INTRODUCTION• All fresh horticultural crops are high in water content and are subjected to desiccation (wilting, shrivelling) and to mechanical injury.• Various authorities have estimated that 20-30 % of fresh horticultural produce is lost after harvest and these losses can assume considerable economic and social importance.• That is why, these perishable commodities need very careful handling at every stage so that deterioration of produce is restricted as much as possible during the period between harvest and consumption.
HARVEST• Fruits harvested too early may lack flavour and may not ripen properly, while produce harvested too late may be fibrous or have very limited market life.• The level of maturity actually helps in selection of storage methods, estimation of shelf life, selection of processing operations for value addition etc. The maturity has been divided into two categories i.e. physiological maturity and horticultural maturity.
• Physiological maturity: It is the stage when a fruit is capable of further development or ripening when it is harvested i.e. ready for eating or processing.• Horticultural maturity: It refers to the stage of development when plant and plant part possesses the pre-requisites for use by consumers for a particular purpose i.e. ready for harvest.
WHY AFTER HARVEST IS IMPORTANT ?• Domestic products are not exported regionally or internationally because they do not meet the basic standards of sizing, colour, shape, maturity, packaging, labelling, etc.• This is true for products for the fresh market as well as products destined for processing.• Unfortunately, the result is that domestic products have lost market share locally to imports and, at the same time, have not penetrated export markets.• Further impeding expansion of this sector is the nearly total lack of storage facilities to maintain product integrity .
• Higher prices for fresh fruits and vegetables require improved quality.• High quality can only be achieved through proper grading, sorting, packing, storage and handling of fresh fruits and vegetables but requires a certain level of new technology to accomplish it.
• It is important to minimize mechanical damage by rough handling and bruising during the different steps of pack house operations. Secondly the pack house operations should be carried out in shaded area.• Shade can be created using locally available materials like, shade cloth, woven mats, plastic tarps or a canvas sheet hung from temporary poles.• Shade alone can reduce air temperatures surrounding the produce by 8-17°C.
DUMPING• i) Dumping: The first step ofhandling is known asdumping. It should be donegently either using water ordry dumping. Wet dumpingcan be done by immersingthe produce in water. Itreduces mechanical injury,bruising, abrasions on thefruits, since water is moregentle on produce. The drydumping is done by softbrushes fitted on the slopedramp or moving conveyorbelts. It will help in removingdust and dirt on the fruits.
ii) Pre-sorting: It is done to remove injured, decayed, mis- shapen fruits. It will save energy and money because culls will not be handled, cooled, packed or transported. Removing decaying fruits are especially important, because these will limit the spread of infection to other healthy fruits during handling.
WASHING AND CLEANING iii) Washing and Cleaning: Washing with chlorine solution (100- 150 ppm) can also be used to control inoculum build up during pack house operations. For best results, the pH of wash solution should be between 6.5-7.5 - Mangoes, bananas should be washed to remove latex. - Kiwifruit should be dry cleaned or brushed after curing or storage.
iv) Sizing / Grading: Grading can be done manually or by automatic grading lines. Size grading can be done subjectively (visually) with the use of standard size gauges. Round produce units can be easily graded by using sizing rings.
Grade designation andquality of fruits :Minimum requirements are : Fruits should be a) clean, round, free from any visible foreign matter b) fresh in appearance, free of pests c) free from damage caused by pests or diseases d) free of any foreign smell and/or taste
METHODS OF PRE-COOLING• - Room cooling• - Forced air cooling• - Hydro cooling• - Vacuum cooling• - Package icing
ROOM COOLING• It is low cost and slow method of cooling. In this method, produce is simply loaded into a cool room and cool air is allowed to circulate among the cartons, sacks, bins or
Advantages:- Produce can be cooled and stored at the same room thus saveson handling costs.- No extra cost for pre-cooling equipment.- Suits for crops, which are marketed soon after harvest.Disadvantages:- It is too slow method of cooling- Space requirements for room cooling are more as compared tostorage.- Unsuitable for packed produce.- Excessive water is lost from the produce due to slow cooling.Horticulture crops suitable for rooms cooling are: apple andcitrus
FORCED AIR COOLING• ii) Forced-air cooling: Forced air-cooling is mostly used for wide range of horticultural produce.• This is the fastest method of pre-cooling. Forced air- cooling pulls or pushes air through the vents/holes in storage containers.• In this method uniform cooling of the produce can be achieved if the stacks of pallet bins are properly aligned.
HYDRO COOLING• iii) Hydro cooling : The use of cold water is an old and effective cooling method used for quickly cooling a wide range of fruits and vegetables before packaging. For the packed commodities it is less used because of difficulty in the movement of water through the containers and because of high cost involved in water tolerant containers. This method of cooling not only avoids water loss but may even add water to the commodity. The hydro cooler normally used are of two types :• a) Shower type : In this type of hydro cooler, cold water is pumped to an overhead perforated pan which produces a shower over the produce which may be in bins or boxes or loose on a conveyer belt passing beneath. The water leaving the produce may be filtered to remove debris, then passed over refrigeration coil where it is recoiled.
• b) Immersion type: In this type of hydro cooler, the produce is brought in contact with cold water by using a conveyor (flume type) or by lowering bins / boxes in tank of water which is continuously cooled by mechanical refrigeration system.
• Advantages :• Less energy is used as compared to forced air cooling.• Hydro cooler can be easily integrated into an packing operations and become a step within a simple packing line.• Moisture loss does not take place.• Disadvantages :• Most of the packages don’t tolerate wetting.• Wax layer of some fruits like pear, plum, apple are removed by using spray type of hydro cooler :• Horticultural produce suitable for hydro cooling are: Mango, peach, cherry, asparagus etc.
• Immersion type hydro coolers usually take longer time to cool produce than shower type cooler. Generally the small quantity chlorine or other chemicals are added in the water to sanitize it.
HYDRO COOLING WATER TREATMENT• The surface of wet commodities provides an excellent site for diseases to thrive.• Typically, hydro cooling water is treated with chlorine to minimize the levels of decay-producing organisms.Chlorine in the form of hypochlorous acid from sodiumhypochlorite• or gaseous chlorine is added to the hydro cooling water, typically• at the level of 50 to 100 ppm.
Vacuum cooling• iv) Vacuum cooling: Vacuum cooling take place by water evaporation from the product at very low air pressure.• In this method, air is pumped out from a larger steel chamber in which the produce is loaded for pre-cooling.• Removal of air results in the reduction of pressure of the atmosphere around the produce, which further lowers, the boiling temperature of its water.• Vacuum cooling cause about 1 per cent produce weight loss (mostly water) for each 6 0 C of cooling.
• Advantages :• Packed produce can be cooled if the pack allows moisture transfer.• Fast and uniform cooling takes place.• Most energy efficient method.• Disadvantages :• High capital cost• Produce losses more moisture
• To overcome the more loss of water from the produce, another method of water spray vacuum is used, (modification of vacuum cooling), called hydro-vac cooling.
v) Package-icing :In some commodities, crushed or flaked ice is packed along with produce for fast cooling.However, as the ice comes in contact with the produce, it melts, and the cooling rate slows considerably.The ice keeps a high relative humidity around the product. Package ice may be finely crushed ice, flake ice or slurry of ice.Packaged icing can be used only with water tolerant, non-chilling sensitive products and with water tolerant packages (waxed fibreboard, plastic or wood).
Wax layer restrictsthe gases interchange. Air in the internal Cavity
PACKAGING• A coordinated system of preparing goods for transport, distribution, storage, retailing and end use.• A means of ensuring safe delivery to the ultimate consumer in sound conditions at minimum cost.
Requirements of a Good Package• Should be environment friendly.• Should have sufficient strength in compression and against impact and vibrations• Should be stable during the entire distribution chain.• Should be compatible with the automatic packing/filling, handling machines (mechanical filling systems)• Should facilitate special treatments like pre- cooling.• Should have consumer appeal.• Should be easily printable.• Should be cost effective.
Materials for Packaging• Wood – boxes, bins, trays, barrels, pallets• Jute/canvas – sacks• Paper and card board – liners, boxes, trays• Plastic – Rigid - crates, pallets, trays• Flexible – films (single & multi layered)• Polystyrene boxes / trays• Combined materials – CFB and plastic• CFB has almost replaced wood and jute and is considered as most important package material to be used in combination with other materials.
Cushioning materials• Dry grass, paddy straw, leaves, saw dust, paper shreds etc. are used as cushioning material for packaging fruits and vegetables• It should dissipate the heat of respiration of the produce• It should be free from infection and should be physiologically inactive• Molded pulp tray, honeycomb portion, cell pack are used replacing the cushioning material
Packaging Type:• i) Bags and Sacks: Paper, polyethylene film, woven polypropylene. These give little protection to the crop from handling and transport damage, potato, onion, cantos etc.• ii) Woven Baskets: These are traditional containers in which crops are placed after harvest. The produce is damaged in these baskets when they are stacked one above the other during transport and distribution.• iii) Wooden field box: These are made from thin pieces of wood, widely spread so they are light in weight and cheep to make. These can be used for all types of fruits and vegetables.• .
• iv) Plastic field boxes: They are strong and durable. They are made from moulded polyvinyl chloride, poly propylene or polyethylene. They have smooth surface, which does not damage the produce. Initially, they are expensive to buy, but can be used repeatedly.• v) Pallet boxes: They are most commonly base on the standard size for a European pallet of 1 x 1.2 m and about 0.5 m high. These have capacity of about 500 kg. They are usually made from wood but plastic ones are also available. They are used for whole range of crops, which are commonly loaded into them in the field and transported directly to the store.• vi) Fibreboard boxes: They are made from either laminated or more commonly corrugated fibreboard. They may be used for directly field packing of produce and transported to pack house or destination market
Lets sum upPostharvest handling is the final stage in theprocess of producing high quality freshproduce.Being able to maintain a level of freshness fromthe field to the dinner table presents manychallenges. A grower who can meet thesechallenges, will be able to expand his or hermarketing opportunities and be better able tocompete in the marketplace.