Controlling the humidity of the cereal is the most important process in maintaining the quality of non-perishable preserved foods, such as cereals and legumes. In fact, improper food storage leads to the loss of quality and nutrients and, consequently, to the loss of value and the unusability of the product.
The cereal, in fact, needs to expel the carbon dioxide present inside its core in order to be not suffocated: in this phase of "breathing" it emits a lot of heat that must be necessarily expelled outside in order to not increase the internal temperature . When the cereal is stored without respecting the storage regulations, it favors the proliferation of fungi, molds and bacteria which, blocking the escape of heat from the cereal core, would cause it to suffocate.
The term "dry chain" describes the initial dehydration process of durable products to levels that prevent fungal growth, followed by storage in moisture-proof containers. In this article, Mecmar offers some useful information on the best processing process to minimize crop losses.
Drying as a preparation for the correct storage of cereals
To treat cereals safely for consumption and storage, it is necessary to use agricultural machinery specifically designed to remove moisture, which is harmful for storage. Grain dryers use hot air to obtain perfectly dried grains, avoiding the risk of decomposition and the onset of mold or aflatoxins.
The drying process reduces losses due to time, wildlife or storage, and extends the available harvest period. Thanks to this process, the quality of the cereal and acceptability on the market are improved and therefore its value increases.
After harvesting, the humidity of cereals, and corn, can vary from a minimum of 17-18% to a maximum of 33-35% depending on the climatic conditions and the stage of ripeness of the product. Excess water must be quickly removed by bringing the cereal to the safety limit set at 13-15%. This value allows to minimize quantitative and qualitative losses, and to make the product safe during the storage period.
After the drying of the cereals, the cooling phase is a fundamental moment in the manufacturing process for the product's shelf life.
The methods and execution times are closely related to the temperatures used for drying. The cooling methods differ due to on the type of dryer: it can take place in an area of the column, or it can take place at the end of drying using the same fan previously used to blow in the hot air.
One way of cooling is to anticipate the end of the drying process when the grain has reached residual moisture values between 16 and 10% and transfer it directly to the ventilation silo. By exploiting the effect of residual heat, the migration of water out of the cereal is favored and the completion of drying by the ventilation air is completed.
One method that significantly improves the quality of the stored product is the refrigeration obtained by ventilating with cooled and dehumidified air from refrigeration machines. As the temperature drops, the duration and effectiveness of the treatment increase over time. By keeping the cereal at a low temperature, it is possible to store it with a higher humidity level, increasing the quantity of saleable product. After the cooling phase, the product already stored must be subjected to further checks: at least one analysis must be performed during the entire storage period.
Healthy, clean and dry cereals can be stored for up to three years if proper drying treatment has taken place that don’t promote self-heating. To allow such durability of the dried product, it is also necessary that the warehouse prepared for storage is adequately ventilated and with an air temperature lower than that of the cereal so as not to allow the passage of water vapor between the air and the cereal.
Thanks to drying, no additional equipment is required to maintain product quality, as long as the integrity of the storage container is preserved. The drying process allows rapid and optimal removal of moisture from any type of cereal and legume, ensuring maximum safety and minimizing crop losses.
Thanks to the entire process, the beans are dried without their quality being compromised, ensuring long-term and risk-free storage thanks to the removal of excess moisture.
The mobile dryers can be easily combined with shed or silo storage systems and allow a greater level of flexibility to continuous cycle dryers which require a thoughtful preparation of the system that will be as it is for many years to follow. Here is an example of how Mecmar dryers can be connected to one or more silos:
Mecmar has decades of experience in the design of industrial dryers for cereals. If you want to learn more about the vast range of solutions for drying cereal, do not hesitate to contact us, the Mecmar team will respond to your every need.