The best temperature for corn drying in a corn dryer.
Why must the temperature of the grain dryer be controlled?
In Heilongjiang, China, drying is an important part of the corn storage process. At present, most grain storage companies in Heilongjiang Province use drying towers as corn drying machinery. However, drying methods and some external factors often affect the quality of corn. First, the structure of the drying tower is unreasonable, which causes dead corners in the drying room where the corn is heated, resulting in uneven drying; second, the way the corn enters and exits can easily cause damage to the corn; third, the drying fan of the existing corn dryer often sucks high-temperature flue gas and sparks into the pipeline, burns the corn, produces burnt grains, and affects the quality of the corn; fourth, the existing drying tower mainly burns raw coal during the drying process. Most of these raw coals have not been treated in any way. When they are burned in a hand-burned furnace or a machine-burned furnace, the high-temperature flue gas pollutes the corn.
Impact of the drying process on corn quality
The main purpose of drying is to reduce the moisture content of corn in time to ensure safe storage. In the corn drying process, corn not only removes a large amount of moisture, but also destroys the inherent quality of corn to some extent. The main components of corn are starch, protein and fat. When the drying temperature is too high, starch and protein will gelatinize and denature, thus losing their original nutrients. Therefore, the control of drying temperature is crucial to the quality of corn.
Impact on starch
The starch content in corn is 60% to 70%, and starch is composed of starch granules of different sizes. Generally, starch is insoluble in cold water but soluble in hot water. Starch will swell after dissolving in water. The change is not obvious below 57°C. When the temperature exceeds 57°C, especially when the drying temperature is too high, corn starch may gelatinize (appearance burnt), the structure will change, the viscosity of steaming will decrease, it is not easy to form a ball, the flavor will be lost when eaten, the taste will diverge, and there will be a sticky image, resulting in a decrease in corn quality.
Impact on protein and enzymes
The protein content in corn is about 11%. It is a hydrophilic colloid with strong heat sensitivity. Corn will denature at high temperature, and its ability to absorb water and swell will decrease. The higher the temperature, the greater the degree of denaturation. The temperature should be strictly controlled during drying, which is the key to precipitation quality preservation. Enzyme is a special protein. Corn is a grain and a living organism. All its biochemical processes are catalyzed and regulated by various enzymes. The activity of enzymes increases with the increase of temperature. However, when the temperature exceeds 55℃, the activity of enzymes begins to decrease. If the temperature continues to rise, the enzyme may denature and its activity will be destroyed.
Impact on fat
The fat in corn does not change significantly below 50℃. If the temperature is above 60℃, the fat will become rancid due to oxidation and the fat will decompose into fatty acids. Higher drying temperature will increase the fatty acid value of corn. Corn with high fatty acid value is not easy to store, and the taste becomes sour and the quality is reduced.
Impact on cellulose
Cellulose is an important polysaccharide in corn. The fiber content of dried corn decreases with the increase of drying degree, because too high temperature will produce scorch, the fiber content will decrease, and some of the fiber will be converted into furfural. Therefore, in the alcohol industry, the control of burnt kernels is strict, because the furfural produced in burnt kernels will reduce the oxidation value of alcohol products and affect the quality of alcohol.
Impact on vitamins
The vitamins in corn include A, B, E, D and C. When the temperature exceeds 50℃, vitamins E, B and C will change. Therefore, the drying temperature should be controlled during drying. If the temperature is too high, the vitamins will be destroyed by high temperature.
Impact on appearance quality
Practice has shown that the general grain temperature below 50℃ has little effect on the color and taste of corn; when the grain temperature is between 50 and 60℃, the color of corn becomes lighter and the original fragrance is greatly reduced; when the grain temperature is above 60℃, the corn becomes gray and loses its original sweetness. If the drying temperature is not well controlled during the drying process, a large number of burnt grains will be produced, or the moisture content of some grains will be too low, which will cause the corn grains to break during transportation or delivery, increase the number of imperfect grains, and be intolerant to storage, affecting the quality of corn.
Post time: Jan-02-2025