1、 Rice
1. Storage characteristics of rice: the glume of rice is hard, which can protect the grain and resist the influence of insects and external temperature and humidity to a certain extent. Therefore, rice is easier to keep than ordinary finished grain. However, rice is easy to sprout and is not resistant to high temperature, which requires special attention.
Most rice (such as indica rice) has no post ripening period, and has physiological maturity and germination ability at the time of harvest. At the same time, the water absorption required for rice germination is low. Therefore, if the rice is not harvested, threshed and dried in time in case of continuous rain, the rice will germinate in the field and site. The rice in storage is also easy to sprout if it condenses, returns to moisture or leaks rain. Rice is not threshed and dried in time, and even the grass is stacked, which is easy to Rett yellow. The quality and storage stability of sprouted and yellow retting rice are greatly reduced.
Rice is not resistant to high temperature. Rice in summer is easy to age. Rice exposed to the hot sun or suddenly cold after exposure is easy to "burst the waist".
Soon after the new rice is put into storage, if the temperature drops, it often condenses on the surface of the grain pile, increasing the surface grain moisture, which is unfavorable for storage. The surface grain moisture should be reduced in time.
2. Storage method of rice
Ensure the quality of stored rice: rice with large moisture, many impurities and many imperfect grains is easy to heat and mildew, but not stored for a long time. Therefore, improving the quality of stored rice is the key to safe storage of rice. The safe moisture standard of rice shall be determined according to the variety, season, region and climate conditions. Generally, indica rice is less than 13% and japonica rice is less than 14%. The less impurities and imperfect particles, the better. If the stored rice has large moisture and many impurities, it should be stored in grades, dried or dried in time, and screened or air selected to remove impurities.
Timely ventilation: due to vigorous breathing, mild grain and high moisture, new rice should be ventilated in time to reduce temperature and precipitation. Especially when it is cool in autumn, the temperature difference inside and outside the grain pile is large. At this time, ventilation should be strengthened, combined with deep turning of the grain surface to distribute the damp heat of the grain pile to prevent condensation. Mechanical ventilation can be used if possible.
Low temperature sealing: make full use of the cold and dry weather in winter for ventilation to reduce the grain temperature to below 10 ℃ and the moisture to within the safety standard. Seal the gland before the temperature rises in spring, so as to spend the summer safely.
2、 Wheat
Storage characteristics of Wheat
Strong moisture absorption: wheat seed coat is thin, loose tissue structure and strong moisture absorption capacity.
Long post ripening period: wheat has a long post ripening period. The length of post ripening period is also different with different varieties. The post ripening period of most varieties ranges from two weeks to two months. Wheat with appropriate water content, after the completion of post ripening, the quality and storage stability are improved.
High temperature resistance: wheat has strong heat resistance. According to the experiment, the wheat with 17% water content should be dried when the temperature does not exceed 46 ℃; The enzyme activity will not be reduced when the sun exposure temperature is not more than 54 ℃. The process quality of ground wheat flour is not reduced, but improved. It is made into steamed bread soft and expanded. This provides a basis for high-temperature drying or high-temperature pest control of wheat.
Storage resistance: the biggest advantage of wheat is its good storage resistance. The respiration of wheat after ripening is weak, which is lower than that of other cereals. The water content of normal wheat is within the standard (12.5%), and there is no significant change in its edible quality when it is stored at room temperature for 3-5 years or at low temperature (15 ℃) for 5-8 years.
Vulnerable to insects: wheat is a grain species with poor insect resistance and high infection rate. Except for a few legume specific insects, wheat can be infected by almost all stored grain pests, among which corn elephant and wheat moth are the most serious. It is summer when wheat is ripe, harvested and put into storage. It is at the stage of breeding and occurrence of pests. The temperature is high after putting into storage. In case of rain, it will cause very suitable conditions for the occurrence of pests.
2. Storage method of Wheat
Strictly control moisture: due to the strong moisture absorption capacity of wheat, pay attention to precipitation and moisture-proof during wheat storage. The high-temperature conditions in summer after wheat harvest should be fully used for exposure, so that the water content of wheat can be controlled below 12.5%, and then put into storage. After wheat is put into storage, moisture-proof measures should be taken, and attention should be paid to the possible water stratification and "topping" of the upper layer during post ripening.
Hot storage and airtight storage: wheat is stored in airtight storage while hot, which is a traditional wheat storage method in China. The water content of wheat can be reduced by sun exposure. At the same time, the effect of high temperature insecticidal and bacterial control can be obtained in the process of exposure and warehouse sealing. For newly harvested wheat, it can promote the completion of post ripening. Due to the extinction of pests, the water content and bacteria carrying capacity of wheat are reduced, and the respiratory intensity is greatly weakened, which can make wheat stored safely for a long time.
The specific operation method of wheat warehousing while hot is as follows: in the midsummer of the third volt, select the sunny and high temperature weather, sun the wheat temperature to about 50 ℃, maintain the high temperature for 2 hours, and reduce the moisture to less than 12.5%. Gather around 3 pm, enter the warehouse while hot, and seal the whole warehouse, so that the grain temperature is at 46 ℃ left and right for about 10 days, which can kill all pests. After that, the grain temperature gradually decreased, balanced with the warehouse temperature, and transferred to normal closed storage.
In addition, the warehouses, equipment and appliances used for hot warehousing and closed storage need to be disinfected in advance.
Low temperature closed storage: Although wheat can withstand high temperature, it will reduce the quality of wheat if it is stored at high temperature for a long time. Therefore, the wheat can be fully dissipated by natural ventilation or mechanical ventilation after cool autumn, and the gland can be sealed before warm spring to maintain low temperature. Low temperature storage is the basic method for long-term safe storage of wheat. Keeping wheat at a certain low temperature is good for prolonging seed life and maintaining quality.
Wheat can also be frozen to maintain good quality. For example, dry wheat can be stored at a low temperature of - 5 ℃, which is conducive to the enhancement of vitality. Therefore, using the severe cold and low temperature in winter to turn the warehouse, remove impurities and freeze, reduce the wheat temperature to about 0 ℃, and then seal it while it is cold, which has a good effect on eliminating the overwintering pests in the wheat pile. Low temperature airtight can be stored for a long time, but it should be strictly prevented from contacting with damp and hot airflow to avoid condensation on the surface of wheat pile.
3、 Corn
1. Storage characteristics of corn
Corn has large original moisture and uneven maturity. Corn is in the north of China's main production area. The weather is cold at the time of harvest. In addition, there are bracts at the ear of corn, so the plant cannot be fully sun dried, so the original moisture of corn is generally high. The moisture content of newly harvested corn is generally 15-20% in North China and 20-30% in Northeast and Inner Mongolia. The maturity of maize is often uneven, which is due to the different pollination time between the top and base of the same ear, resulting in insufficient maturity of the top grain. Corn with uneven maturity is not conducive to safe storage.
The embryo of corn is large and breathing vigorously. The embryo of maize accounts for almost 1 / 3 of the total grain volume and 10% ~ 12% of the grain weight. Corn embryo contains more than 30% protein and more soluble sugar, so it has strong moisture absorption and vigorous respiration. According to the experiment, the respiratory intensity of normal corn is 8 ~ 11 times higher than that of normal wheat. The absorption and emission of water in maize are mainly carried out through the embryo.
Corn embryo contains much fat and is easy to rancidity. Corn embryo contains 77-89% fat in the whole grain, so the fatty acid value of embryo is always higher than that of endosperm, and rancidity starts from embryo first.
The amount of bacteria carried in maize embryo is large and easy to mildew. Maize embryo is rich in nutrition and has more microbial attachment. According to the measurement, after a period of storage, the amount of bacteria carried by corn is much higher than that of other cereal grains. Corn embryo is the first place to be damaged by insects and molds. After the embryo absorbs moisture, the molds multiply in large numbers and begin to mildew at a suitable temperature.
(2) Corn storage method
The key to safe storage of corn is to improve the storage quality and reduce grain moisture. Due to the great differences in temperature and humidity around the country, corresponding storage measures should be taken according to the specific local conditions.
Grading: Warehousing by moisture. When entering the warehouse, corn should be stored separately according to different water content and grades. Lay a preliminary foundation for safe storage. Corn with high moisture content shall be dried before storage.
Low temperature and airtight storage: suitable for low temperature and dry storage. There are two methods, one is drying and sealing, and the other is low-temperature freezing and sealing. The corn harvested in the South can be fully dried if possible, and then screened into the warehouse for closed storage after being reduced to safe moisture. Due to the limitation of temperature after corn harvest in northern China, it is very difficult for high moisture corn to fall to safe moisture. In addition to drying and precipitation, low-temperature freezing can be basically used for closed storage. The method is to use the cold and dry weather in winter to cool down, and the grain temperature can be reduced to below - 10 ℃, then sift and remove the frost and impurities, and put them into the warehouse for closed storage in low temperature and sunny days.
Corn ear storage: corn does not thresh. Ear storage is a relatively mature experience, which has been widely used by farmers in China for a long time. Due to the large porosity (up to 51.7%) in the ear pile, good ventilation conditions and low temperature season, although the respiratory intensity of the ear of high moisture corn is still large, it can also maintain the balance of heat metabolism and the change of heap temperature is small. Under the long-term ventilation conditions in winter and spring, the corn can be gradually dried. When the water content drops to 14.5% ~ 15%, it can be threshed and transferred to grain storage.
During the storage of corn ear, the embryo of grain is buried in the ear shaft, which has a certain protective effect against insect and mildew. In addition, the nutrients in the cob can continue to be transported to the grain at the initial stage to increase the nutrients in the grain.
4、 Soybeans
Storage characteristics of soybean
Soybean has round grain, smooth seed coat, hard grain and strong resistance to insects and molds, but damaged soybean is easy to deteriorate. Soybean seeds are rich in protein and fat. They are easy to absorb moisture when the air humidity is high. After the influence of high temperature in summer, they are easy to change color and taste, and serious oil immersion occurs. At the same time, high temperature and high humidity are also easy to reduce the germination rate of soybean.
When the relative humidity is below 70%, the moisture absorption of soybean is weaker than that of corn and wheat, but when the relative humidity is 90%, the equilibrium moisture of soybean is greater than that of corn and wheat. Therefore, moisture-proof work should be done well in the storage of soybean.
Easy to remove oil and red change. When the moisture content of soybean is more than 13%, with the increase of temperature, firstly, the bean grain softens, and then the color of the two cotyledons near the embryo turns red, commonly known as "red eye". Later, the internal red of the bean grain deepens and gradually expands, commonly known as "red change". In serious cases, the cotyledons are waxy and transparent, with oil immersion and peeling.
2. Storage method of soybean
Fully dry: after soybean threshing, we should pay close attention to the whole drying to reduce the moisture. The moisture content of soybean that needs long-term storage shall not exceed 12.5%. No matter how high the moisture content is, it is easy to mildew.
Timely ventilation: the moisture among newly stored soybean seeds is uneven, coupled with post ripening effect, vigorous breathing, and more moisture and heat accumulate in the soybean pile. At the same time, it is in the season of falling temperature, which is very easy to produce dew condensation. Therefore, soybeans should be ventilated and dissipated in time for about 3 ~ 4 weeks, so as to enhance the storage resistance of soybeans.
Low temperature sealing: the soybean is frozen in the severe winter season, and the low temperature sealing storage can not only isolate the influence of external temperature and humidity and pest infection, but also prevent oil immersion and red change, which is conducive to maintaining the quality of soybean.
