Post harvest handling of fruits and vegetables by Prof. Ganesh Shinde 

Post harvest handling of fruits and vegetables by Prof. Ganesh Shinde
POST HARVEST HANDLING
 Being living organs, fruits and vegetables continue to respire even after harvesting when they have a limited source of food reserves.
 In addition to degradation of respiratory substrates, a number of changes in taste, colour, flavour, texture and appearance take place in the harvested commodities which make them unacceptable for consumption by the consumers if these are not handled properly.
 Post-harvest technology starts immediately after the harvest of fruits and vegetables.
 The whole process of processing the commodities is categorized as Handling of fresh produce.
 Post-harvest Technology of fresh fruits and vegetables combines the Biological and environmental factors in the process of value addition of a commodity.
1. Pre-cooling
• Pre-cooling (prompt cooling after harvest) is important for most of the fruits and vegetables because they may deteriorate as much in 1 hr at 32°C.
• In addition to removal of field heat from commodities, pre-cooling also reduces bruise damage from vibration during transit.
• Cooling requirement for a crop vary with the air temperature during harvesting, stage of maturity and nature of crop.
• There are many methods of pre-cooling Viz, cold air (room cooling, forced air cooling), cold water (hydro-cooling), direct contact with ice (contact icing), evaporation of water from the produce (evaporative cooling, vacuum cooling) and combination of vacuum and hydro-cooling (hydrovac cooling).
• Some chemicals (nutrients/growth regulators/ fungicides) can also be mixed with the water used in hydro-cooling to prolong the shelf life by improving nutrient status of crop and preventing the spread of post-harvest diseases.
2. Washing, Cleaning and Trimming
• Before fresh fruits and vegetables are marketed various amounts of cleaning are necessary which typically involves the removal of soil dust, adhering debris, insects and spray residues.
• Chlorine in fresh water is often used as disinfectant to wash the commodity.
• Some fungicides like Diphenylamine (0.1 - 0.25%) or ethoxyquin (0.2 - 0.5%) may be used as post-harvest dip to control the disorders. E.g. Apple superficial scald. For cleaning of some fruit type vegetables (melons, brinjal, tomatoes, cucumber) they should be wiped with damp cloth. Many vegetable need trimming, cutting and removal of unsightly leaves or other vegetative parts.
3. Sorting, Grading and Sizing
• Sorting is done by hand to remove the fruits which are unsuitable to market or storage due to damage by insects, diseases or mechanical injuries.
4. Curing
• Curing is an effective operation to reduce the water loss during storage from hardy vegetables viz, onion, garlic, sweet potato and other tropical root vegetables.
• The curing methods employed for root crops are entirely different than that from the bulbous crops (onions and garlic).
• The curing of root and tuber crops develops periderms over cut, broken or skinned surfaces wound restoration. It helps in the healing of harvest injuries, reduces loss of water and prevents the infection by decay pathogens. Onions and garlic are cured to dry the necks and outer scales. For the curing of onion and garlic, the bulbs are left in the field after harvesting under shade for a few days until the green tops, outer skins and roots are fully dried.
5. Waxing
• Quality retention is a major consideration in modem fresh fruit marketing system.
• Waxes are esters of higher fatty acid with monohydric alcohols and hydrocarbons and some free fatty acids.
• But coating applied to the surface of fruit is commonly called waxes whether or not any component is actually a wax.
• Waxing generally reduces the respiration and transpiration rates, but other chemicals such as fungicides, growth regulators, preservative can also be incorporated specially for reducing microbial spoilage, sprout inhibition etc.
6. Packaging
• Proper or scientific packaging of fresh fruits and vegetables reduces the wastage of commodities by protecting them from mechanical damage, pilferage, dirt, moisture loss and other undesirable physiological changes and pathological deterioration during the course of storage, transportation and subsequent marketing.
• For providing, uniform quality to packed produce, the commodity should be carefully supervised and sorted prior to packaging.
• Packaging cannot improve the quality but it certainly helps in maintaining it as it protects produce against the hazards of journey.
7. Storage
• A number of storage techniques (ground storage, ambient storage, refrigerated storage, air cooled storage, zero energy storage, modified atmospheric storage, hypobaric storage and controlled atmosphere storage) are being used for fruits and vegetables depending upon the nature of the commodity and the storage period intended.