When storing potatoes, ensuring proper air movement is essential to maintain the quality of the potatoes for the maximum duration. Managing moisture levels and temperature from the moment the harvest is placed into storage is crucial. By doing so, the supply of potatoes can be extended for a longer period between harvests. In this article, we will delve deeper into the significance of circulation and ventilation in potato storage facilities. We will also explore the use of different types of fans and their roles in maintaining optimal storage conditions. This comprehensive understanding will help in preserving the quality of potatoes for extended periods.
The preservation process holds two core challenges:
- Preventing weight loss
- Preventing sprouting
Preventing weight loss in potatoes
Potatoes lose a significant amount of moisture through a process known as 'respiration.' During respiration, potatoes absorb oxygen, leading to the conversion of sugars into water and carbon dioxide (CO2). This process also releases heat. By maintaining the correct temperature during storage, the rate of respiration can be slowed down, thereby reducing moisture loss and preserving the quality of the potatoes for a longer period. Proper temperature control is essential to slowing down this natural process, which in turn helps to extend the shelf life and maintain the overall quality of the stored potatoes.
“Potato respiration is at its lowest between 4 and 8°C. Their respiration intensity increases sharply starting from 15°C and at temperatures below 4°C. Particularly in well-insulated storages (low oxygen), increased respiration can lead to CO2 accumulation and internal black discoloration. An excessively high CO2 content leads to sprouting..."
Source: Potato storage: construction and storage process
The importance of ventilation as a sprout inhibitor
In addition to limiting moisture loss, it is crucial to keep the potatoes in dormancy for as long as possible. The rate at which potatoes begin to sprout is influenced by several factors, including the temperature during the growing season, the conditions in the storage facility, and the specific type of potato. To address these factors, modern potato storages employ various complex circulation and ventilation technologies tailored to the needs of the specific crop. These advanced technologies help in maintaining the ideal storage environment, ensuring that the potatoes remain in good condition by managing temperature, humidity, and airflow. By utilizing these sophisticated systems, the dormancy period can be extended, further preserving the quality and prolonging the shelf life of the potatoes.
The use of high pressure fans in potato storages
The ventilation in potato storages is based on 100 m3 air per m3 of potatoes (edepot.wur). Because the potatoes are stored in bulk or in boxes, air ducts as shown in Figure 1 are used. These ducts are used to dry the potatoes at the bottom of the pile as well. Since a considerable amount of air is being moved through a small duct and in between the potatoes, the pressure due to resistance can rise to 150 Pascal. Fans with a higher pressure range are used for this purpose. In the example below, the potato fans are connected to the air duct as well as the space above the potatoes, with a chimney. This way, air can circulate through the storage.
Figure 1
Source: edepot.wur
The use of circulation fans in potato storages
Additionally, circulation fans are used to increase the generated air speed in the top of the storage. By mounting these fans to the ceiling along the length of the storage, air circulation is improved and, as a result, the drying and cooling process.
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Cleaning potato storages of Chlorpropham (CIPC)
In addition to technical climate control means, predominantly chemical sprout inhibitors are used. Chlorpropham, a powder that is sprinkled over the potatoes, used to be a popular example of this type of product. This product was recently banned in Europe however. Although a transition period is in place, in practice this means that in 2021, the legal quantity will go from 10 to 0.4 milligrams CIPC per kilogram of potatoes, after which this will be further reduced. (BO arable farming *2) With persistent CIPC residues in storages where the agent was previously used, according to the organization this often means a thorough cleaning and making use of temporary alternative storage. These measures will prevent contamination of new harvests.
(Mobile) circulation fans
Without Chlorpropham and the usual ventilation system, growers are faced with a challenge. To provide alternative storage with as much air movement as possible, the use of mobile and horizontal circulation fans may offer growers a temporary solution. Thanks to the relatively simple installation, drying is still possible regardless of the local situation.
If you are looking for an emergency solution for your drying or cooling process, take a look at our circulation fans or talk to one of our specialists. We'll be happy to help.
