The Post-Harvest Loss of Fruits and Vegetables is a terrible blow to the economy and the lives of Sri Lankans. If the limited quantities of fruit and vegetables cultivated by the farmers in distant areas are not properly distributed islandwide, it is not only the vendors, but also the consumers who will suffer a lot. Therefore, it is important to take necessary actions to safeguard the food distribution mechanism or network covering the whole country, especially the urban areas where crops are not cultivated. Additional Director General (R&D), Industrial Technology Institute (ITI), Prof. Ilmi G. N. Hewajulige, spoke on the post-harvest loss of fruits and vegetables.
Prof. Hewajulige pointed out that the post-harvest loss of a commodity means the losses that take place from time of harvest until the produce reaches the consumer. The post-harvest loss assessment studies conducted in Sri Lanka considering the whole supply chain from farmer to consumer, indicated that the post-harvest losses of fruit and vegetables ranged between 30-40% from the harvested crop. However, such a considerable post-harvest loss of fruit and vegetables remained the same for years in conventional or traditional supply chains. The post-harvest losses in the conventional supply chains (except supermarket value chains) remained high for a long period of time even before Covid-19 pandemic situation. However, the Covid-19 pandemic and economic crisis-like incidences have directly affected the local agriculture system, production capacity, raw material sourcing and marketing. At present the limited transport facilities available due to the fuel scarcity in the country have highly affected the agriculture production and distribution throughout the country.
Post-harvest losses can be drastically reduced by adopting some technological interventions like introducing plastic crates, proper transportation and shortening the supply chain. However, the agriculture systems and its productivity are highly affected by what is happening in the country these days.
“To prevent these losses, it is important to identify where these losses occur and the causes for these losses. Every fruit and vegetable handler should understand that fruits and vegetables are alive and continue to respire even after harvest, therefore it is important to handle them with extreme care without making any damage which could affect the shelf life extension. Both quantitative and qualitative losses in variable magnitudes occur in fruit and vegetables during all pre and post-harvest stages, from harvesting, through handling, storage, processing and marketing and even to final delivery to the consumer. Inappropriate cultivation practices, improper maturity selection and harvesting and subsequent rough handling coupled with inadequate packaging, improper transport and storage are the major factors contributing for quality deterioration of perishables, causing high post-harvest losses, thereby reducing the market value as well as the market competitiveness,” said Prof. Hewajulige.
She went on to explain the exact science of this process. The quality of a fruit or vegetable cannot be improved after harvest, but can be maintained for a considerable period of time if harvested at the correct stage of maturity using proper harvesting methods and by applying suitable post-harvest management techniques. Once any fruit or vegetable detached from its mother plant, the post-harvest life depends on the rate of respiration or use of its food reserves and the consequent rate of water loss. When the food and water reserves are exhausted, the produce starts to deteriorate. Any improper post-harvest handling technique which could increase the rate of respiration makes the produce unusable. The introduction of proper post-harvest management techniques from farm to table via efficient agri-extension system is important in pre and post-harvest loss reduction and safeguarding the food security of the country.
“Sri Lanka has a long and complex marketing sequence especially in conventional or traditional supply chains of perishables with many intermediators’ involvements. These marketing chains involve the grower, collector, transport agent, wholesaler, retailer and the consumer. In some instances, fruits and vegetables are passed from one wholesale market to another within the supply chain. Such complexity of the marketing channel of perishables contributes to cumulative losses at the end by adding the losses that happened at each and every point due to miss handling. In order to gain better marketing value with reduced losses, all the actors involved in the marketing chain should actively participate together.”
Cleaning, trimming, sorting, grading and packing are important post-harvest operations to be done to maintain the quality and reduce post-harvest losses of fruit and vegetables in the supply chain. These sorting and grading practices are to be done prior to packing, especially at farm gate level to reduce losses and also to avoid the transportation of unnecessary weight to the market. However, in the present scenario, sorting and trimming like practices are mostly done at retail level, contributing to high post-harvest losses at this point. Pack house facilities established at either village level or district level are not apparent in relation to Sri Lankan conventional market chains.
There is the use of improper packaging materials such as gunny bags, poly sacks and rough wooden crates with limited ventilation facilities. But not providing any protection as a packaging is a common occurrence. Use of such unsafe packaging in fully packed open or closed transportation vehicles are proven to cause more post-harvest losses due to compression, impact and vibration damages. In the Sri Lankan situation, a considerable percentage of post-harvest loss of perishables takes place during transportation due to use of improper packaging and improper mode of transportation. The netted poly-sacks commonly used in the traditional fruit and vegetable supply chain serve as a unit of sale but do not provide protection to perishables from impact, compress and vibration shocks related damages.
“Therefore, using suitable packaging materials, either plastic, wooden or cardboard boxes with proper ventilation can preserve commodities by external damages and reduce post-harvest losses. It is important to encourage the use of plastic crates in transportation and also it is important to be aware that different products need different sizes of plastic crates depending on their perishable nature. Highly perishable, delicate commodities like tomatoes, cauliflower, broccoli and most fruits should be packed in shallow crates with proper ventilation to reduce the losses. Introducing a proper transportation system is another important aspect to be considered in reducing post-harvest loss of fruits and vegetables. Using well-ventilated vehicles with a hood/roof is suitable for transportation of perishables properly packed in crates. The netted poly sacks which are filled to more than the capacity are packed in an open lorry, with a couple of people seated on them. This creates extra stress for the perishables leading to heavy losses. It is important to consider the time of transportation from the cultivating areas to Colombo and other main markets. Night transport could provide a better environment for perishables by avoiding direct sunlight. Train compartments with proper ventilation could be effectively used as a mode of transportation of fruit and vegetables. There could be an added advantage if railway stations are located closer to packing facilities and potential markets,” explained Prof. Hewajulige.
She added that plastic crates (with ventilation facilities) are being used as a safe packaging material in most of the developed and developing countries in the world and has achieved huge success in reducing post-harvest losses by using them. The supermarket supply chains in Sri Lanka also reduced their losses up to 2-5% (compared to 30-40% losses in the traditional supply chain) by adhering to quality standards and proper pre and post-harvest management techniques including use of plastic crates and a safe mode of transportation.
“Plastic crates are considered as durable materials and can be repeatedly used for many years by adhering to the proper sanitization process after each use. The smooth inner surfaces of the crates provide a conducive environment for the commodities packed and provide a greater protection for impact, compression and vibration damages during transportation. The ventilation provided through the ventilation holes facilitate the fresh air circulation and to reduce the heat buildup within the package due to the increased rate of respiration of packaged commodities. Depending on the nature and delicacy of the commodity, the height of the crate should be selected. Since the crates are stackable, filling height is controlled and the damage caused by the compression is also minimized. It is advised to use the plastic crates even in the field to collect the harvested produce to minimize the losses at that point,” she said.
If properly cleaned, sorted and graded, and commodities are safely packed in a ventilated plastic crate and transported safely to the intended market, the damages which could happen to that commodities are minimal. Therefore, the nutritional quality of the commodities is also preserved while reducing losses.
Prof. Hewajulige concluded with some advice for our readers.
She says that we need to get ready to face the difficult times ahead. With the present food crisis, it is important to give attention to save the harvest of the limited production which is predicted, by reducing the post-harvest losses. We have to cultivate what we can in our home garden. We have to safeguard our home food security and nutrition. We can also share our harvest if we have an excess.
“We need to reduce home food loss and preserve the excess harvest using cottage level or home based food preservation techniques. We have to get ready to face the food crisis. Start food security from your home. Roughly 1/3 of the food, approximately 1.3 billion tons of food is wasted globally every year. We can start reducing food waste from our home by cooking only the adequate amount for the family. We need to educate our family members about the importance of reducing food wastage. This will help reduce home food bills.”
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