed vehicles without ventilation; stacking patterns that block air movement; and use vehicles that do not provide protection from the sun. Vehicle damage can be a significant cause of loss in some countries, as perishable products may be exposed to sunlight for a day or more during repair.
At a loss the stage of retail marketing can be significant, especially in poor countries. Low quality markets often provide little protection for products against the elements, leading to rapid production damage. Sorting products to separate those that can be sold from non-salable can result in a high percentage being discarded, and there is a high weight loss from leafy vegetable pruning. The arrival of fresh supplies in the market can cause existing old stocks to be thrown away, or sold for a very low price.
Avoid loss
Losses can be avoided by following good practices as mentioned above. There are also a variety of post-harvest technologies that can be adopted to increase losses during pre-harvest, harvest, cooling, temporary storage, transportation, handling and market distribution. The recommended technology varies depending on the type of loss experienced. However, all interventions must meet the principle of cost-effectiveness. In theory it should be possible to reduce losses substantially but in practice this may be very expensive. Especially for small farming, which is very important to reduce losses, it is difficult to buy expensive and intensive technology work.
Assess loss
There is no reliable method to evaluate post-harvest losses from fresh produce. Each assessment can only refer to a particular value chain on a particular occasion and, even then, it is difficult to account for quality loss or to distinguish between inevitable moisture loss and loss due to poor postharvest handling and other factors described above. Accurate loss records at different stages of the marketing chain are seldom maintained, especially in tropical countries where losses can be highest, making a reliable assessment of the cost-effectiveness of potential interventions at various stages of the chain almost impossible. Lack of such information can lead to misplaced intervention by governments and donors.
References
External links
- Washington State & amp; Extension Center, Postharvest Information Network Database
Source of the article : Wikipedia
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