grain lecture 13.pptx power point presentation

grain lecture 13.pptx power point presentation

1. Food Grain Storage

2. Post harvest loss in Bangladesh Product name Harvesting loss % Transporting loss % Threshing loss % Parboiling loss % Drying loss % Storage loss % Total loss (%) Rice 1.71 1.02 1.37 0.02 2.30 3.76 9.81 Wheat 0.77 0.09 0.65 0.62 1.54 3.62 Maize 0.33 0.12 0.55 0.62 2.5 4.07

3. Grain Storage Principles Food grains are living organisms . Hence, the grain should be stored as a living seed. A grain is physiologically quite stable after harvesting and this stability as well as its viability should be preserved in a good storage method. Under natural conditions, however, stored grain undergoes chemical changes within itself. Its further deterioration is caused by external living organisms. Initially, the rate of deterioration is slow, but as the favorable combinations of variables are set and the storage period is prolonged, a very high loss in grain quality and quantity occurs. The major variables that cause various changes and deteriorations in food grains during storage are given as follows : 1. Physical: temperature and humidity 2. Chemical: moisture and oxygen (or O 2 :CO 2 ) 3. Physiological: respiration and heating 4. Biological: insects, fungi, molds, mites, microorganisms, and rodents

4. The deterioration of food grains may be either qualitative or quantitative, or both. Insects, microorganisms, fungi, molds, mites, and rodents may cause both these damages. Moisture and temperature are the most crucial ones as far as storage of food grains is concerned. The soundness of grain is also an important factor from the standpoint of viability.

5. Moisture The moisture of food grain is the first factor to be paid serious attention as it limits the development of bacteria, fungi, mites, and insects that cause spoilage of stored grains. The important points to be kept in mind while planning safe storage are that a . moisture contents of grains below 13% arrest the growth of most of the microorganisms and mites ; b. moisture contents below 10% limit development of most of the stored grain insect and pests; c . moisture contents within a grain bulk are seldom uniformly distributed and are changeable. The limit of moisture for safe storage of cereal grains , in regard to insect pest and microorganism infestation, is about 13%–14%, which is equilibrated with the atmospheric relative humidity of around 70%–75%. If a cereal grain is to be stored for a long period, its moisture should be below 12%.

6. Temperature The temperature is another important basic factor to be considered along with the grain moisture and equilibrium relative humidity. The relative humidity, which is in equilibrium with the grain moisture, varies with the temperature. The metabolic heat produced exclusively by dry grain is about 1 × 10 −7 cal /sec and by wet grain is ∼1.3 × 10 5 cal /sec . In considering temperature for safe grain storage system, the following important points are to be kept in mind: ( i ) generally, mites do not develop below 5°C nor insect below 15°C ; (ii) most of the storage fungi do not develop below 0°C ; and (iii) the effect of temperature on an organism can be correlated with the amount of grain moisture. The rate of respiration of grain, the growth of microorganisms, and the chemical and enzymatic reactions during storage also accelerate up to a certain Temperature When the grain temperature rises to around 20°C , it starts getting easily infested with insects and microorganisms, and, at the same time, its rate of respiration becomes rapid with the expense of chemical constituents. The grain temperature is always to be considered in conjunction with its moisture content.

7. Changes in Food Grains during Storage Chemical Changes Oxidation, enzymatic reactions, and respiration influence the chemical changes in cereal grains during storage. All cereal grains contain certain enzymes that decompose their constituents such as starch, proteins, and lipids. These enzymatic activities are enhanced with the rise in grain moisture and temperature. Starch , the main constituent of rice , is converted into dextrins and maltose by the action of amylase in the rice grain . It results in an increase in reducing sugars. But in grain this development is not pronounced when the moisture content of rice is around 14% and the temperature is also at a lower level. When moisture content of a rice kernel is considerably at a higher level, the carbohydrates are fermented. As a result, alcohol and acetic acid are produced with the formation of acid odor . Besides enzymatic reactions, oxidation by the surrounding air causes changes in color and flavor. Regarding other constituents of cereal grains, vitamins are gradually diminished under ordinary storage conditions.

8. Physiological Changes Respiration The life of a food grain is manifested by respiration. In aerobic respiration , a complete oxidation of the hexose yields carbon dioxide, water , and energy . In anaerobic respiration , hexose is incompletely decomposed into carbon dioxide, ethyl alcohol, and energy. Direct consequences of respiration are the loss of mass and gain in moisture content of the grain, rise in the level of carbon dioxide in the intergranular air space, and rise in the temperature of the grain. The respiration rates of freshly harvested grains are different from those of old grains and grains damaged by insects, fungi, and molds . The rate of respiration is high for the old grain and the pest-infested grain compared to the fresh grain. The molds, etc., respire at much higher rates compared to the grain itself . Storing cereal grains under vacuum or airtight conditions appears to be very effective, but anaerobic respiration of the grain at high moisture content makes it unsuitable. The checked and cracked grains have higher respiratory rates than the whole grains under the same condition.

9. Sprouting Sprouting of the grain during storage occurs mainly owing to generation of heat as a result of infestation. A grain sprouts only when its moisture content exceeds certain limit of moisture content of 30%–35 %. Heating The stored grain is sometimes heated up by itself without any external cause. This spontaneous heating can be attributed to the respiration of grain in combination with the respiration of infested pests. Heating usually occurs when grain is stored in bulk. By respiration alone, however, the temperature may not exceed above 35°C. Under favorable conditions, the growth of microorganisms is very rapid and the combined effects of respirations become high, generating more heat. Of the total heating phenomena, 60%– 70% of heating can be ascribed to the respiration of pests .

10. Types of Grain Spoilage Reduction in Mass About 15 mg of rice kernel can be eaten away by a grain weevil during its growth from egg to adult. A female weevil breeding through three generations per year has the biotic potential of reproducing 1,500,000 offsprings , which are likely to consume 1,500,000 kernels of rice. It is also known that warehouse moth, Ephestia elutella , attacks the embryo of wheat kernels making it unfit for germination . Spoilage of Grains by Heating Heating of grain sometimes is brought about by insect and pest infestation, which ultimately causes serious grain damage. Reduction in Seed Germination A seed grain attacked by a germ eater is not likely to germinate. In consequence, germination of seed grains will be seriously affected. Contamination of Grains by Insects Food grains, specially the milled products contaminated with dead bodies of insects and their excreta and secretions, often lead to a serious loss of grain quality .

11. Grain Storage Pests Among all the grain storage insects, the following 12 species are considered important: ( i )the Khapra beetle; ( ii) the borer beetle; ( iii) the grain weevil; ( iv) the rice moth ; ( v) the grain moth; ( vi) the meal moth; ( vii) the pulses beetle; ( viii) the flour moth ; ( ix) the red rust flour beetle; ( x) the long headed flour beetle; ( xi) the saw toothed grain beetle; and ( xii) the flat grain beetle.

12. Control of Stored Food Grain Pests Food grain pests can be controlled by preventive and curative methods It is always desirable that preventive measures are taken before the occurrence of infestation and subsequently curative measures have to be taken. The preventive measures are undertaken to avoid infestation by the pests, while the curative measures are used to wipe out any kind of infestation. Preventive Measures Preventive measures need consistent and thorough application at frequent intervals. However, preventive methods are divided into the following heads: ( 1)physical and mechanical measures : ( i ) drying; (ii) cooling by aeration; (iii) airtight storage; (iv) low temperature storage; and (v) protective packaging. ; (2) chemical measures : ( i ) grain protectants ; (ii) attractants; and (iii) repellants.; (3) Hygienic measures : The entire storage is to be kept under clean and hygienic condition.

13. Curative Measures Among the curative measures, the chemical methods are the most effective, which involve the use of insecticides, are toxic to man, and require special protective devices to safeguard the lives of the personnel applying these chemicals. Curative measures are ( i ) physical methods; (ii) mechanical methods; (iii) chemical methods; and (iv) biological methods. Physical Methods Heating All species of stored grain pests at any stage of development will be killed if these are exposed to a temperature of 60°C for more than 10 min or to 50°C for 2 h. Radiation Irradiation of insects by β-rays or γ-rays causes physical disorder such as loss of their reproductive power and lives even. The γ-rays have a strong penetrating power and have the potential to be the most effective method of control of grain storage pests.

14. Mechanical Methods Centrifugal force can be effectively utilized for this method. In flour mills, the impact of the flour against the rotating disks and housing of the entoleter is so great that all stages of insects and mites, including the eggs, are killed. The flour thus treated with the centrifugal force comes out of the machine. Chemical Methods The chemical control methods employ the following: spraying; (b) fogging; (c) dusting; (d) vaporizers; and (e) fumigation.

15. Fumigation Fumigation is an insect-controlling method of exposing stored grains to a lethal concentration of highly toxic gas long enough to kill the insects. Fumigants are the effective chemicals for killing stored grain pests. In the gaseous phase, fumigants can penetrate through stored grains anywhere in bags on stacks or in bulk and mill the hiding insects. These do not have any residual effect.

16. Principles of Fumigation After application of fumigant, generally it starts vaporizing . The rate of vaporization mainly depends upon the kind of fumigant, method of application, temperature, and air flow rate. Both liquid and gaseous fumigants are common. The low boiling fumigant methyl bromide , which is in gaseous form at room temperature, is called gaseous fumigant. Ethylene bromide , having comparatively a high boiling point, remains in a liquid state at room temperature and is known as a liquid fumigant . There are also solid types of fumigants such as aluminum phosphide tablet . They react with the atmospheric moisture to form hydrogen phosphide gas that has lethal effect on microorganisms.

17. Food Grain Storage Structures Generally, food grains are stored in traditional or improved rural storage structures in urban warehouses/ godowns and in advanced large silos . The farmers usually store their produce in either aboveground or underground storage structures. In most cases, local agricultural wastes and minerals are used. These structures are made of bamboo, wood, earthenware, cement concrete, stones, or bricks. capacities of these vary from 250 to 5000 kg . However, higher capacities of these are also available. Nowadays, some progressive farmers use plastic and metallic bins also.

18. Who stores grain  Farmers - large number / small capacity  Processing units - small number / medium capacity  Government - large quantity to store  Corporates – large quantity

19. Storage Methods / Technologies Bag Storage -Warehousing (house-type structures) -Permanent plinths (outdoor storage with bags stacked on plinths and covered by tarpaulins) Bulk Storage - concrete silos - steel silos -bag silos - bunker silo -open bulk heads (grain held outdoors between pre fabricated steel walls & covered with PVC sheet )

20. Stacking of Jute Bags

21. SILOS – 5000 MT

22. Table A Merits and Demerits of Bag and Bulk Storage

23. Rural Storage Structures Steel Bin It is an outdoor structure of a prefabricated steel bin with a hopper bottom. It is made of a 16 gauge curved MS sheet . It has also metallic ladder and pulley arrangement for filling the grains

24. Aluminum Bin It is an outdoor structure, circular in shape. The bin consists of a cylindrical body of several corrugated aluminum-curved sheets and a conical roof made of flat aluminum sheets. Bolts and nuts are used for assembly of the body and the roof. This bin is constructed on a platform or plinth of 60 cm height , which provides a permanent system against ground moisture. At the same time, the spout that is embedded in the platform allows for easy bagging of the grain. The bin is filled through a manhole at the roof. Both the manhole and the spout are provided with locking arrangements.

25. RCC Bin The RCC storage structure is circular and waterproof . Its capacity varies from 1.5 to 6 tons. It can be built at the site. The bins having capacity less than 6 tons can be made with 30 cm high RCC rings . The joints of the rings are sealed with cement. A manhole of 60 cm diameter on the top and sliding door or a spout near the bottom are provided for filling and discharging grains. Slope at the bottom is preferable. The manhole and spout should have locking arrangements. RCC ring

26. Silos A silo is a tall storage structure, which is nothing but a deep bin. Reinforced concrete structure (RCC) has been in use widely in the construction of high capacity silos. Concrete is a durable and economical material, but it should be used in prefabricated or precast form. Steel is perhaps the most common building material used for the construction of modern grain storage facilities.

27. The major advantages of concrete silos are as follows: These structures are moisture proof, vermin proof, and insect proof ; these have high strength, durability, and workability; there is maximum space utilization per ton of stored material with a reasonable cost of storage; practically, no food grain loss takes place in filling, storing, and emptying; and silos are completely fire proof and have a long life . Steel silos have the following main advantages: steel members have high strength and these can be used as prefabricated members; steel silos are gas- and watertight and have long service life; and steel can be readily disassembled or replaced .

28. Economics of Storage Storage in Godowns Generally, in rural godowns , labor charges, maintenance cost, and cost of gunny bags are involved. Bagged storage occupies a much larger storage area for a given weight of stock and the deterioration of the grains will be more if the building is not properly constructed or adequately water and moisture proof. The economics of paddy storage in both village godowns and silos reveals that silo storage is more economical than the traditional bag storage in godowns considering the usual 5% losses that occurs in ill-ventilated godowns . Though capital investment is much higher in silo storage, yet the paddy can be kept clean and safe after mechanical cleaning and drying. These facilities are not easily available in the conventional godown storage.

29. Storage in Silos The modern methods of grain storage in scientifically built godowns and silos are definitely advantageous. The bulk holding of grain is simpler and requires much less floor area in silos . If bulk transportation of grain, either in lorries or in railway wagons, is resorted, the transport cost may become considerably cheaper. The paddy storage in silos posed some problems, one of which was the maintenance of quality during storage . Though 14% is the acceptable grain moisture level for safe storage, damage of grains has been noticed due to variation in the atmospheric relative humidity and temperature particularly during rainy seasons. For safe storage of paddy in silos, a regular aeration system should be there to counter the effects of high atmospheric temperature and relative humidity .