Advantages :
• Less energy is used as compared to forced air cooling.
• Hydrocooler 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
hydrocooler :
Horticultural produce suitable for hydrocooling are: Mango, peach, cherry, sparagus etc.
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. As the pressure falls, the water boils quickly removing the heat from the produce. 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. Liquid icing distributes the ice throughout the container, achieving better contact with the product. Packaged icing can be used only with water tolerant, non- chilling sensitive products and with water tolerant packages (waxed fiberboard, plastic or wood).
C. Packaging of Horticulture Produce
What is Packing? According to UK institute of packaging