Grower himself determines yield of storage

The yield of potato storage is determined by the costs for energy and sprout inhibition and the (unnecessary) storage losses. This is largely in the hands of the grower.

In this article a number of tips to maximize the storage yield of potatoes for long storage.

Drying and wound healing at the right temperature
The harvesting conditions and the possible presence of hollow or rotten tubers determine how intensively drying must be done in the first weeks after storage. This storage phase has a major influence on the final storage result. The aim should be to prevent fungi and bacteria from affecting healthy potatoes. Wound healing must take place at the same time. With good wound healing, the moisture loss during storage will be lower. The moisture loss due to damage to the skin is up to 300 times higher than with a well-ripened (or wounded) skin!

Wound healing is faster at a higher temperature and RH (>80%) and a low CO₂-degree. So when product arrives cold (<12 °C), it is recommended to heat the product with a stove to ± 15 °C. Another advantage of this is that, at higher outside temperatures, it is also possible to ventilate with outside air in order to dry out a little more, if desired.

Short but powerful cooling (not too cold)
Short-term cooling with outside air with a larger temperature difference (up to 3 °C for potatoes) ensures that ventilation is shorter with outside air and cooling takes place more quickly. This prevents unnecessary weight loss through external ventilation.

The above example shows that the outside air at 12 °C and 10 °C has approximately the same moisture difference with the potatoes. But the cooling capacity of the colder air is 8,1 - 5,8 = 2,3 kJ/kg = 40% greater! So with 40% shorter ventilation and drying out, the desired temperature is reached. However, this does not apply to batches with rot, because then it is better to work with a smaller temperature difference. Cooling then takes longer, which means that the drying process takes longer, so that the moisture from leaking tubers is better drained off.

Storage temperature
Rapid cooling to the optimum storage temperature results in a slower respiration rate. Less starch is then converted into sugars, which are used for maintenance respiration of the tubers. This also contributes to limiting weight loss. However, the contribution of this to the total is smaller than due to moisture loss due to incorrect ventilation. What is especially important is that the storage temperature is constant and adapted to the variety. The more constant the storage temperature, the less germicidal the potatoes are. Because temperature changes and condensation moisture stimulate germination.

This also includes paying close attention to settings that determine when storage starts with external ventilation (outside temperature in relation to product temperature) when outside temperatures fluctuate. By reducing that setting, cooling starts just a little earlier, so that temperature fluctuations in the product remain limited. The Vision Control can also do this automatically with the Weather in Control module.

Mechanical cooling
With a mechanical cooling, keeping the storage temperature constant is no problem. It often results in a high energy bill. Ventilating and cooling with outside air always costs less energy than when the compressor has to work. The advantage of mechanical cooling is a lower weight loss. With long storage until the summer, this can amount to up to 3% less weight loss. In net terms, therefore, more salable product remains.

You can limit the energy consumption of the cooling by setting the climate computer in such a way that it does not cool too much at the product temperature during the day. The installation can then cool more efficiently during the night. That saves energy. If energy is generated by solar panels on the company, the situation can also be the other way around, so that cooling during the day does yield savings.

Germ inhibition
The new sprout inhibitors for ware potatoes are a considerable cost item in long-term storage. The effect of administration should therefore be as high as possible. The application of the new generation of germ inhibitors requires that the product, the room and the cooling installation are dry (no condensation water) and that the correct air circulation (reduced speed) is applied. The product is then distributed evenly. Keep the room closed for one to two days after the treatment and occasionally ventilate briefly internally. Turn off the cooling for a while to prevent condensation from forming, which can cause the agent to precipitate and possibly damage materials used in storage.

Pay close attention to the progress of the germination. In the case of agents that burn off germs, this determines the time of the next treatment. A tight and flat storage temperature without condensation is the basis for this. Sufficient (and not too much) CO₂ refresh based on CO . readings₂meter ensures that baking quality is maintained and extends the long-term effect of the sprout inhibitor. This year, more than ever, successful application of germ inhibitors is the basis for a high storage yield.

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