Cold Storage in Horticulture
Cold Storage is a special kind of place, the temperature of, which is kept very low. The function of storage is to provide favorable environment which minimizes the deterioration until they are finally consumed. Proper temperature and humidity plays important role to keep the produce in good condition. Reducing the temperature, slow down the rate of respiration, ethylene production and its action as well as biological changes, transpiration losses.
The advantages of storage are:
Storage stabilizes the prices of produce by lengthening the availability.
More uniform distribution is possible
Availability of produce in off-season for a particular place is made possible.
Among various methods of storage, cold storage is most common and very effective tool. Depending upon the type of commodity, the temperature in cold storage is maintained such as in refrigerated storage.
The basic features of cold storage are:
- Well insulation:
There may be movement of high temperature from outside and leakage of low temperature from storage. So, to prevent this insulation is necessary. The insulating material may be fiber glass, vermiculite etc. which has low heat conductivity, moisture resistant, easy to install, in expensive, and should not contain volatile substances that may impair the quality of fruits and vegetables.
- Vapour barrier:
Vapour barrier is installed between outside wall and the insulation to prevent moisture inflow.
- Ammonia (NH3):
Ammonia is the commonly used refrigerant gas generally used in big commercial storage.
- Thermo expansion (TX) valve:
It controls the flow of gas. It opens when the temperature is high and works in co-ordination with thermostat which closes when the required temperature is achieved.
Components of Refrigeration Plant:
Here, the refrigerant gas either ammonia or halogenated hydrocarbons is compressed.
This may be either air cooled or water cooled in which the hot gas is cooled and condensed to a liquid.
This is a cooling coils in which the liquid is permitted to boil and thus removes heat from its surroundings. Fans are necessary to circulate the storage air over the cooling coils of the evaporator and through the stack of produce in the store. Moving air is the main agent for transfer of the heat from the contents of store and from leakage into the store, to the coils.