In the world near about one-third of food grown never reaches to the plates of the consumer. The degradation in both quantity and quality of food from production to consumption is known as Post Harvest loss. Quality losses mean effect of nutrient composition and the edibility of the product. These losses are generally more common in developed countries. There are a number of innovative storage technologies available, but these are yet to reach farmers, traders and government agencies involved in food storage. This project will enhance efforts to increase farmers’ access to new technologies to reduce postharvest losses. In Pakistan, the enormity of post-harvest losses of vegetables and fruits is about 35 %. Efforts are being made both at federal and provincial level to minimize the losses. However, the primary objective of research and development activities on post-harvest handling and quality preservation of vegetables and fruits is our national food security. Agro-climatic conditions of Pakistan ranging from tropical to temperate allow growing 40 different kinds of vegetables and 21 types of fruits. Major vegetables grown include potato, onion, chilli, melons, cucumber, tomato, turnip, okra and pea, whereas, citrus, dates mango, guavas, apple, banana, apricot, grapes, almonds, peach, plum and pomegranate are the main fruit crops. The area under fruits and vegetables is 0.995 million ha (4.3 per cent of the total cropped area) with the total production of 10.992 million tones. Area and production both increased in the past but at a very low stride. The major factor limiting increase in area and production remained high investment and low return to the grower. Post harvest losses in fruits and vegetables range from 25-40 %. Consumer prices rise in addition to hidden quality losses. These losses bring low return to growers, processors and traders and country suffers in terms of foreign exchange earnings.
Good Vegetables varieties
Rio Grande, Roma AVRDC Cv. (tomato), NARC 91 (onion), Medium Long Green (chilies), local selections (cucumber) and VIP (pea) have shown better transportation quality and longer shelf life. (Fruits); Begum jangi (date palm), cardinal, flame seedless (grapes), local selections (fig), sultan (pomegranate) and ARS (N) Mingora No. 7, No. 8 & No. 9 (peach) were found high yielding with longer postharvest life.
Good Fruit varieties
Deciduous Fruit Development Centre, Sariab, Quetta revealed that on rootstock MM 106, apple cultivars (red delicious, golden delicious, Star King Delicious and Spartan) showed better performance than on M-9 rootstock for fruit texture and soluble solids. Based on organoleptic evaluation or consumers’ acceptability MM-106 showed partially better performance than M9. For skin color of fruit, rootstock M9 showed better results over MM-106. However, rootstock MM-106 should better performance in terms of fruits texture, total soluble solid contents and consumers’ acceptability over M-9 rootstock.
Elements of the postharvest system (non-perishable food crops)
The time of harvesting is determined by the degree of maturity. With cereals and pulses, a distinction should be made between maturity of stalks (straw), ears or seedpods and seeds, for all that affects successive operations, particularly storage and preservation.
Pre-harvest drying (mainly for cereals and pulses)
Extended pre-harvest field drying ensures good preservation but also increases the risk of loss due to attacks by pests (birds, rodents, and insects) and moulds not to mention theft. On the other hand, harvesting before maturity entails the risk of loss through mould development leading to the decay of seeds.
Much care is needed in transporting a really mature harvest, in order to prevent detached grain from falling on the road before reaching the storage or threshing place. Collection and initial transport of the harvest thus depend on the place and conditions where it is to be stored, especially with a view to threshing.
The length of time needed for full drying of ears and grains depends considerably on weather and atmospheric conditions. In structures for lengthy drying such as cribs, or even unroofed threshing floors the harvest is exposed to wandering livestock and the depredations of birds, rodents or small ruminants. Apart from the actual wastage, the droppings left by these „marauders‟ often result in higher losses than what they actually eat. On the other hand, if grain is not dry enough, it becomes vulnerable to mould and can rot during storage.
If grain is too dry it becomes brittle and can crack after threshing, during hulling or milling, especially for rice if milling takes place longer time 2-3 months after the grain has matured, thus causing heavy losses. During winnowing, broken grain can be removed with the husks and is also more susceptible to certain insects e.g. flour beetles and weevils. Lastly, if grain is too dry, this means a loss of weight and hence a loss of money at the time of sale.
If a harvest is threshed before it is dry enough, this operation will most probably be incomplete. If grain is threshed when it is too damp and then immediately heaped up or stored (in a granary or bags), it will be much more susceptible to attack by microorganisms, thus limiting its conservation.
Storage is the art of keeping the quality of agricultural materials and preventing them from deterioration for specific period of time, beyond their normal shelf life. Different crops are harvested and stored by various means depending on the end utilization. Whether the seed will be used for new plantings the following year, for forage being processed into livestock feed, or even for crops to be developed for a special use, the grower must be aware of harvesting and storage requirements toward a quality product. After determining the prescribed use for the crop, timing for harvest and storage is of important consideration. Along with an assessment of when to harvest, the farmer needs to determine the method of harvesting.
There are a wide range of storage structures used throughout the world to successfully store horticultural produce. In general the structure needs to be kept cool (refrigerated, or at least ventilated and shaded) and the produce put into storage must be of high initial quality.
Essential of storage
- Perishable nature of agric. & biomaterials
- Provision of food materials all year round
- Pilling/ provision for large scale processing
- Preservation of nutritional quality
- Price control and regulation
- Optimization of farmers‟ gain / financial empowerment of farmers
- Opportunity for export market, etc.
Excessive threshing can also result in grain losses, particularly in the case of rice (hulling) which can suffer cracks and lesions. The grain is then not only worthless, but also becomes vulnerable to insects such as the rice moth (Corcyra cephalonica).
Marketing is the final and decisive element in the postharvest system, although it can occur at various points in the agro-food chain, particularly at some stage in processing. Moreover, it cannot be separated from transport, which is an essential link in the system.
Sohaib Safar Khan, Muhammad Yahya, Arshad Abbas, Amir Aziz, Abid Kamran, Adeel Ahmad
University college of Agriculture, University of Sargodha