Storage is a critical step in the potato production cycle that helps farmers meet the demand for their crops throughout the year. If it is not done well, it can have economic consequences.
Around 10 million tonnes of Russian potatoes are stored every year, and the crop can spend just as long in storage as it does in the ground.
If done correctly, the potatoes arrive from storage in perfect condition. However, if stored poorly, tubers can spoil and even rot in storage, and losses increase quickly.
To help remedy the situation, we have prepared comprehensive recommendations for how to extend the shelf life of potatoes.
Ventilation is a fundamental aspect of potato storage, helping to dry and cool the crop when it is placed in storage and to remove heat generated by breathing throughout the required storage period.
In a well-designed potato storage facility, airflow will be uniform, ensuring that there are no "hot spots" that can lead to condensation and increased risk of bacterial or fungal diseases of tubers and sprouting.
Good airflow is easiest to achieve with bulk storage. In container storage, air distribution is more difficult: a poorly functioning system distributes air unevenly, properly ventilating only the "tops", while the bottom layer of the containers remains untouched.
2. Air leakage if the storage room is not airtight.
Air leakage is one of the main problems in commercial warehouses which can reduce the primary objective of potato storage - the creation of a controlled environment which maintains the tubers in optimum condition. This leads to condensation and germination.
Combating these problems by additional ventilation or cooling, without eliminating the source of the problem, results in higher operating costs and increased tuber weight loss. It is best to perform an air tightness test on the entire building.
As far back as the 1950s, it was known through experiments that living tubers use sugars to breathe, consume oxygen, and emit carbon dioxide and heat.
New research found that the intensity of respiration stabilized, especially at lower temperatures. After the initial temperature drop, cultures stored for long periods of time may not need as much ventilation as previously thought. This can lead to potential efficiencies and energy savings.
4. Disease identification
One of the key factors is to correctly identify the wide range of diseases and storage defects found in potatoes.
Two skin defects that are often confused are silver scab and potato anthracnose, which both affect the marketable appearance of potatoes.
Anthracnose is an infection that can only be picked up in the field and not spread in the store, while silver scab can be seed-borne, soil-borne or spread in the store, so proper identification will help target management.
For silver scab, warm and humid conditions promote spread in storage, so maintaining cool temperatures and minimizing condensation reduce the risk of exacerbating the problem.
Anthracnose should be controlled in the field with longer crop rotations, clean seed, weed control, and fungicides. The susceptibility of varieties also varies. Although anthracnose does not spread in storage, it can worsen on the surface of affected tubers. A rapid reduction in storage temperature will help slow the development of the disease.
5. Temperature and condensation control
Achieving and maintaining the correct storage temperature is critical to preventing a number of problems (especially condensation in storage). Condensation for as little as one hour can lead to disease development or the beginning of rotting. The key parameter here is temperature fluctuation in the storage room.
Condensation forms when warm, moist air comes in contact with cold surfaces. But condensation can also form on the crop itself if the air around the potatoes is warmer than the potatoes itself, or if the surface temperature of the potatoes is lower than the dew point temperature of the air.
To avoid this, growers must precisely control the temperature in the storage room - ideally it should vary by +/- 1C. It is very important to modernize old storage facilities to achieve this goal. Better yet, consider investing in new, modern storage facilities with automatic control systems.
Potatoes can be bruised or otherwise physically damaged during harvesting and processing, and these "wounds" must be healed to minimize bacteria entering the tubers and causing storage problems.
Potatoes have a natural defense mechanism in which suberin is formed between damaged cells, creating a barrier to infection. The rate at which wounds heal depends on temperature.
Studies have shown that a process called "dry healing" - where ambient air is used directly as crops enter storage for simultaneous drying, cooling, and curing - significantly slows tuber disease development.
7. Carbon dioxide management.
Breathing the tubers in the storage room produces carbon dioxide, which accumulates in the atmosphere. If this is allowed to happen without blowing fresh air into the storehouse it can disturb the optimum color of the potatoes because the sugar level in the stored tubers rises.
Modern automated systems use sensors to monitor the level and expel the gas from the storage room if a threshold value is exceeded.
8. Health and Safety
A potato storage facility is not the safest place to be. Managers are urged to conduct a risk assessment and take steps to reduce risks.
Storage facilities should be ventilated regularly with fresh air to reduce carbon dioxide levels to protect not only the crop, but also the staff.
You can read about storage techniques here.
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