Traditional storage

Traditional storage
    A. TRADITIONAL / LOW COST STORAGE TECHNOLOGIES
    1. In situ/ On site/ Natural or field storage
    In Situ means delaying the harvest until the crop is required and is employed for the root, tuber and rhizomes crops. Crops should be left in the soil until preparation for the market. The land where crop is grown remains occupied and new crop cannot be planted there. This is similar to how citrus and some other fruits are left on the tree.
    Eg.: Roots (carrots, sweet potato, and cassava) tubers (potato) and rhizomes (Ginger).
    Disadvantages: In case of cassava, delayed harvest results in reduced acceptability and starch content and pre harvest losses. The crops should be protected from pest and disease attack, chilling and freezing injuries.

    2. Sand and Coir
    In India, potatoes are traditionally stored longer periods of time, which involves covering the commodity underground with sand.

    3. Bulk storage of dried bulb crops
    Onions, garlic and dried produce are best suited to low humidity in storage. Onions and garlic will sprout if stored at intermediate temperatures. Pungent types of onions have high soluble solids and will store longer than mild or sweet onions, which are rarely stored for more than one month.

    Storage conditions for onion, garlic etc.

    Commodity

    Temp. °C

    RH

    Potential storage duration

    Onions

    0-5

    65-70

    6-8 months

    28-30

    65-70

    1 month

    Garlic

    0

    70

    6-7 months

    28-30

    70

    1 month

    Dried fruits and vegetables

    <10

    55-60

    6-12 months

    For bulk storage of onions or garlic, ventilation systems should be designed to provide air into the store from the bottom of the room at a rate of 2 cubic feet /minute /cubic feet of produce. If produce is in cartons or bins, stacks must allow free movement of air.


    4. Clamp storage of root and tuber crops
    Potatoes for processing are best kept at intermediate temperatures to limit the production of sugars which darken when heated during processing. Potatoes meant for consumption must also be stored in the dark, since the tubers will produce chlorophyll (turning green) and develop the toxic alkaloid solanine if kept in the light. Potatoes stored for use as seed are best stored in diffused light. The chlorophyll and solanine that accumulate will aid to protect the seed potatoes from insect pests and decay organisms.
    Tropical root and tuber crops must be stored at temperatures that will protect the crops from chilling, since chilling injury can cause internal browning, surface pitting and increased susceptibility to decay.

    Commodity

    Temperature °C

    RH (%)

    Potential storage duration

    Potatoes (Fresh market)

    4-7

    95-98

    10 months

    Seed potatoes

    0-2

    95-98

    10 months

    Cassava

    5-8

    80-90

    2-4 weeks

    0-5

    85-95

    6 months

    Sweet potato

    12-14

    85-90

    6 months

    Ginger

    12-14

    65-75

    6 months

    5. Storage using evaporative coolers/ Evaporative cooling
    The principle of evaporation can be used to cool stores by first passing the air into the store through a pad of water. The degree of cooling depends on the original humidity of the air and the efficiency of evaporating surface. Both active and passive evaporative cooling systems are used. In a passive system, the cooling pads are placed over the entrance of the store and kept moist. In active system, air is drawn into the store by a fan through a pad, kept moist by constantly pumping water over it. The latter type is more efficient in cooling but requires an electricity supply.
    Zero Energy Cool Chambers (ZECC)
    It is based on the principle of direct evaporative cooling. It does not require any electricity or power to operate. The materials required to make this chamber are cheap and available easily.
    Design and Construction
    The floor of the storage space is made with a single layer of bricks over which a doubled wall rectangular structure is erected with approximately 7.5 cm space between the inner and the outer brick walls. The outer dimensions of the chamber should be about 165x115x67.5 cm. The cavity between the two walls is filled with river sand. The top of storage space is covered with gunny cloth in a bamboo frame structure. The chamber should be constructed under a shed with a lot of aeration and should be closer to water source.
    Operation: After construction, the whole structure is made wet by sprinkling water once in evening till it is saturated to maintain a lower temperature and higher humidity in it. Direct contact of water with fruits and vegetables should be avoided. Fruits and vegetables should be placed in crates or in suitable baskets and then in the chamber. Maximum and minimum thermometer and a wet and dry thermometer are placed in the chamber to note temperature and relative humidity in the cool chamber.
    Storage life-Storage life of different commodities can be increased by 2 to 3 times as compared to ambient conditions especially during summer.
    Storage life of different commodities in zero energy cool chambers
    Storage life
    TOP

    6. Natural ventilation
    Amongst the wide range of storage systems, this is the most simple. It takes advantage of the natural airflow around the product to remove heat and humidity generated by respiration. Buildings providing some form of protection from the external environment and with gaps for ventilation can be used. Produce can be placed in bulk, bags, boxes, bins, pallets etc. Eg. Onion, garlic and shallot

Last modified: Monday, 11 June 2012, 5:28 AM