Grain Storage
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Transcript of Grain Storage
IMPORTANCE OF MOISTURE AND TEMPERATURE IN SAFE STORAGE
OF FOOD GRAINS
Factors affecting quality of grains during storagePhysical factors
TemperatureMoisture & relative humidity
Chemical factorsBiochemical deteriorationPesticides
Biological factorsInsects and mitesRatsBirdsMicro-organisms
Engineering factorsStructural Factors
Bag storage Bulk storage
Handling equipments
Abiotic variablesMoistureTemperature
Biotic variablesMicroorganismsInsectsMitesProperties of the grains
Scientifically visualized controls bring ideal balance in the relationship of the abiotic variables with the biotic variables, which ensure proper grain preservation and soundness. When these relationships got disturbed due to unfavourable storage conditions or defective practices, spoilage occurs.
So the scientific storage of food grains in India is of para mount importance
The effects of temperature and moisture content in safe storage of food grains are inter related
Grains are living beings and respireDuring respiration oxygen is taken up and and inherent carbohydrates are catabolised to CO2 and water. In the process heat is also produced.This decomposition causes a material loss of weight, commonly known as dry matter loss.
Respiration activity is mainly influenced by – Temperature and moisture content
Upto moisture content of 15% , this activity is extremely lowFurther 2% rise from 15% to 17% will increase the CO2 production by 80 times.
Grains have low thermal conductivityThe heat produced during respiration is accumulated and grain temperature rises.
The grain being hygroscopic in nature picks up and gives up moisture from atmosphere and attains equilibrium.
Moisture content (%) g dry matter Loss (%)
11.0 0.21 0.000214.5 0.96 0.00117.0 83.90 0.0820.5 244.8 0.2433.0 1364.00 1.36
Loss of dry matter through respiration of 100kg wheat at 180C within 10 days
Temperature 0C g dry matter Loss (%)
18.0 0.96 0.00130 5.1 0.00540 13.6 0.01352 169.8 0.017
Loss of dry matter through respiration of 100kg wheat at 14.5% within 10 days
Mean values of dry matter loss for a storage period of six months15.0% moisture, at 200C = 0.38% dry matter loss 15.0% moisture, at 60C = 0.38% dry matter loss
Sr. No. Stored cereal Safe moisture content (WB, %)
1 Wheat 12.0
2 Paddy 14.0
3 Rice 13.0
4 Corn 13.0
5 Soybean 12.0
Critical moisture content(%) for safe storage of cereal grains
Harvesting and drying• Grain moisture
content (12-14%)• Minimize cracked and
broken grain during processing
• Don’t mix old and new grain
MoistureMigration
ResultsFrom
Non-uniformTemperature
Hot spot caused by insects
Hot spot spreading
From warm moist air
Condensation near cool surface
Damage due to moisture rising from hot spot
mould
Sprouting of grains
Spoilage of grains due to development of insect and fungi
Outside air temperature above grain temperature
Damage at bottom
Outside air temperature below grain temperature
Damage at top
Management for successful storage:
Control of temperature
Control of seed moisture
Control of temperature Temperature is one of the most important environmental factors which influence seed viability and vigour during storage, the lower the temperature; the longer the seeds maintain germination capacity. Thus, temperature control is an important consideration in building seed storage. Temperature control may be achieved in one of the following ways: Ventilation Insulation Refrigeration
These methods are not mutually exclusive, and are normally used to supplement each other. Ventilation Ventilation could be used to reduce seed temperature and seed moisture content, if used judiciously. In addition, it also helps prevent hot spots from developing; the formation of convection air currents and maintenance of uniform seed moisture content and temperature. Time of ventilation: Whenever the outside temperature of air and relative humidity are low enough to benefit the seeds, either by reducing seed temperature or seed moisture content, the ventilating fans (exhaust fans) can be turned on.
Advantages of Silo Storage• Space required in Silo facility is 1/3rd against
conventional storage• Quick transaction of farmer’s produce in most efficient
& transparent manner• Lesser threat from weather & hence lesser possibility of
grain spoilage• Efficient clearing of mandis during season & usage of
silos as storage point after the procurement season is over
• Economical linkages to Rail heads• No glut in mandis• Elimination of unproductive operations & reduced
losses
Contd…
• Scarcity of labour & inefficient labour operations further justify need for silos
• Right from farm till its sale in mandi, foodgrains are handled in bulk. Hence Silo Storage is best match for mechanical bulk handling in mandis
• Some existing storage facilities in Punjab/ Haryana are far from procurement as well as Rail heads resulting in excessive transportation cost.
Contd…..• 90% of wheat arrives in Punjab/ Haryana Mandis in
just 20 days resulting in choking of mandis• Increasing arrivals require expansion & upgradation of
Mandis• Horizontal expansion needs heavy investments in land• Many mandis are situated in commercial areas, where
further expansion may not be feasible. Alternately, these can be profitably used for other commercial ventures
• Booming economy & more employment opportunities in labor surplus states like Bihar, UP, Orissa has created labor shortage in Punjab/ Haryana
Contd…• Inefficient manual operations carried out in
mandis at present cannot cope up with peak marketing requirements of state
• Limited resources of transporters result in non lifting of stocks on day to day basis causing choking of mandis during peak season
• Unpredictable weather during season threatens procurement process besides spoiling the stocks lying in open yard
• Present manual operation creates lot of environmental problems
• Weighment & Quality Check System in present mandis is not effectively implemented due to inherent limitations of the manual system
The following table shows the EMC of paddy under different storage conditions. The green colored areas represent the desirable environmental conditions for safe storage of paddy or rough rice in the tropics. The yellow areas represent conditions for safe seed storage. Grain needs to be stored at less than 14% moisture and seed at less than 12%.
At the time of storage
Initial wt of wheat = 100 kgIMC = 12%Wt of dry matter (BDW) = 88 kg
At the time of dispatch
Moisture content = 13%Final wt of wheat = W
100*WBDWW
MC
W= 101.149 kg
At the time of dispatch
Moisture content = 11%Final wt of wheat = W
W= 98.876 kg