Cold Storage

Fresh fruits and vegetables are perishable. Particularly high-breed varieties have a shorter shelf life than the organic produce. Due to green revolution, yield per acre and area under cultivation has increased. Most of fruits & vegetables are seasonal. The produce of all farmers comes to market yard simultaneously as such their prices fall. There is a need to extend their shelf life. The bio-chemical and microbial changes are slow at low temperature. So refrigerated cold storages are used to prolong the shelf life of perishable produce.

1. Modified atmosphere technology is being adhered in ultra-modern plants in developed countries. In such cases of storage carbon-di-oxide and oxygen ratio is varied to slow down the respiratory changes in the stored produce.

2. Cryogenic Tunnel:- Indian Institute of Technology has done experimental work on this technology in collaboration of dept. of Science and Technology. The results are encouraging. Quality of preservation is better and energy consumption is only 10% of usual cold storages.

3. Increasing relative humidity and using ozone:- Mitsubishi electircals of Japan have developed technology, which can be used in conuction with cold storage. In this technology relative humidity is increased to 95 % which reduces evaporation but increases risk of spoilage due to bacteria, which is controlled by ozone.

4. Cold storages: - commercial refrigerated preservation of perishable commodities is a short-term process. Costly produce like dry-fruits, potatoes (seed) oranges, chemicals, processed foods like fruit juices, pulp, concentrate, dairy products, frozen meals, fish, poultry etc are being stored in cold storages. The development of cold storages including cold chain for transport has an important role to play in reducing the wastage of perishable agro-produce, and thus providing renumerative prices to growers.

Technical aspects: - at present there are two popular refrigerants in the Market - Freon & Ammonia. It may be noted that in near future CFC refrigerants will be banned. Cold storage consists of many rooms. Each room should be separated by insulation and protected from moisture. Partitions should be insulated on both sides. Before keeping fruits and vegetables in the cold storage, bad ones should be removed. The sorted material should be packed in boxes. Temperature and humidity should be kept according to the product. For certain Fruits like grapes, pre-cooling is necessary.

Optimum storage conditions for fruits
Sr No.	Item	Temp. ⁰F	Cold storage life in weeks	Remarks
1	Apple	32-35	7-26	Small fruits keep better
2	Bananas	55-60	2-3	-
3	Guavava	47-50	3-4	-
4	Grapes	30-32	4-6	Fumigation with 1-2% sulphur oxide before storage and storage life is increased to 12 weeks
5	Lemons	50-55	9-13	Lemons for storage be picked at the greenish yellow colour.
6	Mangoes	45-50	4-6
7	Pineapple	50-55	3-4
Optimum storage conditions for vegetables R-H-85 to 95 % except for Beet root, cabbage, Raddish, Turnips and Peas where RH should be 90 to 95 %
1	Beans	32-35	2-3	Need more ventilation
2	Beet root	32-35	6-8	-
3	Brinjals	47-50	3-4	Big brinjals keep better
4	Carrots	32-35	13-17	-
5	Cauliflower	34-35	4 to 6	Only firm and compact heads should be stored
6	Cabbage	32-35	9-13	Only firm and compact heads be stored
7	Onions	32-35	17-26	-
8	Potatoes	37-38	26-35	-
9	Radish	32-35	6-8	-
10	Turnips	32-35	13-17	-
11	Peas	32-35	2-3	Peas need pre-cooling and more ventilation

Cold Storage

Optimum storage conditions for fruits